MEP-802A Injection Pump issue

[Rebel635]

Working on an MEP-802A. This ones got me stumped a bit.

Added all liquids, batteries, can hear both aux and primary fuel pumps run on the appropriate switch. Bled the secondary fuel filter, cranks but no start.

Crack injector line and no fuels coming out. Fuel shut off valve solenoid is functioning fine. Removed injector line from injection pump, no fuel coming from injection pump.

Reference TM on injection pump removal and it specifies to move the fuel shutoff valve fully counterclockwise and zip tie before removing pump. No joy....I disconnected the solenoid and the lever going into engine has very little resistance. I checked my other known working MEP-802a and i can feel resistance in lever like its moving something spring loaded. This one, nothing, almost stays where you put it, it has very little tension to return counter clockwise.

With that being said, the Injection pump is not coming out, so far i only tried the left one (closer to rad) but its not budging. It rises a few mm and thats it. I think somethings busted internally. I think the reason the pumps not coming out is because the fuel shutoff has no resistance = something internally busted.

Does this mean that the whole fuel metering thingy will have to come off the engine? Will i have to take the crank pulley off? Rad, entire back of the enclosure off?

 

[Rebel635]

Nothing? No-one?

 

[rustystud]

Sorry Rebel I have not worked on a MEP-802A yet so I cannot give any definite answers, but I have heard that the injector rail system can come loose and cause all sorts of problems. I would defiantly read up in the TM's and see what they say to do to remove the pump assembly.

 

[zarathustra]

It is unlikely that something inside is broken. So, you can be happy about that.....

But, one (or both) pump(s) is (are) stuck. If a pump is stuck, it will prevent the fuel rail from moving backwards and forwards. Each pump has a tang on it that rotates. Since the tang is inserted into a slot on the rail, if the pump won't rotate, then the rail doesn't move no matter where the fuel lever (fuel solenoid) is. Only one has to be stuck to prevent both from rotating.

Thats a solvable, but nasty little problem. It is more likely to happen if the generator is a low hour unit.

when moving that fuel shutoff lever backwards and forwards you should feel a little resistance and hear the rail going backwards and forwards. If not it is a stuck pump.

There is a piston inside the pump which goes up and down and rotates. It can be rotated by the fuel shutoff lever being moved back and forth, and it will move up and down as the engine is rotated. There is a groove cut into the side of the piston, so you can see if it rotates by watching the groove.

If you rotate the engine, do it by hand and not via the starter motor.

I usually do everything I can to try to budge it loose without removing the pump.

If you take the top half of the pump off and carefully remove the inside of the unit you can get down to the pump piston.
There is a small one-way valve and a tiny thrust washer to take out; I generally use a set of hemostats to remove them. A magnet might help on the washer...

The only way to see the piston is to use a camera.

So I have used lacquer thinner, Marvel mystery oil (not at the same time) to try to budge the piston loose. There are no "O" rings or anything in that pump, so the thinner should be OK.

You can take the top half off of both pumps at the same time, and by moving the fuel shutoff lever you can see if either of the pistons try to move. If one looks like it "wants" to move, the other pump is likely stuck. You can also try rotating the engine after the lacquer thinner or MMO has some time to work, and that might budge it loose.

Keep trying.

If you can't get the piston loose, then it is time to remove the unit. Re-install the solenoid so that the fuel shutoff lever is at its stops (maximum CCW).

At that time, remove the fuel line to the pump and rotate the pump as far clockwise as you can. If you are luck it should come out easily after some wiggling. If the pump froze up with the solenoid installed then you should be lucky. If the pump froze up with the solenoid not installed then the problem just got harder.

Some pumps have the fuel port swaged into the unit, and some have it screwed in. You'll know this if there is a hex head on the inner part of the port. I'd avoid this if possible, but you may have to go as far as removing the port, assuming that you have one with the hex screw in feature. With the port removed you can move the pump even further clockwise.

If you have the swaged in port and the unit froze up with the solenoid disconnected then, well, keep trying to break it loose. I'm not sure there is a non-destructive method for getting the pump out in that situation.

I would also try to turn the engine so that the pump piston is in the down position rather than the up position when trying to remove it.

Once out, keep the shims and re-install with the shims.

Once out, you can work the lever (tang) on the pump to make it unit rotate. If it is really, really stuck then you might have to take the piston out. There is a rectangular piece that holds the piston in the pump that consists simply of some metal on the pump housing bent over just a little (like a tab) that interferes just enough to keep the pump together. Once installed in the engine the tabs don't do anything 'cause the engine itself keeps the piston up enough to keep it from reaching the tabs.

With the piston out you can clean it up with some chrome polish -- also clean out the inside of the cylinder with some polish and a Q tip. I usually lube it up with some light oil after it is re-assembled.

BEFORE you remove the piston, note the relationship between the groove in the piston and the input port. It is possible to assemble the pump with the piston 180 degrees out, but if you do, the relationship between the port and groove will be way off, so it is easy to tell.

I'd remove the pumps only as a last and final resort.

After you get the pumps installed I'd recommend running the engine for a while to make sure that the piston(s) get well lubricated by the fuel oil.

Oh, the upper part of the pump that houses the one way valve that you took out before you removed the pump --- it should come apart into two pieces. If it, too is stuck then it needs to be freed up. With any luck, that is the root problem and the pump is free to operate!!

One last thing... I'd take it apart as little as I could to make it work. I wouldn't do any extra disassembly that wasn't absolutely required after having exhausted all other avenues.

Good luck

 

[Rebel635]

My god man, what an amazing post. Thank you so much

Looks like i got ANOTHER genny with the same issue. I can get fuel to dribble out of the top of the pump during cranking. You take the line running to the cylinder out and crank and you'll slowly see the fuel swell up and rise to the top of the pump before spilling over. Nothing like the jet of diesel that is needed.

I took top of the pump off, a steel cylinder with an internal piece came out, both pieces exasperated. I take it i can now just glimpse the piston?

Unfortunately both units have the fuel intake ports swagged so no luck screwing them out.

I'll go get some lacquer thinner tomorrow.. Everything is closed right now.

Thank you for giving me an understanding of whats happening.

 

[zarathustra]

Don't give up trying to get a pump out. Once one is out, you can manipulate the rail with a screwdriver to force the second pump loose (a little anyway). You just have to get them rotating a little. Once they start rotating the fuel pressure and vibrations will set them free.

Best of luck in a difficult situation. Just remember that all you need is a little rotation and the pressures within the unit will force the pump to work. Once you can get the pumps to work once, inertia will get them both moving. The unit will smoke up a storm, but once running for 5 - 10 minutes you will think you have a brand new unit......

Keep us informed on progress...

Best of luck

Z

 

[Rebel635]

UPDATE!

Okay, the trick to removing the IPs: Unhook everything off both IPs so they can both spin free left and right. Then like safe cracker, rotate both IPs, fiddling around until you find the sweet spot where one of the IPs will slide out. IPs can jam one of two way. They can either jam in the left and right hook movement, or on the vertical axis. Most likely both. Two of the IP's had their springs fully compressed.

NOTE: While there is no o-rings and such in the actual IP, the check valve system on top, which uses a 19mm wrench to take off does have a green o-ring that will swell up in lacquer thinner. Remove the housing with the o-ring off and do not expose to thinner.

I found soaking in lacquer thinner doesnt really do much if the spring is compressed. Just cant seem to seep all the way down.

I ended up taking apart all 4 pumps. Here's how i did it. If the spring was compressed i'd use a brass punch to gently knock the rod out and release the spring tension. Dont go nuts here as if you knock it too far it will bend the rod keeper tabs out and the rod will eject out the bottom. Not a major disaster unless you cant find the parts again.

Probably the hardest part will be to compress the spring and move the spring captive washer to the side where it will release. Need three hands for that.

Once you release the washer the spring will come out as well. At this point there is a C-clip that has to be taken out that will release the spring seat and "throttle" lever. This throttle lever is what rotates the rod and changes amount of fuel that will inject.

Carefully lift the lever off and immediate note the position of the notch on the rod. Its paramount that it goes back in facing the right way. Once the lever is out, gently knock the rod the rest of the way out. At this point dump everything in lacquer thinner for a bit then wipe off. The metal bushing that the rod rides in will only fit back in one way. It has a channel cut into it that a rod on the IP body fits in.

NOTE: Lacquer thinner will eat all the green paint of the IPs so make sure to wipe it all off before reassembly to make sure none of it gets back in.

You'll fiddle with the parts for a bit until you learn how to reassemble but its opposite of dissasembly. I found an m5 bolt in the metal bushing stops the rod from falling through while trying to attach the spring on the back side. Thats when the IP is upside down in the vice so you can compress the spring.

FINAL NOTE!

So i reassembled the pumps, put them back in one of the MEP's and still wont fire. The shut off lever still feels like there is nothing touching it. The other MEP i reassembled but not fired up i can feel resistance in the lever. Will have to play with the first MEP and find why the rods not moving.

REQUEST!

Anyone know where to find individual IP parts? I've somehow managed to misplace the check valve for one of the pumps. I swear it grew legs and walked off.
The little fat metal piece with the opening in the middle and the weird looking piece that fits through it.

The highlighted parts

 

[rustystud]

Rebel, it would be great if you could post those pictures to this site. So many pictures get lost once a person leaves here or closes there photobucket account. So for future people seeking help this would be really helpful.

 

[Rebel635]

I made an album, uploaded the picture, but when i go and select the album it says "This album has no pictures"

Whatever, I've discovered that the proper name for my lost thingymajigy is a "delivery valve", but lister-peters doesnt list delivery valves for the LPW2 engine.

I did find the entire injection pump is part number 751-41322. Green Mountain Generators is asking $238 when across the pond they are going for 30 Pounds....Guess where i ordered it from?

Oh, i got first genny running. It seems when i installed IP #2 the selector rod didnt go into the rack slot but pressed down on the rack trapping it. Reinserted the pumps, made sure the rack is free to move and she fired right up.

Also, I was petrified to remember that i removed both my IPs at the same time seeing the warnings that doing that would require the front of the motor to be taken off so the rack can be put back into position. This is not true.

In fact i've had both pumps off numerous times and used my fingers to slide the rack back and fourth and to position it in the proper spot for the pumps to drop in.

 

[rustystud]

What company did you order the parts from in England ? That is information we all could find useful.

 

[Rebel635]

http://www.stationaryengineparts.com

they only showed one in stock, but Uk ebay seems to have much more lister peter parts

remember kiddies the 802a uses an LPW2 engine.

 

[zarathustra]

Well, it is always good to hear a successful story.

Congratulations on your IP fix.

 

[Rebel635]

All possible due to your detailed explanation.

Once again, thanks

Well, it is always good to hear a successful story.

Congratulations on your IP fix.

 

[Bmxenbrett]

did you end up having stuck check valves? my pumps work with out them installed. I took them apart and don't see any damage or crud in there, I sprayed everything clean with brake clean and still nothing....does anyone know if they sell just the top check valve part of the Injection Pump?

 

[Grizzlypower2001]

Good question, I tried bench testing my IP's on a bench and had no luck. I bought one "out of a running engine" from eBay and two from a seized motor. I had an injector and a spare pump still no luck. Reading this post interested me to try again. I just wanted to test the parts for "working spares". From the pic, it looks like you can service or take apart the check valve? Also any idea how much pressure will it take the check valve to open?

Thanks again guys for all your help!

Sent from my XT1254 using Tapatalk

 

[Rebel635]

If they do, i havent been able to find it. I ended up buying an entire IP just to take the check valve off of it....

Check valves are there to stop bleed down and so you dont have to crank for a long time to pressurize the system....the also maybe used to maintain line pressure so the next IP squirt uses hydraulic pressure to fire the injector?

Easy way to find out....

did you end up having stuck check valves? my pumps work with out them installed. I took them apart and don't see any damage or crud in there, I sprayed everything clean with brake clean and still nothing....does anyone know if they sell just the top check valve part of the Injection Pump?

 

[CallMeColt]

Great post with a lot of information! Thank you.

I'm currently trying to troubleshoot a leak at my injections pumps. It's leaking from where the injector meets the shims. Any ideas?

I read that there is an o-ring in the injector pumps... maybe that is bad? I had a lot of issues with fuel return lines going bad. Maybe I just need to replace those o-rings?

EDIT: After an hour on the Google, I found Lister Petter part number 751-12842. It's an injection pump gasket. Might be the issue.

For anyone else who finds this post & is troubleshooting the same issue, here is a link to me thread. It should bring you right to my first post about the injection pumps;
https://www.steelsoldiers.com/showt...ix-up-Thread&p=2212610&viewfull=1#post2212610