803a fuel rack sticking problems, are there options before pulling the covers off?

[Demoh]

So I am working on an 803 that has me a little stumped. I dont mind being stumped for as this is good brain exercise but I am hoping to see if anybody has a solution before I open the engine up to investigate (I prefer to not use consumables if I dont have to.) Unit was a non-runner picked up. From experience after seeing no-fuel and working on one of my waterlogged units I expected a stuck rack so after pulling the plug on the front cover the rack was indeed stuck. As soon as I touched the rack with the fuel shutoff solenoid pulled back the rack sprung into place and the unit ran for a bit. When I say a bit I mean I ran it long enough to gather some data and make a parts list. I threw this unit on the shelf for a few months while moving shops and traveling and life figuring I would circle back around to this one when I had more time.

Well fast forward some months I pulled it from storage and did my pre-trip and fired the generator up, but it involved draining the tank and putting just enough fuel in for the pickup tube. (knowing low fuel alarm would kill the gen if I didnt battle short it after start). The generator fired up to speed, stalled, caught and got up to speed again, then stalled. My first thought was oops forgot to hold start until oil pressure built.

Wouldnt restart. I pulled that inspection plug and the rack was stuck again. Unstuck it and fired it up again, it did the same surging as it did before.

I pull the injection pumps one by one. First this was no small task as either A) they are the wrong pumps / bad batch / something, as I had to double wrench the hard line nuts off of the injector pumps the ENTIRE length of the threads. I mean if I didnt know any better I would have thought they were all cross threaded and impacted on. I compared the threads with the other pumps I have laying around and the threads are the same except for diameter. The threads are bigger but I dont know why, did somebody tighten these down so tight that the bubble on the hard line caused the threads to expand? I dont see any evidence of that. This set came from albany however the engine had a tag from a company that ive never seen on a set out of there (aka commercially rebuilt / sourced maybe?) and the set engine looks like it has ZERO hours on the engine instead of the 2 hours all of the rebuilt ones have; the exhaust manifold paint is beautiful, shiny, and not any of it burnt off so that leads me to believe this set never ran. (but it is also different green paint than the normal sets ive seen out of albany/chamberburg)

Aside from that the pumps appear to function and freely move. I spend roughly 2 hours with the set manipulating the fuel rail with my hands in the engine like a raccoon trying to open a trap. I ended up disconnecting the solenoid to aid in troubleshooting. what I found is this:
1) with no pumps installed I cannot get the rail to stick within "normal travel ranges".
2) with 1, 2, 3, or 4 pumps installed, if I gently alternate between stop and run with the problem doesnt occur.
3) with 1, 2, 3, 4, or 1 or 2 known good pumps installed and I "snap" the linkage from run to stop, theres a 50% change the rail will stick in the stop position.
4) using a screwdriver through the access it is hard to unstick the linkage at times. The easiest method to unstick is when you have 1 pump out and you reach in and wiggle the rail up and down. side-side doesnt really free it but up and down does (basically rotating the rail ever so slightly)
5) when the pumps are installed they are infact installed with the pins captive in the rail. I am able to detect when I miss the slot.
6) all pumps are torqued down because when they arent the metering lever is very hard to move due to spring tension.

So what I have determined is when the rail over extends itself when to goes from run to stop, the metering levers on the pumps go fully as well, but the angle of which the rail is pushed combined with the angle of the metering arm on the pumps creates a condition where the springs controlling the tension on the fuel rail cannot overcome, even with only 1 injector pump. Its like there is a friction between the pin on the metering arm and the rail is very great and it doesnt slide very well. But why it does this is the question I am with right now.

When I say the rail over extends, the resting place of the rail when the linkage is in the stop position and when the rail is stuck is not the same. When it is stuck it is roughly 1/32 further forward. Enough where if I adjusted the stop that it wouldnt matter because the problem would still exist because I could 'bounce' the rail forward manually with my hand or if the linkage was connected to the solenoid the spring would have enough force to do that on its own.

Is there an additional spring that might be missing in the governor assembly, or is it an adjustment, or maybe excessive corrosion? Spring tension 'seems' normal when compared to other sets because I have small enough hands to be able to manipulate the rail through the pump holes, but without having it apart with a working unit next to it it is a guessing game right now. Is there anything I'm not seeing with this unit or are these findings enough to warrant tearing the covers off to investigate further?

Also one thing I noticed but probably unrelated: The solenoid linkage that is on the governor case. when going from run to stop it is supposed to slide the fuel rail towards the front of the engine. It does this however when it does the rail moves forward halfway, 'slips off' and returns to closer to run position and then catches on a second 'notch' on the linkage which will eventually bring the rail all the way to the stop position. I havent tested this with other sets but I think this is how it normally operates even though it seems odd on why it 'ratchets'.... maybe its to make sure the linkage is free and clear of the rack so that it doesnt interfere with the governor during normal operation.

 

[USAMilRet]

No spring missing. Purely adjustment. The "stuck fuel rail" was a known issue. That is why I wanted the special tool that keeps the fuel rack in place during rebuilds.

The top flat screw needs to be turned out a couple of flats (the fuel cutoff lever/cam) so that a stuck rack does not occur.

There is a TB in the manual section pertaining to this with the 802a but is valid with the 803a.

As an add on: you can try removing the threaded plug on the gear end cover (droop adjustment cover) and try to manipulate the fuel rack from there. I had success doing this.

 

[kloppk]

USAMilRet - I sent you a PM...

 

[USAMilRet]

Sorry.....replied to.

Demoh:. It is in the Injection Pump Procedure PDF. You have to adjust the rack to prevent the stuck rack from happening. If the fuel cam screw is not turned out sufficiently, you can get the stuck rack because of all the things you noted in your post.

Once I had my fuel pumps installed, I could feel the fuel stops hitting the rack when I rotated the shutoff cam cc. The key is to feel at that instant where the fuel stops are then adjust the screw out until it just touches the top of the cam, then screw out an additional 2 flats of the screw. This will prevent any further stuck racks. Adjust the lower screw so that there is 26mm distance from the top screw to the top of the fuel cam where it interfaces with the flats. Screw out the lower screw until the proper interface is achieved.

 

[Guyfang]

You guys are getting better every day!

 

[Ray70]

To answer your question about the ratcheting linkage, that is completely normal. Not sure of teh exact reasoning for it, but normal none the less....

 

[Demoh]

Thanks all, once I get back to it ill adjust and report back.

Curious on people's opinions on the pump to hardline being tight, like needing to double wrench the nut off the entirety of the threads. I just measured the pumps from this unit (major thread OD) and they are 0.475. Measured a pump from a unit which I can thread the nut down most of the way by hand and its 0.465. Minor OD is within .001 of each other so it doesnt "seem" like the nut was ran down so tight that it expanded the threads since its a reverse flare/ball. Threads look excellent, no galling, scoring, nicks or dents, etc... Chock these up to manufacturing differences?

For sake of being thorough part numbers are lister 751-41173 genuine from 1994 which threads fine (on both engines) and lister 751-41175 with an S stamp (stanadyne) from 2004 which threads onto nothing by hand.

Im just going to run a die on them and hopefully call it a day because there is no way I could willingly reinstall as-is.

 

[Demoh]

Just to follow up to this. This generator was one of the 10kw units I hauled up to panama city (and a bag of parts, spares, manuals, tools, etc..) because I really needed to get on the road ASAP after the hurricane hit. With how the situation was up there I was prepared to fabricate my own fuel rail stop through the adjustment port because **** was kind of hitting the fan.

I reinstalled the pumps as I have many times, confirming the tab was in the notch in the fuel rail and all that jazz, and did the exact same thing to reproduce the jam without any incident. After adjusting the pumps to output even temperature this engine was able to get it's real first run; the unit went though an incomplete reset and did not get it's "2 hour" test as evidenced by the bright green paint on the exhaust manifold.

The definition of insanity is now invalidated as I have tried the same thing over and over again and finally achieved different results.

Sidenote, the way the fuel rail was sticking and the fuel rack adjustment procedure seems to be not what was happening. The adjustment procedure has you work on the top set screw (60) but the problem I was trying to solve never occurred by shutting the unit down. The set screw only allowed the fuel rack to move so far, but the problem was when the fuel rack over-extends that travel. Keeping in mind the fuel rack can over extend but the lever cannot because the lever has a set screw but the rack the only thing holding it to the lever is a spring, and something in this gen was making the fuel rack "jump" past the point of no return. This was reproducible until the weeks before bringing the generator up north but ceased the moment it was dropped off and slapped together.

The amount of confusion and head scratching is high with this one. Unit ran great for upwards 150 hours since it was put back together without incident (after cleaning S8 ).... But hey, it works. Its hard for me to not lose sleep over this one though.

 

[majoday]

So I am working on an 803 that has me a little stumped. I dont mind being stumped for as this is good brain exercise but I am hoping to see if anybody has a solution before I open the engine up to investigate (I prefer to not use consumables if I dont have to.) Unit was a non-runner picked up. From experience after seeing no-fuel and working on one of my waterlogged units I expected a stuck rack so after pulling the plug on the front cover the rack was indeed stuck. As soon as I touched the rack with the fuel shutoff solenoid pulled back the rack sprung into place and the unit ran for a bit. When I say a bit I mean I ran it long enough to gather some data and make a parts list. I threw this unit on the shelf for a few months while moving shops and traveling and life figuring I would circle back around to this one when I had more time.

Well fast forward some months I pulled it from storage and did my pre-trip and fired the generator up, but it involved draining the tank and putting just enough fuel in for the pickup tube. (knowing low fuel alarm would kill the gen if I didnt battle short it after start). The generator fired up to speed, stalled, caught and got up to speed again, then stalled. My first thought was oops forgot to hold start until oil pressure built.

Wouldnt restart. I pulled that inspection plug and the rack was stuck again. Unstuck it and fired it up again, it did the same surging as it did before.

I pull the injection pumps one by one. First this was no small task as either A) they are the wrong pumps / bad batch / something, as I had to double wrench the hard line nuts off of the injector pumps the ENTIRE length of the threads. I mean if I didnt know any better I would have thought they were all cross threaded and impacted on. I compared the threads with the other pumps I have laying around and the threads are the same except for diameter. The threads are bigger but I dont know why, did somebody tighten these down so tight that the bubble on the hard line caused the threads to expand? I dont see any evidence of that. This set came from albany however the engine had a tag from a company that ive never seen on a set out of there (aka commercially rebuilt / sourced maybe?) and the set engine looks like it has ZERO hours on the engine instead of the 2 hours all of the rebuilt ones have; the exhaust manifold paint is beautiful, shiny, and not any of it burnt off so that leads me to believe this set never ran. (but it is also different green paint than the normal sets ive seen out of albany/chamberburg)

Aside from that the pumps appear to function and freely move. I spend roughly 2 hours with the set manipulating the fuel rail with my hands in the engine like a raccoon trying to open a trap. I ended up disconnecting the solenoid to aid in troubleshooting. what I found is this:
1) with no pumps installed I cannot get the rail to stick within "normal travel ranges".
2) with 1, 2, 3, or 4 pumps installed, if I gently alternate between stop and run with the problem doesnt occur.
3) with 1, 2, 3, 4, or 1 or 2 known good pumps installed and I "snap" the linkage from run to stop, theres a 50% change the rail will stick in the stop position.
4) using a screwdriver through the access it is hard to unstick the linkage at times. The easiest method to unstick is when you have 1 pump out and you reach in and wiggle the rail up and down. side-side doesnt really free it but up and down does (basically rotating the rail ever so slightly)
5) when the pumps are installed they are infact installed with the pins captive in the rail. I am able to detect when I miss the slot.
6) all pumps are torqued down because when they arent the metering lever is very hard to move due to spring tension.

So what I have determined is when the rail over extends itself when to goes from run to stop, the metering levers on the pumps go fully as well, but the angle of which the rail is pushed combined with the angle of the metering arm on the pumps creates a condition where the springs controlling the tension on the fuel rail cannot overcome, even with only 1 injector pump. Its like there is a friction between the pin on the metering arm and the rail is very great and it doesnt slide very well. But why it does this is the question I am with right now.

When I say the rail over extends, the resting place of the rail when the linkage is in the stop position and when the rail is stuck is not the same. When it is stuck it is roughly 1/32 further forward. Enough where if I adjusted the stop that it wouldnt matter because the problem would still exist because I could 'bounce' the rail forward manually with my hand or if the linkage was connected to the solenoid the spring would have enough force to do that on its own.

Is there an additional spring that might be missing in the governor assembly, or is it an adjustment, or maybe excessive corrosion? Spring tension 'seems' normal when compared to other sets because I have small enough hands to be able to manipulate the rail through the pump holes, but without having it apart with a working unit next to it it is a guessing game right now. Is there anything I'm not seeing with this unit or are these findings enough to warrant tearing the covers off to investigate further?

Also one thing I noticed but probably unrelated: The solenoid linkage that is on the governor case. when going from run to stop it is supposed to slide the fuel rail towards the front of the engine. It does this however when it does the rail moves forward halfway, 'slips off' and returns to closer to run position and then catches on a second 'notch' on the linkage which will eventually bring the rail all the way to the stop position. I havent tested this with other sets but I think this is how it normally operates even though it seems odd on why it 'ratchets'.... maybe its to make sure the linkage is free and clear of the rack so that it doesnt interfere with the governor during normal operation.

Thanks for posting this. It helped me to better understand how this part works. really helpful!

 

[BrentN]

Sorry.....replied to.

Demoh:. It is in the Injection Pump Procedure PDF. You have to adjust the rack to prevent the stuck rack from happening. If the fuel cam screw is not turned out sufficiently, you can get the stuck rack because of all the things you noted in your post.

Once I had my fuel pumps installed, I could feel the fuel stops hitting the rack when I rotated the shutoff cam cc. The key is to feel at that instant where the fuel stops are then adjust the screw out until it just touches the top of the cam, then screw out an additional 2 flats of the screw. This will prevent any further stuck racks. Adjust the lower screw so that there is 26mm distance from the top screw to the top of the fuel cam where it interfaces with the flats. Screw out the lower screw until the proper interface is achieved.

Can you point me to where the Injection Pump Procedure PDF is. I have an MEP803 and am having problems getting Injection Pump #2 back into its bore and lining up with the rack. The other 3 arent a problem. The Injection pump wants to sit on top of the rail and then keeps the rail from actuating.
Thanks,
Brent

 

[Ray70]

Is the metering pump giving you trouble even after it is clamped down, or is the hold down clamp loose?
If the cam lobe is pushing up on the pump at all, the lever on the metering pump will hit on the underside of the engine block casting and jam up the rack.
if the clamp is totally loose, try tightening the clamp down until the pump is almost seated and see if the lever is free.
If it's free go ahead and tighten the clamp the rest of the way.

 

[BrentN]

Is the metering pump giving you trouble even after it is clamped down, or is the hold down clamp loose?
If the cam lobe is pushing up on the pump at all, the lever on the metering pump will hit on the underside of the engine block casting and jam up the rack.
if the clamp is totally loose, try tightening the clamp down until the pump is almost seated and see if the lever is free.
If it's free go ahead and tighten the clamp the rest of the way.

Hi, Thanks for responding.
I havent tried starting the engine yet. I am just not convinced #2 Inj pump is installed correctly.

I have the other 3 injection pumps installed and the rack slides easily back and forth. When I install #2 Pump it doesnt drop into the hole easily like the rest did. It sits proud of the block by probably a 1/4 inch. In order for it to sit flush on the flange, the clamp has to be used to force it down.

When I move the fuel control lever it does feel like it is moving the #2 Pump lever (before I tighten the holdown clamp) ...But I dont know for sure.
When I clamp it down tight, I pull #4 Inj pump and the rack isnt moving. My thought is that maybe the slot isnt accepting the pump lever and and it is bending the rack down and binding it.

My sympton is that hadnt been getting any fuel to the injectors and I have plenty of fuel to each of the Inj pumps. This generator has been off line for awhile (long story about a barn crashing down on top of it and I am just now getting around to trying to get it restarted now that I have a new barn)

The generator ran fine 3 years ago, but I may have disturbed the Inj pumps when I was re-hosing it and I cant recall, I may have been pulling injection pumps before I realized the importance of the rack and lever. (I know, dumb move). After that, I couldnt get it to light.

Since I couldnt get any fuel up to the injectors, I am thinking I bound up the rack and the injector pumps are in the closed position.

In looking at your comment about the cam lobe, that for #2 is much higher than the rest...Perhaps I should turn the engine slightly at the crank pulley and then that lobe will rotate and allow me to drop that Pump in easily. The more I think about it, that may be the issue...if that pump arm is binding up on the block with cam lobe up high.

 

[uniquify]

If you take the #2 pump out, are you able to move that pump's metering lever back and forth easily? If not, that pump might be seized, which would prevent the fuel rack from moving when that pump is installed.

Or another thought would be to use the dead crank switch to bump the engine over, so you can verify the cam lobe under the #2 pump is in the down position before installing the #2 pump.

Here are pics that show the movement of the metering lever.

 

[Light in the Dark]

I would pull all 4 metering pumps out and test each for ease of rotation of the pin assembly (as shown above). To do this properly, you need to back the top set screw off a bit (so when the fuel rack is fully pulled left, it can go slightly more left). Pull all 4 out and test (remember location preferably, as they may feature shims pertinent to each position). Test for rotation, as well as pump them with your hands, to see if they do spray any fuel. Wouldn't hurt to leave them submerged in carb cleaner for a few days if you have the time).

If all rotate fine, and spray OK under compression... easiest thing to do is to hand articulate the fuel rack (from the outside) with your left hand to the right, and place a finger into the pin hole on the cylinder closest to the radiator. You will feel the groove which that first pin should go into. Drop the first pump back in so the pin lines up, and tighten it down with the keep and nut so the rack is now properly aligned. Move the rack by hand again to make sure there is no binding, and let go to ensure it snaps back to closed. Move down the line checking as you go, articulating the rack as needed externally till you feel that groove in each metering pump location. All 4 should go in relatively easily.

Just remember after the final check, to move the stop set screw back into position.

 

[BrentN]

If you take the #2 pump out, are you able to move that pump's metering lever back and forth easily? If not, that pump might be seized, which would prevent the fuel rack from moving when that pump is installed.

Or another thought would be to use the dead crank switch to bump the engine over, so you can verify the cam lobe under the #2 pump is in the down position before installing the #2 pump.

Here are pics that show the movement of the metering lever.
View attachment 910910View attachment 910911

Thanks so much for the info!! My injection pumps all rotate pretty easily, especially if the spring is slightly compressed. I did spray all 4 of them with Carb Cleaner. I wasnt able to get back out to it before we took a trip to Southern Cali for thanksgiving. With your post and the next one, I am definitely leaning to #2 is bound up due to the location of the cam lobe. If I rotate it is going to drop in easily and make sure the rack moves easily with each inj pump installed. Sure appreciate everyone's help.
I should have put them all to soak before I left though....drats

 

[87cr250r]

Methanol (Heet at your local auto parts store) can free up stuck plungers and racks on installed injectors. Pour it all over anywhere you think it can access moving parts.