Help, 802a cranks but won't start. Possible injector pump / rack issue

[Digger556]

Hey all, I've had this MEP-802a for several years now and it has been very reliable. I try to load test every month, but honestly I forget and sometimes it goes 2-3 months between tests. Well I pulled it out yesterday after sitting 2 months and it cranks but won't fire.

Electrically, everything looks good. There are no error lights, the starter cranks hard, fuel pump is running, glow plugs are pulling hard, and the fuel rack solenoid is pulling in like it should.

I pulled the top cover and loosened one of the injector lines and didn't get any fuel out. I gave the engine a small shot of ether and it fired briefly, so valvetrain, pistons, etc seem fine. ( It did run fine when I parked it.) I've verified it has fuel all the way to the injector pumps by removing the rubber line from the injector pump and running the lift pump. (I opened the fuel line at 3 points and opened the bleeder screws on the 2nd fuel filter as well.)

Before I posted, I looked at the TM and performed the air bleed procedure on the forward injector, but no fuel is coming out at all. Not one drip. So now I feel stuck, not knowing what to look at next.

Are there any common problems with the fuel rack that would prevent the injector pumps from pumping?

 

[Light in the Dark]

You might need to take the metering pumps out, if you have fuel there, but not through them. They can be soaked and cycled to ensure they are spraying. I would look at those, before messing with the rack.

 

[Digger556]

You might need to take the metering pumps out, if you have fuel there, but not through them. They can be soaked and cycled to ensure they are spraying. I would look at those, before messing with the rack.

I pulled the forward metering pump, poured some fuel in the feed fitting and covered it with my finger, then pumped the actuator with my hand. I can feel suction on the feed fitting, however nothing was coming out the "fuel pipe end" unless I loosened the "delivery valve holder" more than 1/4" turn.

I reinstalled the whole mess back into the engine and cranked with the delivery valve holder open more than 1/4" turn and saw fuel coming out, but as soon as I retightened it, no fuel came out the fuel pipe end.

Is is possible the fuel pump to moving diesel but not supplying enough pressure? Seems really odd that I would develop a problem with both metering pumps at the same time.

 

[Ray70]

Is the rack moving freely?
If the rack is stuck in the "OFF" position you will not get any fuel through the metering pumps.
If the pin that engages the rack is stuck on either one of the pumps, it will hold the rack in the off position.
If you have 1 pump out now, stick your finger down the hole and feel for the notch in the rack where the pin goes.
pull the plunger into the shut off solenoid, allowing the lever on the side of the engine to rotate clockwise and the fuel rack to move ( on its own ) to the full open position which is towards the generator end of the engine. If you don't feel the rack move on its own, you have a problem.

 

[Guyfang]

You need to remove, take apart and clean the IP's.

 

[cbisson]

Hey all, I've had this MEP-802a for several years now and it has been very reliable. I try to load test every month, but honestly I forget and sometimes it goes 2-3 months between tests. Well I pulled it out yesterday after sitting 2 months and it cranks but won't fire.

Electrically, everything looks good. There are no error lights, the starter cranks hard, fuel pump is running, glow plugs are pulling hard, and the fuel rack solenoid is pulling in like it should.

I pulled the top cover and loosened one of the injector lines and didn't get any fuel out. I gave the engine a small shot of ether and it fired briefly, so valvetrain, pistons, etc seem fine. ( It did run fine when I parked it.) I've verified it has fuel all the way to the injector pumps by removing the rubber line from the injector pump and running the lift pump. (I opened the fuel line at 3 points and opened the bleeder screws on the 2nd fuel filter as well.)

Before I posted, I looked at the TM and performed the air bleed procedure on the forward injector, but no fuel is coming out at all. Not one drip. So now I feel stuck, not knowing what to look at next.

Are there any common problems with the fuel rack that would prevent the injector pumps from pumping?

Since you have seen this unit run well in just the last 2-3 months and now all of a sudden neither IP is delivering fuel to the injectors I would first check the pressure of the fuel feed from the electric lift pump through the filters to the IP's. Doesn't make sense for both of them to get gummed up to the point of not working in such a short period of time. A bad lift pump or clogged filters would effect both IP's as is the case here. The pump may be running and moving fuel but may not be supplying enough fuel pressure.

Just noticed that you mentioned/questioned this in your second post. Have you been able to verify?

 

[Digger556]

Since you have seen this unit run well in just the last 2-3 months and now all of a sudden neither IP is delivering fuel to the injectors I would first check the pressure of the fuel feed from the electric lift pump through the filters to the IP's. Doesn't make sense for both of them to get gummed up to the point of not working in such a short period of time. A bad lift pump or clogged filters would effect both IP's as is the case here. The pump may be running and moving fuel but may not be supplying enough fuel pressure.

Just noticed that you mentioned/questioned this in your second post. Have you been able to verify?

Not yet. It's 0 degrees today, so motivation is a little low. I do have a spare 802a I can swap parts from. I also need to lookup what the proper pressure is from the lift pump.

 

[Ray70]

It depends which pump you have but anything in the >5 psi. should be enough.
You don't need a lot of pressure, but that machine will not without at least some pressure from the pump.

 

[Digger556]

Okay, I pulled the forward metering pump so I could see the rack.

- Pulling the run lever does not move the rack.
- Pulling the run lever and cranking the engine does not move the rack.
- When I pull the run lever and give the rack a nudge, it pops loose and moves back and forth with the run lever.
- If I return the lever to the STOP position, the rack returns to the STOP position and gets stuck again.
- It takes very little force to pop the rack loose, but it will not move from the STOP position by itself any longer.

Is there anything easy to look at? I don't feel the engine is that worn, it only have 207 hrs on the meter and the generator wear looks to match that.

 

[Ray70]

Next thing I would do is pull the other metering pump and try the same test to see if the rack is hanging up due to an issue with the other metering pump.
It is advised to reinstall the first pump before you remove the 2nd, just so the rack stays in position, but honestly I have always taken all the pumps out at once with no issues reinstalling them, you just need to use your finger or the fuel shut off lever to slide the rack to the full left position in order to reinstall.
If you have the same problem even with both pumps removed I would next suspect a problem with the rack being either bent or possibly an issue under the timing cover where the rest of the governor mechanism and the rack lever and springs are located.
Also note: if you have a pump in the motor when trying to manipulate the rack with your finger, the hold down clamp on that pump MUST be at least snug, keeping the pump down against the block. If the clamp is loose and the pump lifts up 1/16" off the block, the pin lever on the pump will rub on the underside of it's mounting surface on the block and cause it to bind up or jam completely.

 

[Guyfang]

Agree 100% with Ray. In fact, I would remove both IP's to see if the rack is in fact the problem. Could be the second IP is the problem.

 

[Digger556]

Okay, a little more progress made, but still not running.

I pulled the 2nd IP and tested the rack. It functions properly with no IPs in place.

I exercised the IPs a bit and stuck them back in. Cranking the engine over with a bit of ether got it rolling fast enough to fire. It was clear it was only running on one cylinder. (Blowing a lot of black, rough and slightly below 1800 rpm)

Shut it down and cracked the injection lines. Fuel coming from the rear line, but not the front.

Pulled both IPs again, disassembled them one at a time, soaking them in Xylene and cleaning any varnish. They didn't look much different, but the piston moved in and out very smooth and easy after. Reinstalled the IPs and ran the bleed procedure per the engine TM. Still no fuel from the forward IP.

I cycled both IPs on the bench and they seemed to be working okay.

Are the lifters under the IPs hydraulic? Is it possible one of them is collapsed and not pushing on the IP plunger?

 

[Guyfang]

Okay, a little more progress made, but still not running.

I pulled the 2nd IP and tested the rack. It functions properly with no IPs in place.

I exercised the IPs a bit and stuck them back in. Cranking the engine over with a bit of ether got it rolling fast enough to fire. It was clear it was only running on one cylinder. (Blowing a lot of black, rough and slightly below 1800 rpm)

Shut it down and cracked the injection lines. Fuel coming from the rear line, but not the front.

Pulled both IPs again, disassembled them one at a time, soaking them in Xylene and cleaning any varnish. They didn't look much different, but the piston moved in and out very smooth and easy after. Reinstalled the IPs and ran the bleed procedure per the engine TM. Still no fuel from the forward IP. (Are you getting fuel to the IP? No output, without input.)

I cycled both IPs on the bench and they seemed to be working okay.

Are the lifters under the IPs hydraulic? Is it possible one of them is collapsed and not pushing on the IP plunger? (No, not hydraulic)

Open to read comments

Please write your city in the location block. Thanks

 

[Digger556]

Open to read comments

Please write your city in the location block. Thanks

I was getting fuel to the IP. I will re-verify since I've had the IPs in and out about 8 times now.

Noted about the lifter.

 

[Digger556]

I "think" I figured this out.

I took the front cover off the engine because the rack was getting stuck again. A little tap on the end freed it up, but it would get stuck occasionally when it returned to the off poistion. With the cover off, I reinserted the IPs again, but watched each one drop into place using a bore scope from inside the block to verify the fuel lever function. Reassembling everything by the book, the IPs appeared to be functioning. I replaced the front cover and bled the system per the TM. The engine fired right up.

I let it run for 30 sec and shut it down. (No belt on at this point to turn the water pump.) I assembled the whole generator back together and tried to fire it up and again nothing. Checking the rack it was getting stuck again. I freed the rack and the engine struggled to start and run. Loosening either injection line caused the engine to lose power. I figured I had not fully purged air from the lines. In the middle of trying to bleed the system, the engine quit firing all together, like something shut off. I checked the rack and it was moving fine, but when I pulled the lines at both IPs, no fuel was coming out again.

That's when I noticed what I believe was the problem. When the stop solenoid released, I could see the rack was traveling beyond the normal STOP position due to its momentum and then snapping back. Here is a slow motion video:

 

[Digger556]

I remembered when I was setting the IPs with the bore scope, if the IP was rotated too far CW or the fuel rack travelled beyond its normal stop, the little fuel levers would come out of the rack slot just enough to jam the rack or worse, would come out of the slot all together, causing them to quit functioning.

With this hunch, I pulled the IPs again, reset them and rotated them fully CCW until the feed nipple hit the pushrod tube. This seem to resolve the racking sticking and lack of fueling issue. (I observed the fuel rack no longer snapped forward as far during shutdown, I think the IPs are now limiting its stop travel as designed.) I re-bled the system and the engine fired right up. This time I let it run for 45 min under load to purge any air. Afterwards I stopped and started it several times to make sure it was still functioning.

I plan to let it sit overnight and try again tomorrow, but so far so good.

 

[kloppk]

Interesting...
I've experienced the same problem with my 802 at shutdown a few times. Have been shutting it down while slowly releasing the fuel solenoid by hand to prevent the problem.

 

[Light in the Dark]

I've got like (3) 802s here that will require rack work (the one I started does not get to full RPM, nor does it shut down properly). Just waiting on some warmer weather...

 

[Ray70]

Metering pump nipple ( fuel inlet hose ) touching the pushrod tube is normally the correct positioning. Apparently moving them too far clockwise causes all sorts of issues in addition to incorrect fuel delivery and trouble shutting down!

 

[Digger556]

Follow on question:

I have restarted this unit cold with ambient temps ranging from 35-65°F. The unit pops right off when I hit the starter, but struggles a bit to climb to 1800 rpm (60Hz). It rolls a decent amount of black smoke for a few seconds, then clears and hits 60hz. From there, it has no issues pulling a 6000 watt load, behaving like it always has.

It didnt do this before, so I'm a little stumped what to do from here.

ETA: It does this on hot restart too,so I don't believe this is a glow plug issue.