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Hi there

My X758 has begun to stall...almost like it runs out of fuel. I searched this forum and found a thread about almost the same thing but mine is different.

I would be running about 10 to 20 minutes and then the engine would slow and either gradually stop or regain itself. If it stalled, I could just turn the key and it would start right back up again. After a while, it would stall or slow and regain after 2 or 3 minutes.

After reading the previous thread about the same thing, I took to troubleshooting fuel lines. The pick up pump pumps well, the fuel filter is clean with no sediment or water in the bulb and I even took the pick up pump apart to clean and blow out any dirt.

I think this may be electrical in nature. The reason I say so is that I notice before the engine is about to slow to a stall, or even stall, the engine oil light comes on. The oil level is fine, I checked it many times. I am wondering if there is a engine cut off attached to the oil pressure gauge? Does that make sense?
 

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Hi there

My X758 has begun to stall...almost like it runs out of fuel. I searched this forum and found a thread about almost the same thing but mine is different.

I would be running about 10 to 20 minutes and then the engine would slow and either gradually stop or regain itself. If it stalled, I could just turn the key and it would start right back up again. After a while, it would stall or slow and regain after 2 or 3 minutes.

After reading the previous thread about the same thing, I took to troubleshooting fuel lines. The pick up pump pumps well, the fuel filter is clean with no sediment or water in the bulb and I even took the pick up pump apart to clean and blow out any dirt.

I think this may be electrical in nature. The reason I say so is that I notice before the engine is about to slow to a stall, or even stall, the engine oil light comes on. The oil level is fine, I checked it many times. I am wondering if there is a engine cut off attached to the oil pressure gauge? Does that make sense?
check the grounds. The main ground, the chassis ground, etc.

Also, do you have access to a Technical Service Manual? The schematic is extremely handy. I have one for the 455 diesel, but not the newer x758........
 

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Sounds fuel related to me also.

First quick/easy/free test is to loosen the fuel cap a little bit and see if it continues to do it. Sometimes the vent in the fuel cap will get plugged - as fuel starts to be used in the tank - like Your 10-20 minutes - if the vent is blocked it will created a vacuum in the tank and not let fuel flow through the lines.
 

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How many hours on your machine?

I am sure you saw in it mentioned in the other threads you likely read, but some of the fuel lines have been known to weaken and "internally collapse". I had this happen on one of my machines and it was tricky to find. I ran a temporary supply line from the pick up to the fuel filter and discovered it that way.

Your machine doesn't have the electrical fuel pump like some of the other machines mentioned in the threads about this issue. Your machine uses the Mikuni mechanical fuel pump........which is mounted on the side of the injector pump. To be honest, we just don't see actual "Injector Pump" issues with these Yanmar's. I can't recall when one needed attention......I am referring to the actual Fuel Injector Pump assembly, the device which puts the fuel under very high pressure for injection into the cylinders. I am not referring to the "Fuel Pump", which in your machine, it attached to the injector pump.

It could be bad fuel......

Perhaps the fuel has contaminants. Was there any water in your fuel separator or anything unusual about that? I would manually turn the fuel shut off on and off several times, just to make sure there is nothing stuck in it or causing the fuel issue.

When the machine starts to "lose power", does it matter if you are on a flat surface or a hill?

Anything else to report, such as "Does it happen when running the PTO only" or does the loss of power and stalling happen regardless of whether the PTO is engaged or not?

Is the machine running warmer than usual on the temp gauge?

What makes you think it could be related to the Oil Pressure system or switch? Have you noticed some other issue which brings that to mind?

Have you changed the fuel filter? If so, do you have it installed tightly in the fuel separator (pressed up on the center mounting post in the container)?

Any fuel leaks or other fluid leaks you have noticed lately?

Any idea how ld the fuel is? Did you get it at the same place you normally purchase your fuel? DO you run any fuel treatments in your fuel?

Does the battery seem fully charged and it easily restarts the machine when needed? If you have the headlights on when you restart the machine, do the headlights dim significantly or almost "go out" when restarting the machine?
 

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Fuel Solenoid Switch Operation / Testing
You could also have a situation where the fuel shut off solenoid is not holding in the open position when the tractor is running, which would cause the shut down. But, generally, these tend to fail and NOT OPEN, failing to permit the tractor to start. I personally haven't seen one which fails to hold in the "Open Position" when the tractor is running, causing the tractor to fail, but it is mentioned in the Technical Service manual as something to check.

The normal findings for the shut off solenoid should be it maintaining battery voltage with the tractor running.


Oil Pressure Sensor Switch Operation / Testing
There is also a testing procedure for testing the Oil Pressure Sensor Switch.....

1. Set ohm meter for 1x ohms scale
2. Remove the wire from the center of the oil pressure sensor switch
3. Connect black lead from ohm meter to engine block
4. Connect red lead to terminal on the oil pressure switch
5. Read the Meter....Note reading
6. Start and run engine, Note reading

With the engine NOT running, there should be continuity to ground

With the engine running, NO continuity to ground.

If the switch does not have continuity to ground when the engine is NOT running, replace the switch.

If the switch does have continuity to ground when the engine is running, you need to manually check the engine oil pressure to make sure it is within the specifications. If the oil pressure is to specifications, then replace the switch. If the oil pressure is not to specifications, that issue must be resolved.
 

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I know I'm comparing apples to oranges. But I've mentioned the issues of Harley's X738 since it was new 2 yrs ago. \

At first the engine seemed to die while going down a hill and then trying to backup. Then it would do it on level , going up a hill, full of gasoline or on a 1/4 tank.
The mower never shuts off when this happens and engine has never completely stopped running.

After the dealer had machine for close to 5-6 weeks. maybe more the tech said it finally acted up while he was mowing. The shop finally claimed they found a loose ground wire. They never showed me which one of the grounds was loose.

So just wondering if same issue with diesel and gasoline engines. :dunno:

Knock on wood so over the past 6-8 mowings this season it has only happened once , last season it happened about every other week. Some times 2-4 times while mowing.
 

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Discussion Starter #7
How many hours on your machine?

I am sure you saw in it mentioned in the other threads you likely read, but some of the fuel lines have been known to weaken and "internally collapse". I had this happen on one of my machines and it was tricky to find. I ran a temporary supply line from the pick up to the fuel filter and discovered it that way.

Your machine doesn't have the electrical fuel pump like some of the other machines mentioned in the threads about this issue. Your machine uses the Mikuni mechanical fuel pump........which is mounted on the side of the injector pump. To be honest, we just don't see actual "Injector Pump" issues with these Yanmar's. I can't recall when one needed attention......I am referring to the actual Fuel Injector Pump assembly, the device which puts the fuel under very high pressure for injection into the cylinders. I am not referring to the "Fuel Pump", which in your machine, it attached to the injector pump.

It could be bad fuel......

Perhaps the fuel has contaminants. Was there any water in your fuel separator or anything unusual about that? I would manually turn the fuel shut off on and off several times, just to make sure there is nothing stuck in it or causing the fuel issue.

When the machine starts to "lose power", does it matter if you are on a flat surface or a hill?

Anything else to report, such as "Does it happen when running the PTO only" or does the loss of power and stalling happen regardless of whether the PTO is engaged or not?

Is the machine running warmer than usual on the temp gauge?

What makes you think it could be related to the Oil Pressure system or switch? Have you noticed some other issue which brings that to mind?

Have you changed the fuel filter? If so, do you have it installed tightly in the fuel separator (pressed up on the center mounting post in the container)?

Any fuel leaks or other fluid leaks you have noticed lately?

Any idea how ld the fuel is? Did you get it at the same place you normally purchase your fuel? DO you run any fuel treatments in your fuel?

Does the battery seem fully charged and it easily restarts the machine when needed? If you have the headlights on when you restart the machine, do the headlights dim significantly or almost "go out" when restarting the machine?
Thanks for the response SulleyBear, let me try to fill you in with info:

The tractor has about 150 hours on it and it ran fine all winter plowing snow and into the first 2 or 3 lawn cuts this spring. I put a new filter in last spring and recently had the filter out to check for sediment and water in the bowl. No evidence of water (i.e. no white-ish colour) but a wee bit of sediment, which I cleaned out. I did take the pump off and clean it out. I blew through the inlet and outlet to ensure a clear way and there were no blockages.

It may be bad fuel. I did get my gerry cans filled at a different service station last time around. I may have to resort to draining the fuel tank and trying different fuel. I don't use treatments and the fuel was purchased the same day I started having trouble.

The stalling happens while the PTO is engaged and throttle is full. It can idle forever...I had it idling for ten minutes and no issues. It doesn't favour hills or flats when stalling. Engine temp is warm, but not over hot. The oil light illuminates at full throttle just before its about to cut out. That's why I thought it may be that.

I guess I can check the lines but that means getting at the tank, which I really dont know how to do.

Cheers
 

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Discussion Starter #8
Fuel Solenoid Switch Operation / Testing
You could also have a situation where the fuel shut off solenoid is not holding in the open position when the tractor is running, which would cause the shut down. But, generally, these tend to fail and NOT OPEN, failing to permit the tractor to start. I personally haven't seen one which fails to hold in the "Open Position" when the tractor is running, causing the tractor to fail, but it is mentioned in the Technical Service manual as something to check.

The normal findings for the shut off solenoid should be it maintaining battery voltage with the tractor running.


Oil Pressure Sensor Switch Operation / Testing
There is also a testing procedure for testing the Oil Pressure Sensor Switch.....

1. Set ohm meter for 1x ohms scale
2. Remove the wire from the center of the oil pressure sensor switch
3. Connect black lead from ohm meter to engine block
4. Connect red lead to terminal on the oil pressure switch
5. Read the Meter....Note reading
6. Start and run engine, Note reading

With the engine NOT running, there should be continuity to ground

With the engine running, NO continuity to ground.

If the switch does not have continuity to ground when the engine is NOT running, replace the switch.

If the switch does have continuity to ground when the engine is running, you need to manually check the engine oil pressure to make sure it is within the specifications. If the oil pressure is to specifications, then replace the switch. If the oil pressure is not to specifications, that issue must be resolved.
Thanks SulleyBear, will give that a try.
 

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Sounds fuel related to me also.

First quick/easy/free test is to loosen the fuel cap a little bit and see if it continues to do it. Sometimes the vent in the fuel cap will get plugged - as fuel starts to be used in the tank - like Your 10-20 minutes - if the vent is blocked it will created a vacuum in the tank and not let fuel flow through the lines.
I tried that too. After a stall, I loosened the fuel cap to determine if I could hear any hissing from a vacuum. No such sound. Thanks for the suggestion.
 

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Thanks for the response SulleyBear, let me try to fill you in with info:

The tractor has about 150 hours on it and it ran fine all winter plowing snow and into the first 2 or 3 lawn cuts this spring. I put a new filter in last spring and recently had the filter out to check for sediment and water in the bowl. No evidence of water (i.e. no white-ish colour) but a wee bit of sediment, which I cleaned out. I did take the pump off and clean it out. I blew through the inlet and outlet to ensure a clear way and there were no blockages.

It may be bad fuel. I did get my gerry cans filled at a different service station last time around. I may have to resort to draining the fuel tank and trying different fuel. I don't use treatments and the fuel was purchased the same day I started having trouble.

The stalling happens while the PTO is engaged and throttle is full. It can idle forever...I had it idling for ten minutes and no issues. It doesn't favour hills or flats when stalling. Engine temp is warm, but not over hot. The oil light illuminates at full throttle just before its about to cut out. That's why I thought it may be that.

I guess I can check the lines but that means getting at the tank, which I really dont know how to do.

Cheers
Definitely check the oil switch / sensor as I outlined above. If the switch is defective, it very well could be your issue. If the switch is NOT defective, you certainly want to know why the oil pressure light is illuminating at full throttle. You don't want to risk damaging the engine.

I can honestly say I can't recall when one of these little Yanmar's had a oil pump / oil pressure issue, but such things can happen if the oil filter collapsed internally, is somehow plugged or the oil filter bypass isn't functioning correctly.

You want to find out if the Oil Pressure Switch / Sensor is defective (which I bet it is, or the wire is simply loose, check that first......) because if your machine is in fact having oil pressure problems, you certainly want to know that and deal with it.

Also, when was the last time the tractor had the engine oil changed? Was a John Deere oil filter used? If it's close to time for an oil change, you may want to change the oil and filter as the filter could be a factor in causing the oil light to come on......I would imagine you checked the engine oil level when you noticed the light on..........

I doubt very much your tractor has a fuel line issue, so don't bother with trying to get to the tank at this point.

I recently got a bad tank of gas in my SUV from a station I have never been too before. I was able to add treatment to the fuel and enhance the octane as well as disperse the moisture from the gas and it finally is "tolerable" but I didn't want to have to drain 25 gallons of gas out of the SUV tank.

I would also treat the fuel in the tank with some good fuel treatment, such as Howe's or Lucas, etc. DO NOT ADD THE "Emergency 911" product in the red bottles as it is full of alcohol to dry out the moisture in diesel fuel and alcohol is very abrasive and potentially destructive to the actual injector pump. I would add double the suggested amount of either "Howe's or Lucas" fuel treatment to the fuel in the tractor as excessive use of the Howe's or Lucas treatment won't cause any harm, other than a tiny dent to your pocketbook...:laugh:

I would bet its either a bad oil pressure sensor / switch,
the wire is loose to the sensor or you have some bad fuel..........

As I mentioned in my first post and also ETCallhome mentioned it, a bad ground can also cause the stalling. These diesels vibrate and as a result, they tend to loosen bolts, hardware and connections which can cause such issues. But I would start with the Oil Pressure Switch / Sensor since you have noticed the light come on right before it quits.

If necessary, you can begin to check the grounds systematically.......If you don't have a decent Ohm Meter, I encourage you to get a quality one. They are handy to have and critical to diagnose many things on these machines.

And of course, if your machine is still under warranty since it has only 150 hours on it, make sure to involve the dealership service department in resolving your issue.

You can also get the Technical Service Manual for your machine in either CD Rom or Book form. I highly suggest you get one of these as they are very valuable as a resource. It has all of the wiring schematics and helps you save a ton of time by walking you through steps to diagnose and it provides identity of the wires by color and number code. These manuals help us understand our machines much better and make working on them much easier.

Please make sure to post whatever you end up finding so that this thread can be helpful to others in the future who might experience the same issues you are now dealing with. Plus, its nice to know what the actual problem turned out to be.


Thanks.............
 

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I know I'm comparing apples to oranges. But I've mentioned the issues of Harley's X738 since it was new 2 yrs ago. \

At first the engine seemed to die while going down a hill and then trying to backup. Then it would do it on level , going up a hill, full of gasoline or on a 1/4 tank.
The mower never shuts off when this happens and engine has never completely stopped running.

After the dealer had machine for close to 5-6 weeks. maybe more the tech said it finally acted up while he was mowing. The shop finally claimed they found a loose ground wire. They never showed me which one of the grounds was loose.

So just wondering if same issue with diesel and gasoline engines. :dunno:

Knock on wood so over the past 6-8 mowings this season it has only happened once , last season it happened about every other week. Some times 2-4 times while mowing.

Gene, the bad ground would affect either the gas or diesel models. You are right about mentioning it. I also think it could be related to the oil pressure switch / sensor based upon the OP's comments. But the grounds can certainly cause the problem and it can be a real tough one to track down as it can be somewhat "Intermittent" because of the way 'faulty" electrical connections often function.......

Gene, I hope you and your family have a wonderful weekend and Memorial Day holiday........:good2:
 

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Your problem surely sounds like lack of fuel. Slowly loosing power under load suggests loss of fuel. The oil pressure light coming on is being caused by the engine RPM slowing down due to the fuel problem. The lower RPM will sometimes cause low oil pressure, or at least lower oil pressure than the oil pressure switch is set to close at.

Possible issues.

Are you sure the valve at the top of the fuel filter is all the way open?

Is the fuel filter housing tight?

Is the seal that seals the fuel filter housing, in place correctly?

Is the fuel filter installed correctly?
 

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Your problem surely sounds like lack of fuel. Slowly loosing power under load suggests loss of fuel. The oil pressure light coming on is being caused by the engine RPM slowing down due to the fuel problem. The lower RPM will sometimes cause low oil pressure, or at least lower oil pressure than the oil pressure switch is set to close at.

Possible issues.

Are you sure the valve at the top of the fuel filter is all the way open?

Is the fuel filter housing tight?

Is the seal that seals the fuel filter housing, in place correctly?

Is the fuel filter installed correctly?
These are very good places to start.

We had a member here recently who went way deep into diagnosing a similar issue which turned out to be the fuel valve was never turned back on after changing the filter.

Do all simple things first! Also try to back track - what was the last thing you did to the tractor before this all started?
 

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These are very good places to start.

We had a member here recently who went way deep into diagnosing a similar issue which turned out to be the fuel valve was never turned back on after changing the filter.

Do all simple things first! Also try to back track - what was the last thing you did to the tractor before this all started?
Exactly. :good2:Don't look for needles in the haystack until you first verify the haystack.
 

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Do you happen to have one of those little inline plastic filters? I put a brand new one on my mower a couple weeks ago. For some reason, it wouldn't let fuel through into the carb. The engine would run great for a half hour or so and then the filter would stop the flow... I put in a screen type filter and bam, no more issues, and no more restricted flow.


 

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Thanks SulleyBear, you are a fountain of knowledge.

For now, my stalling problem is fixed. Here's what I did:

I first took apart the pickup pump, cleaned it with carb cleaner, put it back together and ran the engine. I mowed a round and a half of my lawn and it quit again. I checked the ground points...all tight.

I then went after the fuel tank. I remember someone saying that the pick-up line in the tank can get gunky. So, I grabbed my wrenches and went to figure out how to get at the tank. Turns out it's really kind of easy. Remove the seat and then remove four bolts where the back fender meet the foot pads in from of the rear wheels and a nut on the handle on the left side. The rear fender lifted off after I removed the fuel cap and undid the pig-tail for the rear lights.

I removed the main line and the return line and blew into them checking for leaks...no leaks. I then removed the grommet and pick up line from the tank and low and behold, it was caked with the black gunk from hell. I removed the pick-up line and sprayed it with carb cleaner to make sure it was spic and span. I put it all together, started the engine and proceeded to mow my lawn. No stalling.

The one thing that still is an issue is the oil light. It still comes on intermittently. I will definitely check that out.

Thanks everyone for the help. :bigthumb:
 

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Black gunk in the fuel tank can mean you have an algae problem. If this happens again in the short term it would be prudent to clean the tank and add an algaecide to your fuel for a while.

Algae grows in water which would mean you've gotten water in your fuel at some point.
 

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Thanks SulleyBear, you are a fountain of knowledge.

For now, my stalling problem is fixed. Here's what I did:

I first took apart the pickup pump, cleaned it with carb cleaner, put it back together and ran the engine. I mowed a round and a half of my lawn and it quit again. I checked the ground points...all tight.

I then went after the fuel tank. I remember someone saying that the pick-up line in the tank can get gunky. So, I grabbed my wrenches and went to figure out how to get at the tank. Turns out it's really kind of easy. Remove the seat and then remove four bolts where the back fender meet the foot pads in from of the rear wheels and a nut on the handle on the left side. The rear fender lifted off after I removed the fuel cap and undid the pig-tail for the rear lights.

I removed the main line and the return line and blew into them checking for leaks...no leaks. I then removed the grommet and pick up line from the tank and low and behold, it was caked with the black gunk from hell. I removed the pick-up line and sprayed it with carb cleaner to make sure it was spic and span. I put it all together, started the engine and proceeded to mow my lawn. No stalling.

The one thing that still is an issue is the oil light. It still comes on intermittently. I will definitely check that out.

Thanks everyone for the help. :bigthumb:
Very glad to hear you have got the tractor running. Thanks for posting the follow up to let us know what you found.

Removing the operator platform is very easy, as you said, 6 bolts and unplug some tail light wires and release the seat switch from it's plug. Lord knows I have done it enough......In fact, if you plow snow with your tractor or use it in the winter, I replaced the 6 platform bolts with stainless steel bolts and nuts so I can get it apart, even if the snow melt and road salt crud up the hardware, which will happen over time. It prevents fighting with corroded hardware down the road.......

I strongly suggest you immediately do the following;

1. Begin running fuel treatment in all fuel from now on, every jug of fuel, every month of the year. You will avoid SO MANY headaches doing this and you won't have to worry about "seasonal fuel differences"......Aggressively treat the fuel for the next several tanks to rid the tank of any possible problems, even using 3 or 4 times the recommended amount of fuel treatment. The only harm is you will spend a few extra dollars....Big deal.....Use a recognized, quality brand of treatment like Howe's or Lucas or whatever you like. Just pick one brand and stick with it.......

2. You definitely want to watch the fuel condition, both in the tank and in the fuel separator. You might want to buy a couple more fuel filters so you have them on hand until your fuel treatment cleans up the issue. Once the issue is gone, I would replace the fuel filter in the separator just so you know you have a nice, clean filter in it. The fuel filter is Deere part number MIA882276.

3. Watch the O Ring on the fuel separator when you have it open to replace the filter. If it's at all fatigued, replace it. Deere calls it "Packing" and the part number is CH10060.

4. Also, the fuel pick up line and the return line use those rubber "bushings" which the lines are pushed through to enter the tank. If either of those seem to have any wear or get damaged when you are pulling the fuel lines, don't hesitate to replace those. They are crucial for keeping the moisture and dirt out of the tank and they also protect the fuel lines against vibration and wear on the lines. They are part number M132706 and the same bushing is used on the pick up line and the return line.

5. The fuel lines are held in place on the top of the tank by those 4 "strips". They are Deere part number M167640 and you may want to have those on hand should you have to pull the lines again.

Also, just a FYI, sometimes, the fuel level sensor is position dependent. I usually mark mine before removing it as I have had where when it went back into the tank and not in the same position, the fuel gauge became unreliable. It would work sometimes and other times, not. The electrical connection was fine. When I rotated the sensor a little in the tank, it returned to it's normal reliable operation....:dunno:

Just one of those things learned from having these machines apart over the years.......

Glad you remembered the previous mention about cleaning the tank pick up. I know I have mentioned cleaning these before as I have seem them literally collapsed on the end of the fuel pick up line. The older style machines used a "brass" type pick up screen which was sort of "V" shaped on the end of the pick up line. Over time, the pick up screen would collect various crud and also weaken. Anything which obstructs fuel flow is a problem.

Your machine isn't using the screen on the end of the fuel pick up tube, from what I am seeing in the diagram. I would think having a screen would be a better idea but there is a big difference in how this fuel pump works, pulling the fuel from the tank at the Injector Pump. So, the additional restiction of a screen or pickup might be an issue for fuel delivery pressure to the injector pump.

Many of The older diesel machines prior to the x740 actually used an electrical fuel pump which was on the fuel pick up and fuel gauge sending unit, right inside the tank. So in that design, the fuel pump was a few inches from the pick up screen. In your machine, the fuel pump is a couple of feet from the pick up line in the tank.

Also, the way they have the fuel supply and return lines inserted through the "bushings" into the tank, which insulate the lines from vibration and seal them, the only way to have pick up screen on the pick up line would be to remove the fuel sending unit from the tank and reach in and insert a pick up screen on the end of the fuel supply line. It would add steps and a little more labor, so someone with a green visor and a calculator likely decided its worth just skipping the fuel pick up screen to save a buck, which I think is a bad idea.......:dunno:.

Glad you have it running again. Once it returns to running normally, it may also resolve the periodic oil pressure light coming on. Just make sure the oil level is correct and keep an eye on it. If the light was on often or continuously then I would be much more concerned. But since its intermittent and the machine is starting to run like it should (used to) let's give it a little time to see how it shakes out.

Please keep up posted if you have any more issues or what you end up doing with the oil sending unit / sensor, if anything........:bigthumb:
 
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