MEP-803A Repair Assistance

Lucky Bud

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Get a hose and a bucket. Put diesel in the bucket. Unhook the input side of the E2, (primary electric fuel pump. I would even take the E2 off, so I could look into the E2 opening, to loo for trash. Is there a tiny filter screwed into the E2? If so, I would replace it if there is. Its not an expensive part. But the will remove it from the equation. Then remount the E2. Hook the hose up to the inlet fitting. Then start the set. How long will it run?
Got it.
sounds like we’re testing the primary.
I have another identical unit sitting next to it that runs flawlessly.
does it make sense to swap the primaries out or switch with the auxiliary ?
am looking for a replacement for the small filter.
took it off awhile back and it looked fine and had no resistance when I blew thru it.
 

Ray70

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The small filter is an Airtex G-17 strainer. Think last time I bought was from Rock Auto.com, I also bought from Summit racing before.
 

Ray70

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I have seen my fair share of primary pumps ( both the square and round ) go bad.
Perfect at full load 1 day, then dies after a short time the next day.
Failure mode is typically that the machine will start and run but will bog down and die over time.
Run time seems directly related to the amount of load on the motor. Light load will run longer than a heavy load. ( eventually you run out of fuel )
Pump sounds fine, but in fact has lost pressure.
The DN2M and DN4M will not run with just flow, such as gravity feed. It needs about 5 psi to the metering pumps just to stay running with no load.
Simply disconnecting the line and looking for fuel flow may not tell the whole story, you can try splicing in a low pressure gage and see if you loose pressure when the gen starts to die off, if G-17 looks good. ( its a strainer not filter so you can back flush with cleaner or air if it seems clogged.)
 

Lucky Bud

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Kerens Texas
The small filter is an Airtex G-17 strainer. Think last time I bought was from Rock Auto.com, I also bought from Summit racing before.
Went ahead and pulled a pump and filter known to be be good and installed on the unit.
ran fairly steady for 19 min and began to droop.
drooping continued for another 10 min. Until it was swinging like a pendulum between 56 and 64 HZ
seems like it takes it longer each time to fail. It started to fail in the beginning at 5 min and graduated to 10 to 15 and now to 19 minuet’s. Drooping is not as severe as in the beginning.
I’ll time it again tomorrow.
have included a picture of Woody Williams signing my 1966 Mutt
we we’re in country at the same time in 1968.
 

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Lucky Bud

Member
36
12
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Location
Kerens Texas
I have seen my fair share of primary pumps ( both the square and round ) go bad.
Perfect at full load 1 day, then dies after a short time the next day.
Failure mode is typically that the machine will start and run but will bog down and die over time.
Run time seems directly related to the amount of load on the motor. Light load will run longer than a heavy load. ( eventually you run out of fuel )
Pump sounds fine, but in fact has lost pressure.
The DN2M and DN4M will not run with just flow, such as gravity feed. It needs about 5 psi to the metering pumps just to stay running with no load.
Simply disconnecting the line and looking for fuel flow may not tell the whole story, you can try splicing in a low pressure gage and see if you loose pressure when the gen starts to die off, if G-17 looks good. ( its a strainer not filter so you can back flush with cleaner or air if it seems clogged.)
Thanks
went ahead and replaced with one known to be good with the darn same results.
still scratching.
 

Ray70

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Are you able to throw around 50% load on it and see if it dies quicker or slower?
I still recommend testing fuel pressure when it acts up.
Any smoke when it starts to act up?
Another test could be to leave radiator cap loose and run it. I'm curious if you have a head gasket starting to leak into a cylinder.
90% of the time higher cylinder pressure would leak into lower pressure radiator, but in some instances you can get coolant into the cylinders on intake stroke.
Make sure coolant isn't low and oil isn't overfull ( or milky )
 

Lucky Bud

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Kerens Texas
Are you able to throw around 50% load on it and see if it dies quicker or slower?
I still recommend testing fuel pressure when it acts up.
Any smoke when it starts to act up?
Another test could be to leave radiator cap loose and run it. I'm curious if you have a head gasket starting to leak into a cylinder.
90% of the time higher cylinder pressure would leak into lower pressure radiator, but in some instances you can get coolant into the cylinders on intake stroke.
Make sure coolant isn't low and oil isn't overfull ( or milky )
I’m on it thanks
 

Guyfang

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Like Ray, I think its a fuel pressure problem. So, we can eliminate the E2 and filter/strainer, but still, you are feeding from the tank. That's why I said to feed from a bucket. That way you would have completely separated the fuel tank AND E2. Have seen problems like this, and they were often in the tank or E2. You eliminated the E2 and filter, but are still feeding from the tank. And until you can rule that out, its still a possibility.
 

Lucky Bud

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Kerens Texas
Like Ray, I think its a fuel pressure problem. So, we can eliminate the E2 and filter/strainer, but still, you are feeding from the tank. That's why I said to feed from a bucket. That way you would have completely separated the fuel tank AND E2. Have seen problems like this, and they were often in the tank or E2. You eliminated the E2 and filter, but are still feeding from the tank. And until you can rule that out, its still a possibility.
Got it.
will do that tomorrow.
thanks
 

Dieselmeister

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You can also pull off the fuel return line at the tank and point it into the tank fill opening (you might have to add a short piece of hose). See if fuel comes out, but stops flowing when the machine starts to droop. Then you will know if its a fuel delivery problem. Any chance the pump is sucking air when things warm up?

Looking at the time to droop, it almost looks like the issue is temperature related. Any chance you are loosing compression when things heat up?
After the machine stops running, and you crank it, does it sound like you have compression, or does it just spin easy?
 

Lucky Bud

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Location
Kerens Texas
You can also pull off the fuel return line at the tank and point it into the tank fill opening (you might have to add a short piece of hose). See if fuel comes out, but stops flowing when the machine starts to droop. Then you will know if its a fuel delivery problem. Any chance the pump is sucking air when things warm up?

Looking at the time to droop, it almost looks like the issue is temperature related. Any chance you are loosing compression when things heat up?
After the machine stops running, and you crank it, does it sound like you have compression, or does it just spin easy?
It’s cold out, but I managed to pull the pump and give it a physical and reinstall pumping out of a diesel can.
seems like it made it past 20 minuets but it still failed and began drooping after warm up.
it’s always gotten better each time I tried something and timed it. Put it back together and fired it up the next day.
ambient temp was about 45f. Ran well for 30 minuets and hope was beginning to build. Ran it for a solid hour with no failures.
ran it again today withe the temp at 60 degrees and had no failures for an hour. Temp was stable at 180 and oil held at 42 lbs.
it my have decided to run without giving up its problem. Thinking a sender or an injector pump.
thank y’all for your time.
Im sure it will haunt me again.
going to put her to work.
 

Light in the Dark

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If you can go without the machine for a few days, pull all of the metering pumps out and let them sit fully submerged in carb cleaner covered and out of the way (getting them lined back up properly in the fuel rack is not difficult... but thats why some folks say to leave 1 in, but it only takes an extra 15 seconds to get them aligned properly if you pull them out). After a few days, work them over and compress the pumps and confirm they are working properly. They are dual action... rotation of actual fuel delivery based on the position of the fuel rack, as well as the metered fuel delivered out of the top.

I've had sets experience drooping and stalling failures that have cleared up by the method above.
 

Lucky Bud

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Location
Kerens Texas
If you can go without the machine for a few days, pull all of the metering pumps out and let them sit fully submerged in carb cleaner covered and out of the way (getting them lined back up properly in the fuel rack is not difficult... but thats why some folks say to leave 1 in, but it only takes an extra 15 seconds to get them aligned properly if you pull them out). After a few days, work them over and compress the pumps and confirm they are working properly. They are dual action... rotation of actual fuel delivery based on the position of the fuel rack, as well as the metered fuel delivered out of the top.

I've had sets experience drooping and stalling failures that have cleared up by the method above.
Thanks for that.
Nice to have the help out there
 

Guyfang

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Before a gen set left my repair shop, it had to run under a full load, (No, NOT 120% load!) for 6-8 hours to be considered fixed. So when ever you THINK its fixed, you should at least run it under load, and at least 4-6 hours. You never NEED a generator, until you NEED a generator.
 

Lucky Bud

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Kerens Texas
Before a gen set left my repair shop, it had to run under a full load, (No, NOT 120% load!) for 6-8 hours to be considered fixed. So when ever you THINK its fixed, you should at least run it under load, and at least 4-6 hours. You never NEED a generator, until you NEED a generator.
I understand that.
wish I had a way to load it without moving it.
crossing my fingers flying in the fog.
 

Guyfang

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There are about a million threads on load banking and building a simple, SAFE and cheap load bank. Maybe take a look see. It truth, its must not cost a million bucks and can be safe. A trip to the local junk yard might turn up some dryer heating coils, and a few other parts that can be used to SAFELY turn it on and off.
 

Lucky Bud

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Kerens Texas
There are about a million threads on load banking and building a simple, SAFE and cheap load bank. Maybe take a look see. It truth, its must not cost a million bucks and can be safe. A trip to the local junk yard might turn up some dryer heating coils, and a few other parts that can be used to SAFELY turn it on and off.
Will do
thanks
 
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