MEP-002 rough running

[rickf]

Did a search and could not come up with anything so here is my problem. MEP-002, starts and runs on one cylinder with other kicking in once in a while. Will eventually smooth out and run good only to almost die like a loss of fuel. Will not usually die but struggles to come back, spark knock for a bit, lots of blue smoke and then runs smooth. This will repeat over and over. All filters clean including pumps. Fuel return clean from injectors. Fuel returns to tank while issues are happening indicating good fuel supply. I am thinking it is getting air into the IP but I do not know where or how. Any ideas?

Rick

 

[gimpyrobb]

Sticking fuel shutoff rod? Maybe old fuel fouling injectors? Try adding ATF to the fuel.

 

[rosco]

If its doing the spark knock thing, its because there is, at least periodically, too much fuel. Like it builds up (because its not firing, then when it does fire, there is too much. Maybe two things: one of both valves sticking open... doesn't fire, then they start working again. Check to see if the problem is just on one cylinder. Hold hand on that cylinder area - if its cooler. #2: might be the end of injector itself. May be carboned up. Doesn't atomize fuel - just drips in there till there is too much, then fires/pings, etc. Pull injector & inspect. Brush injector tip with brass brush. I have seen gobs of carbon on the ends of injectors - clean them up. If you can't clean them up, replace. Can make worlds of difference. Good Luck PS Was there any water in the system before? Rust? If so, change filters, yet again!

 

[rickf]

Gimpy, I will watch the rod on next startup but since it does smooth out and run real nice for about 20 seconds and starts the cycle all over again I would not think the rod is the problem. I have never been a fan of ATF in fuel, ATF has a lot of additives that will foul and wear injectors, it is designed NOT to burn. When extra lube is needed I will use 2 cycle oil or usually I use Stanadyne lubricity formula.

Rosco, I don't think it is the valves because of the reason mentioned above, it does smooth out in a regular cycle. Valves would be good or bad. I am going to check clearance though. The tank was clean, no water and fuel is fresh. I will look at the injectors but again, why would it cycle good to bad and back to good almost like clockwork?

Rick

 

[panic_button]

Seafoam at Wally World will clean out & lube dirty injectors and remove any water in the system.

 

[gimpyrobb]

Not sure I understand the "spark knock thing". An mep002 is a diesel.

 

[rosco]

Sticking valves/not completely closing. It misses several firing strokes, then the valves close, too much fuel, and it detonates.

My biggest mechanic lesson when I was a kid - my pickup was missing and the old timer said to check the spark, fuel and air. I said I did! He said, "then it runs"!

Like I was as a Kid... Your missing something! When you check the little stuff and that doesn't get it, you have to stop, sit back and do a thorough, by the numbers, "tune up".

Good Luck

 

[Ken_86gt]

If you have a sticking valve, maybe it will show up on a compression test? Can you do one? Just throwing an idea out there.

 

[rickf]

Not sure I understand the "spark knock thing". An mep002 is a diesel.

It a diesel?!!!!! Dang, that would explain that funky smell in the gas.

Sorry Gimp, That is the best way to describe the sound I am getting.

Rosco, that is where I m headed also is the sticking valves, or a valve too tight and when it warms up it stays open a hair. When it stays open then the misfires and it cools down and maybe closes. LOOOOONG shot but what the heck. Yep, definitely missing something. 40+ years as a master mechanic has taught me to be humble because you will never know it all and the day you think you do............................... You are going to get bit in the arse!

Rick

 

[glcaines]

Some thoughts on your problem- - -

Unless the erratic running is happening with both cylinders, I would think you can rule out filters. I think you can narrow the problem down to one of the following, but not necessarily in that order.

1. IP problem
2. Injector problem
3. Sticking valve problem

When the engine is turning over while starting, does it turn over evenly, or does it sound like the RPM is changing? If a valve is sticking in the open position, the engine RPM will increase when the piston for that particular cylinder comes up on compression. That is, unless a valve is sticking only at higher RPM. Another question is how long are you letting it run? I would let it run a while and check the temperature of the cylinders to determine which cylinder is cutting out. If you don't think it is a sticking valve problem, the next step is to rule out the injector.

 

[rickf]

Gary, I am pretty sure it is the injection pump but I am going to rule out the easy stuff first. It is raining here today so I will not get anything done on it today. It does drop both cylinders at times. Being a long time mechanic I know the sound of no compression on cranking and I don't have that. I am sure it is a fuel problem which is occurring after the filters. That would pretty much pin it to the IP. It is almost like it gets a big gulp of air and then has to purge the air before it will run smooth again. It will run smooth on both cylinders for about 15-20 seconds and the whole cycle starts over again. There is return flow to the tank the whole time so I don't think the feed pumps are the problem. This was also run straight from a can of clean fuel bypassing all of the filters and lines and the problem was identical. That is why I am discounting the main fuel system of the gen-set itself. I just don't understand what could be happening inside the IP that would cause this to happen. Is there a filter integral in the IP?

Rick

 

[glcaines]

Rick,
I'm not an expert on the MEP-002A. I have an MEP-003A, which has a lot of similarities. I don't think there is a filter in the IP, but I could be wrong. If you are certain that it is missing on both cylinders, there is still the possibility that the IP is pulling in some air some place that is hard to find. Are you certain that the fuel cut-off might not be erratically cutting fuel off and on? On my MEP, the fuel cut-off occasionally sticks and I have to manually exercise it with my fingers to clear it up. I've tried all kinds of solvents, etc. and finally decided to just keep doing what I have been. You might want to try manually pulling and pushing the fuel cut-off at the IP while the engine is running and see what happens.

As far as testing for an air leak, the only way I know is to Pressurize the entire line from the end of the intake line to the IP and spraying soapy water on it to look for leaks. It would be terrible to spring for a new IP only to find that you still have the problem. Good luck with your troubleshooting.

 

[Felix357]

It sounds alot like what my 002 was doing. I worked with Tom at Gulf Coast Trucks to diagnose the problem. Finally it came down to the IP being my problem. He advised me against pulling the injectors, due to the cooling fins being very easily broken trying to get them out of the head. Once broken, the injector will have to be replaced. And In all of the military gen sets he has worked on, he has only seen 1 bad injector. So I had him rebuild my IP, since he does function test it before sending it back and also provides a warranty. When he did the function test after the first rebuild, it still had the same problem. When Tom pulled it apart the second time he found the plunger guide (the small part that attaches the drive gear to the hydraulic head) was broke in 2 pieces. He replaced the plunger guide and it now runs like a champ. Since he missed it on the first rebuild, the only think that he can come up with is that the guide was broke only half way. Which allowed the guide to spread out just enough for the plunger to spin in the guide (cylinder miss) and then catch again (normal operation) until it spreads open again.

 

[rickf]

Felix, can I ask what it cost to rebuild?

Rick

 

[Felix357]

350 plus parts, the guide was only about $15. However, if the plunger shaft is rounded off then it's major $$. Ambac is proud of it and you have to buy the entire assembly. The shaft is hardened and the guide is supposed to fail first, but the shaft can ware.

 

[Speddmon]

Just a little off topic, but the more I hear about this dude in Texas, the more I think I'll steer clear of him. To start with, he's told several people on the board here to re-use their old timing buttons when they put a new injection pump on their engine...which even according to the manufacturer of the pumps is wrong. Now he's telling you not to pull the injectors because if you break a cooling fin you need to replace the injector. First off, those fins have absolutely nothing to do with the proper operation of the injector, and as a matter of fact, if you look at figure 46 of the -24TM for the -003a, you can clearly see it is a seperate part all together. Granted, if you break all of the fins off of the injector, you may loose a little bit of cooling for the injector because they act as a heat sink for the injector. But I highly doubt that an injector has ever melted down because of a broken cooling fin. You'll still get plenty of air flow across the injectors from the fan blowing air across the heads.

 

[storeman]

I'm going through similar issues with a MEP-002a. Mine will now run continuously and carry about 4500 watts while blowing heavy blue smoke.

Adjusted the valve clearances, timed the IP and finally have it running with the heavy blue smoke. Have pretty well narrowed it down to injectors opening at too low pressure and will adjust them in the next couple days and report back. Will also recheck valve clearances.

Runs with 4500 watts, bogs down with 6000 watts.

Jerry

 

[Speddmon]

Jerry,

If you are pumping out heavy blue smoke, I would be looking at doing a compression test before I looked at injectors. Blue smoke is typically oil and not fuel. I think you may have some bad rings or bad valve seals.

 

[storeman]

Thanks Tom. Will do.

 

[Ray70]

Hello guys, I know this is a very old thread, but I'm wondering your thoughts on a similar issue I'm seeing on an 002A I fired up for the first time last night.
I did all the filters, flushed it all out and put in fresh fuel with some seafoam and ATF.
Unit is very clean with only 8 hours on it since " Overhauled" in 1992.
It starts easily, runs very clean and takes a 4500 watt load with no problem. ( haven't tested any higher load yet ) While running I can hear an occasional dip in RPM ( also noticed on my kill-a watt as a 1-1.5 HZ droop for about a second or less ) where the motor stumbles for just a fraction of a second, then recovers.
Watching the governor arm, you see it lift up for a fraction of a second, then back down again.
This stumble probably occurs 1 or 2 times a minute, maybe less.
Exhaust is perfectly clear except for a tiny puff of black ( only visible under close inspection with a light ) right when the machine recovers.
I'm set up to test injectors and rebuild IP's myself, so looking for your thoughts as to the most likely culprit.
Also wondering if anyone has experienced a similar problem and if an air leak on the suction side of the fuel system could cause this. I noticed the suction line was loose at the tank when I went to prime the new filters and the fitting seems to have tightened up, but looks oddly crooked where the line meets the 90 degree fitting at the top of the tank.
Also noticed it seems loud inside the air cleaner with the end cap removed. ( possibly a sticky intake valve ) but sounds normal with cap on, and I have never run one with the cap off before....

Thanks.. Ray