MEP-803A issue... Won't start... HELP?!?!?!

[Jayco36REQS]

I have a MEP-803a I got from a gov auction just over 400-hrs on the meter... and I can't get this thing to start on diesel.

Some notes:
- I serviced it, all new fluids, new filters, checked the fuel tank for grime or sludge, and put new clean diesel in it.
- The fuel pump sounds noisier than other 803a's I've had but it is pumping fuel
- It starts on either
- I cracked open the fuel line on the secondary fuel filter and it is pumping fuel there.
- I pulled the rubber fuel return line off the fuel rail, and fuel squirts out in a small stream.
- I pulled the rubber fuel inlet line to the front lift-pump inlet, and fuel is coming out.
- I pulled the hard fuel line off the front lift-pump outlet, and no fuel is coming out.
- I checked the 2nd lift-pump exit, and only a dribble of fuel comes out.
- I removed the front lift-pump, it looked clean, not corroded, no wear marks, plunger moves freely.... I took the top off to inspect the inside spring, and components... again, no debris, no corrosion or wear.

Any ideas what to do from here? I'm FAR from a diesel mechanic, and have not had to go this in deep to the fuel system on one of these in over 20 units.

Questions:
1) How much fuel flow should the pump flow?
2) Best way to test the Lift-pumps?
3) Any troubleshooting tips or tricks from you guys who have vast experience with these units?

Thanks a TON!!!!

 

[DieselAddict]

Most important thing first - Don't use either on these things. It is very bad for these engines. You will crack the piston at the top ring lands.

When you say lift pumps are you talking about the 4 pumps along the side of the engine with the hard lines going up to the injectors? Those are the individual high pressure fuel pumps.

Assuming this is what you are talking about, have you checked the movement of the fuel stop arm connected to the solenoid? Does it move smoothly? Is the solenoid fully retracted when you are trying to start the engine?

You should get a pretty steady dribble of fuel at the injector if you crack the fuel line a quarter turn or so (while spinning over the engine of course). If you see any sign of air bubbles coming out the line needs to be bleed until you get good fuel out. Kinda like bleeding brakes. If you get nothing out the system is either dry or that pump is not working.

The return line to the tank should get a nice steady stream of fuel. That is normally one of the first things I check when getting ready to start an unknown machine.

 

[Jayco36REQS]

Hi, Yes I'm talking about the mechanical fuel pumps on the side of the engine....

Let me check the solenoid to see how it is reacting. Luckily I have another running 803a I can compare functions with.

Any good source for finding new pumps?

 

[DieselAddict]

Fleabay is one resource. I just looked and there are some listed. Prepare to have some serious butt hurt on the price though.

If you aren't in a hurry it might be best to have someone go through the ones you have. The devil you know is better many times than the devil you don't. It may be as simple as breaking them down and cleaning them.

 

[Jayco36REQS]

Ok... If I manually depress the plunger with fuel at the input, shouldn't I get some kind of squirt or dribble from the output?

 

[DieselAddict]

Yea, if you have fuel at the inlet and you actuate the pump you should get fuel from the outlet.

 

[jamawieb]

More than likely the plungers are stuck in pump. What I do is take one pump out at a time, then take the tops off (were the hard line hooks to), then soak it in carburetor cleaner for a few hours. Then hold the pump in your hand with the bottom (spring portion) in your palm and squeeze so your compressing the spring and look inside where you took the top off (where the hard lines attach), you should see the plunger moving up and down, every time you compress the spring. If you see it moving, its free. Then you can move the shut off lever, on the pump left and right to make sure that is moving the plunger. You can do everything with the pump still in the engine but you really need a camera or mirror to see the plungers actions. 99% of the time if I get a no start on a low hour unit it's because of the pumps. The plungers have very tight tolerances and any varnish will seize them up. Especially low hour units that haven't really broke in yet.

 

[Jayco36REQS]

Ok.. well looks like its time to get a bunch of carb cleaner and start pulling the fuel pumps out... lol

Thanks guys, I'll give it a whirl and see how it goes. This unit may end up as a parts queen.. lol

 

[Jayco36REQS]

Where is the higher level maintenance manual for the MEP-803a?

 

[Jayco36REQS]

The TM-9-6115-642-24 details testing the external components, but which manual details the engine?

 

[Light in the Dark]

​https://www.steelsoldiers.com/attachment.php?attachmentid=716275&d=1516645270

 

[Guyfang]

Well, so far you all are talking about spending serious money, but we still do not know if the L5 fuel solenoid is moving. If its not working, no start. So whats the deal?

For someone who is into testing 20 gen sets, perhaps you need to be looking into the TM's? The engine Tm is to be found in the TM forum, along with everything you need to work on the gen set. TM 9-2815-253-24 Should be some what you need.

 

[Jayco36REQS]

Guyfang - Yes, the fuel solenoid is working fine... no issues there.

The reason I hadn't found the engine TM is I have not had an issue in 20 units, where it was a fuel/engine specific problem. It's always been either a switch, or sensor, or other electrical issue. Never had to even look at the fuel system other than replace a leaky fuel return line, and put new filters on, and bleed the filters. Ever other one had started up without much issue.

I pulled the #1 fuel pump, and cleaned it, lubed it with wd-40 then fresh diesel... so if I read it correctly, if I apply a fuel supply to the pump input, and compress the fuel plunger by hand, I "should" see some kind of bubble or something on the pump output correct?

 

[Guyfang]

If the IP works right, yes you should see some fuel come out. You could also replace the IP, leave off the line from the IP to the injector, and be able to tell if the IP is putting out fuel, by turning over the engine.

 

[jamawieb]

I doubt your ip is bad, it just has varnish build up from sitting. I have several customers that have 10,000 hours plus on the original injectors and pumps so don't think they are bad. The only time I have had to replace one was when it was leaking into the block. All the others were easily cleaned.
To answer your question on the pump, if its out of the machine and your compressing the spring by hand, you will need to plug the inlet, add a small amount of fuel in the top (where the hard lines hook to) and then press the spring fast and hard to see fuel come out. Its difficult by hand. I clean them making sure the plunger is moving up and down with the compression of the spring and its moving left to right with movement of the fuel cutoff lever. Then put them back in the machine with everything hooked up but the hard lines to the injectors. Crank the unit over and look inside and you will see the pump shoot fuel out the top. Its just going to be a quick shot up, it won't be a steady stream or shoot very far so don't expect much. As long as its coming out, you're good.

 

[Jayco36REQS]

Ok, I cleaned all the injectors one by one, making sure to keep the shim pack in the correct order. They really didn't look bad at all. Just a slight coloration of the carb cleaner residue in the bucket. I use a clear 1-gal bucket cleaning carbs/injectors so I can see any debris or coloring of the cleaning fluid as it runs off the part into the bucket... No debris, and only a slight coloring... so if there was varnish, it was minimal.

Put everything back together, and left the hard-lines to the injectors off... turned on the electric pump, rolled the motor over, and injectors 2, 3, 4 bubbled fuel.. with 4 bubbling the most. #1 injector didn't show any. I've already ordered a new electric pump as I don't like the sound of this one. It flows about 24oz in a min, but thinking it just can't push pressure... and sounds rattly/loose inside. So anyway.. should have a new Airtex E8131 24v pump tomorrow. It should push 5-7psi while the engine is running, so the fuel pumps should have solid positive pressure to the input.

 

[jamawieb]

You may want to try to put the hard lines back on and then try to start. It will take a little while for the air to get out of the lines so don't give up. Try to crank for 20seconds, stop wait about a minute, then try again. Some times it takes 5 or more tries before you'll see smoke coming out of the exhaust.

 

[Light in the Dark]

Yeah plumb it all back together, and let it prime itself for a good five minutes. Try to crank it. Let it prime some more, and crank it. If its gonna go, its gonna go. Its not going to wear the battery down letting a little fuel pump run 5-10 minutes.

 

[DieselAddict]

Yep. Put it together and see if it will start. If you have a syringe and can prime the lines a bit with fuel the process will be faster. Its not necessary though. It is a self priming system.

 

[Daybreak]

Howdy,

NOTE: Word of caution!!!

Make sure you have the quad winding fix applied. Excessive cranking is what zaps the stator.