MEP003A wont stay running

Hey guys, New to the forum.
I just bought a Mep003a on a trailer. I got it to start, but it won't stay running. It will run anywhere from 2 to 5 mins then just act like its bogging down and die. This is what I have done so far: Drained the fuel tank, full of nasty white powder so I'm getting fuel from a clean 5 gal fuel tank. Got the governor linkage to move. It was rusty. Took all the nozzles off the injectors and cleaned them up. Found out the sec fuel pump s not working so I bypassed it. Checked the fuel pump plunger in the injection pump, it's free. Found out the air doors by the exhaust were not opening. So I removed them, should not need them as I'm down south. removed the temp sensor and left it loose away from the engine while I'm trying to find what is causing the shutdown. It's not the fuel solenoid. It stays engaged, and it doesn't seem to help any when I pull up on the governor when it wants to die. The only thing I see is I'm missing the fuel filters. Which, I'm going to install new ones. But would like to hear it stay running before I do that. I'm pulling my fuel thru a plastic gas can right now for testing. And that the electric fuel pump puts out about 4 to 6 psi before I start it afterward it drops t about 2 to 3 psi. Any Idea's ??

It sounds to me like a fuel delivery problem. The fuel pump that still works is probably overheating/failing under use, which is why you are seeing the PSI drop. I would get a new pump for this machine (especially since it sounds like you already are missing pumps...). How do the fuel lines look?

fuel lines are old but I have removed and look at every fuel line. Before I stick and a bunch of money in it just wanna make sure the engine is good. Funny thing is if i take the fuel line off the injection pump and run it in a bucket it never stops

The fact that you describe a slow roll to OFF tells me its a fuel flow issue. If it was an abrupt stop, its probably not fuel. All old fuel lines can swell sometimes too, so you may not see the problem until under use. Those Onans are pretty rugged engines... how does it sound when its running properly?

Have you inspected the return line and fittings?

Agree with LITD. I was thinking plugged fuel filters or failing fuel pump.

PM is very important. When you found crud in the tank, the first thing you should have done is clean the tank and lines, replace fuel filter, clean filter screens on the pumps and change the oil and oil filter before you ever tried to start the engine. You mentioned that the louvers weren't opening and you removed them. They don't open until the engine heats up and then only open as needed. I would re-mount the louvers. You are in the south, but it can get cool where you are. MEP003A gensets are a very good piece of equipment and very reliable. Mine gets used in power outages 10 - 15 times a year and I use it once or twice a year remotely since mine is trailer mounted as well.

Sounds like the pump is failing and not putting enough fuel to the injector pump. Don't half way do your PM, go ahead and change the filters and move forward. If your loosing 1/2 your psi I would say the pump is the problem.

That's a good machine! If you didn't hear a rod knocking in the few minutes it was running, I'd bet its good. As above, put it all back together, as the Guys above & others, are Aces on these machines. With all its parts, its as close to bullet proof as anything can be.

Ok TY to all the replies. I'm not trying to cheap out on it with the fuel system just wanna make sure it will stay running before I dump a ton of money into it. I have had just about every fuel line off of it and blew thru and looked thru each one checked the check valve and a return orfice on the injection pump. when I bought it from a private seller the fuel filters were gone and bypassed. and I ran a hose into a clean 5 gal can for testing. Whenever I buy an item that needs work I always try to make sure it works before just buying tons of parts. Been stung in the past. the doors I removed because I could not get them to open up at all. I had my temp gun read almost 200 behind the dors and they are supposed to open at 120 and be fully open at 140. tried to locate a new thermostat for them and could not. After it is running I will try with them on again, scared that it got overheated. The fuel pumps the primary one is making noise and pumping but its the one that has only 2 or 3 psi when running. the sec one is making a clicking sound but not pumping so I bypassed it. the aux one I have not unhooked yet but its running like crazy when you move the switch. I'm going to order a new pump and maybe run some rubber hose to the injection pump for testing it. Thank you for all the replies and I will keep u all updated. Ps I'm going to remove my fuel tank and try and clean it this weekend.

If you think the aux pump is good, uninstall it and reinstall as your new primary and test it. See if the condition disappears.

First you should VERIFY the p/n on those pumps. The pump p/n is stamped on the mounting flange (you probably have to remove mtg bolt and sand off any rust to read p/n on flange. It should be P/N 480517E which DOES NOT have an internal check valve nor positive shut off so they can be run in series in case one fails. I would highly recommend you read this thread pertaining to fuel pumps and their maintenance & potential resurrection:

https://www.steelsoldiers.com/showthread.php?156346-Mep-003-Fuel-Pumps

Here is a source with pump info that may help: https://www.yachtsupplydepot.com/me...te-electric-fuel-pump-480517e/prod_23449.html

Also, if you can't resurrect your pumps to output to spec. and need to buy replacement(s) do not fall for any of the Chinese Knock-Offs advertised on places like eBay, etc.

Oh, I didn't know I could take one apart. ty, I read the whole post. I did order an aftermarket 24-volt fuel pump off of amazon but I might try and take them apart and clean them. I did take the fuel tank off today drained it. Then pressure washed it out. Got everything out I could. Expect there is a baffle in it and don't know what it looks like behind the baffle. I could use acid in it to eat rust. but not really that much rust.
What type of hose do they use for the fuel lines?? Trying to locate some in town with that braiding on them and struck out. What's it called??

You aren't going to find exact fuel line material off the shelf, as you find on the 00x sets. You will need to make something up with equivalent sized modern hose and civilian fittings (they are AN-5, so you will need to source or have made a line with JIC 5/16 fittings).

Do the pumps you have match the original number that Chainbreaker called out (with inline EMI filter), or were they changed to something else before you got it?

Everyone is jumping to conclusions. You don't KNOW its a fuel problem. I would start there looking for the problem, but only after everything is clean and put back together right. Then start from step one, and go from there.

It certainly sounds like a fuel problem, but don't get fixed on that idea. You can overlook something else when that happens. Chainbreakers post #18 is VERY important. Miss-match the two fuel pumps, and that's grounds to cause the set to not work right. Take the pumps apart, and soak them in carb cleaner over night. Heck, all the fuel system parts for that matter. Get the fuel filters back on line, clean and tight.

jason74350 said:

...What type of hose do they use for the fuel lines?? Trying to locate some in town with that braiding on them and struck out. What's it called??

Click to expand...

If you have a local Hydraulic Hose shop take in an old hose to them. Most likely they will use the "Gates brand" 1/4" 1500 PSI WP braided hose with new fittings AN-5 or JIC 5/16.

took the tank off and cleaned it. going to reinstall it. got a fuel pump off amazon that is 24 volts coming. I saw the part number in here for it. going to pull the fuel pumps and check them out. I have not had time to yet. As far as a fuel problem or not. the only thing I can find is I'm losing fuel pressure when running. it goes from 6 psi to 2 psi. it is over full on oil but I do not smell fuel in the oil. going to drain off some.

Is the oil thin? Smell like oil?

Guyfang said:

Is the oil thin? Smell like oil?

Click to expand...

no it looks like it was just changed. smells just like oil. does not have any fuel smell to it. still pretty thick and clean looking.