m1008 surging. bad injection pump??

[84cucv1ton]

this is what im working on now. got it from south NJ. missing some thing. put them on. was told the pump is bad.. turned the key just for the heck of it. started right up. i was thinking the pump is ok. then it surges. pump on the way out???

thanks for the help here some pics. since you all like pics

 

[acmunro]

Could be several things. The first thing I would check is the Injector Pump Return Line check valve. It will surge if someone knocked the ball out to run it with a bad IP. Only takes a minute to check. If not that maybe a fuel dellivery problem to the IP.

 

[84cucv1ton]

where is the Pump Return Line check valve? didnt know there was one thanks

 

[acmunro]

The IP return check valve is screwed into the top of the injector pump it has a rubber hose attached. Remove the rubber hose unscrew the valve it may be plugged or it may have had the ball punched out. The ball is clear so you may have to carefully insert some object to see if it is still there. It should move slightly and is spring loaded. Sometimes the ball is removed when the injector pump is failing to prevent it from becoming plugged with debris and causing a no run situation. If the ball has been removed the engine will surge - timing issue .This failure is mainly a 1985 and older model problem.

 

[gaunt1969]

does it surg only at idle? and does it come up to speed?.
acmunro suggestion is the most likely cause for it to surge at idle

 

[acmunro]

I just replaced an injector pump with the problem I described yesterday. It surged at idle and ran down the road about like an old Holly double pumper with a bad power valve. At steady throttle it would surge. With the replacement Injector Pump in runs real nice.

 

[84cucv1ton]

surges a lot at idle. not as much when i hold the gas down. still does tho. thanks i will check this out

 

[T_F_E]

It still could be a fuel delivery problem though, start cheap and work your way from there.

 

[Wolf.Dose]

It might help just to change the top cover with its internal parts. These parts tend to work inpropper if the fuel was contaminated with water, so they rust.
Are your electrical connections good? Sometimes they are not very tight and tend to temporarily fail.
Wolf

 

[2deuce]

My CUCV has given me surging problems if I park it nose up high and don't start it for a few weeks. Somehow some air gets in the lines. I had that problem yesterday, it wouldn't start. I rolled it down to the flat, let it sit for 24 hrs and it started tonight, but with alot of surging for about a minute until I believe it clears the air out. I'll start it again tomorrow to see if its back to normal.

 

[acmunro]

T_F_E spending about 5 mins on checking a return check valve is about as cheap as it gets. Gives you a pretty good indication of pump health- if it is clogged with black or brown debris its probably time for a new IP. If the ball is knocked out chances are it was clogging and Previous owner knocked it out. A good check if the ball is missing is install a cheapie clear fuel filter between the check valve and the metal return line. Drive truck around if the clear fuel filter starts to fill up with debris and your Main inlet fuel filter (on fire wall) is known to be good and not letting dirt past, Your injector pump is most likely failing. This test should to some degree rule out the Previous owners statement from the initial post that the IP is bad. I am not saying this is the problem just where I would start since the previous owner said the injector pump was bad.

 

[84cucv1ton]

ok thanks, hope you made out well with the trucks you got from us.

 

[acmunro]

Your welcome

 

[84cucv1ton]

finally got there and did this. ball is there. on the passenger side of the pump down near the bottom the shaft is leaking. so now i know time for a new pump thanks guys

 

[CUCV85]

finally got there and did this. ball is there. on the passenger side of the pump down near the bottom the shaft is leaking. so now i know time for a new pump thanks guys

They all start to leak at the throttle shaft. I put 2 new o rings on there even though the old ones APPEARED fine after I took the top apart. Well, it ran for a couple more months then total pump failure. I ended up having the IP rebuilt. You could try to fix the leak with new o rings, the work to get them out is intensive - you have to remove the intake to pull the throttle shaft out of the Injection Pump. So, will you at that point just remove the IP and have it rebuilt your call. If you are going to KEEP it for some time then by all means get it rebuilt. These trucks are 25 years old OLD I said. Having the pump rebuilt is the best thing you can do for your truck. Change all fluids and filters is next.. HAVE FUN - Be Safe

 

[mkcoen]

I'm having a surging problem with my M1010. My problem is not at idle but when under throttle and you let off the accelerator. Acts like it is about to die and then, boom, huge surge. I did check and the glass ball is missing. Is it possible to just get the check valve and replace it?

 

[acmunro]

If the ball is missing the injector pump was probably failing and someone removed it. I would change the check valve and see or just install a clear fuel filter in the return line right there and see if it fills up with debris. I need to replace the pump on my one M1010 also for the same reason. Timing is eratic with the ball missing.

 

[mkcoen]

Will adding the fuel filter help the surging or just tell you if it's getting junk in it? Is the check valve readily available or something that's going to be difficult to come up with? Since my engine only has 28k miles not sure why the IP would be going out that soon. I know anything can happen but just seems a little premature.

 

[Keith_J]

30. STALLS UNDER DECELERATION OR HEAVY BRAKING
Step 1. Check idle speed, (See TM 9-2320-289-20)
Step 2. Remove governor Cover-. (See paragraph 3-3 Check for black particles,
If black particles are evident, replace governor weight retaining ring. (See
paragraph 3-42)
Step 3. Remove governor cover. (See paragraph 3-3 Operate throttle shaft and observe
governor assembly and metering valve for binding.
If there is binding, remove governor assembly and metering valve. (See
paragraph 3-39) Replace any damaged components. Clean metering valve
with calibration fluid. (Item 13, Appendix B) Reinstall governor assembly and
metering valve. If binding continues, replace metering valve.

Just as I suspected! Yes, when we have time, about a day...in the mean time, print out the relevant sections in the -34 referenced above. Also, troubleshooting sections pages 2-43 to 2-45 for the charging system.

What happened to the IP? Being stored for a time, diesel can harden to a varnish. This can cause sticking of the internals, all wetted by diesel. And using alternative fuels like waste vegetable oils? Horror. Yet one member here claims I was slinging fear, uncertainty and doubt when warning about using alternative fuels!

Sorry, sometimes I find a soap box and start preaching. Not that you need it!

 

[acmunro]

The cheapie clear filter would show the retaining ring failure. It wouldn't help anything except keeping the debris out of your clean fuel tank. You could also remove the top of the IP and look.

Why did the IP fail with such low mileage ? The truck is probably a 1985 or older model. 1986 and later models have Injector pumps manufactured with improved materials to deal
with this problem.
Some people blame Jet A fuel or other additives used by the Military.

I have a 1985 M1010 and a 1984 M1009 that had this problem. Good luck.