What symptoms will a bad injection pump show? My truck lost all power the other day while driving home. It starts right up but now misses at idle (sounds like a old tractor, very rough and shaky) and white smokes excessively. The miss sounds like an entire cylinder is down, which makes me believe it is the injection pump.

As of yesterday I have:
adjusted my valves
checked my timing (16.5 degrees)
went back to stock injectors (pop tested)
inspected head gasket (no oil/water mixture or bubbles in radiator)

My O.F.V. is 3 years old, lift pump is 2 years old, pre-filter has been deleted with new gasket, 4K on a fuel filter, and fuel lines were recently replaced. At idle I am getting a steady 20 p.s.i of fuel pressure, when usually i was getting a fluctuating 25-30 (due to a snubber valve being too big).

My truck is a 1994 5spd with 260,000 miles and no major mods. I know these pumps had plunger problems, and before I throw more money at it I would like some suggestions. I just can't see the severe miss being related to a bad O.F.V, or lift pump.

 

Very uncommon for these P pumps to fail.

Check fuel pressure> http://www.cumminsforum.com/forum/94...-12-valve.html

http://dodgeram.info/tsb/1996/14-07-96.htm

 

I'm not going to say you have a bad pump,because you never know until all the tests are complete...

My truck would shut down completely at highway speed.Never happened driving in the city..

On the highway,it would happen sometimes in 100 miles or 10 miles..Complete shutdown...Would wait a minute and it would restart with no problem..Drive for maybe 10 miles or more...and again a complete shutdown..

Did all the tests and couldn't find the problem..Last final thing was to replace the IP...That fixed the problem...Must of been a internal problem...Something was hanging up..

 

I finally got a chance to work on the truck this morning, but my symptoms are still present.

As of today:
-new fuel filter
-pre-filter screen & hose between pump/filter
-new (different O.F.V.)

I also ran my truck off 5 fresh gallons of diesel in a fuel can (because I found a lot of rust and gunk in my pre-filter screen). After running my truck for about 5 minutes it ate up nearly 3 gallons of fuel, then stalled. I now cant get it to start, and I cant get the O.F.V. to release when priming it.

Here is a link to a youtube video of it running. What does it sound like, a bad lift pump (remember 2 yrs old), or a bad injection pump?

http://www.youtube.com/watch?v=1tLiu...PvQ&playnext=1

or do a search on 12 valve bad injection pump?

Thanks in advance!

 

My first instinct would be injectors. I know you said you swapped in freshened stockers. Start cracking lines to kill the cylinder, see which one doesn't change. When you narrow it down to which cylinder isn't firing, swap the injectors from a good cylinder. If the issue moves, its injector related. If it stays, its pump or engine related. Get a compression tester and check the suspect cylinder. Should be up around 400 psi. If that checks out, move back towards the injection pump. The 94-95 trucks did have issues if warping barrels. I would expect it to stick a plunger and thus the rack, but a miss would definitely be a possibility.

Going through 3 gallons in 5 minutes isn't surprising, your fuel tank is much fuller now. Open the bleed screw on the fuel filter discharge banjo bolt and hand prime the lift pump. Once you get fuel there, remove the OFV and keep priming until you get fuel out of the port. Then reinstall the OFV. It should squeal, but it doesn't always. My truck can be primed up without it making a sound.

 

Do you add 2 cycle oil to your fuel? Mine kinda acted the same way until i thought of the poor [none] lubricity of the fuel now days. Been adding 2 cycle oil to every fillup. The government is going to come right out and say they want your engine off the road, so they do it in a different way.

 

Do you add 2 cycle oil to your fuel? Mine kinda acted the same way until i thought of the poor [none] lubricity of the fuel now days. Been adding 2 cycle oil to every fillup. The government isnt going to come right out and say they want your engine off the road, so they do it in a different way.

 

Tate, I just took the AFC housing off and verified the rack is moving, Im going to re-bleed the fuel system and see what happens. I do not have the right tools to check compression, but once running I will re-check the injectors. I will keep posted and I appreciate the replies!

 

Just re-bled the fuel system and the truck is still missing. At first start up I was getting 15 p.s.i, but after bleeding all injector lines it is now staying around 20-21 p.s.i. Every injector is changing the sound of the engine, and I do not know what else to check. I live close to a Bosch injection shop, what type of tests can they run to see if my pump is going bad? How much would they cost?

 

Sounds to me like a dead hole, did you pull the valve covers and make sure all the pushrods are in place and valve clearance is good? Just noticed things you have done, checked valve clearance
Might have to pull injectors and do compression check before condeming injection pump.

 

So I finally had a chance to run a compression check. The numbers were:

1-355
2-360
3-390
4-385
5-0
6-0

As you can see, while cranking it over the last two cylinders wouldnt even register on my gauge.

Would this indicate a leak between cylinder 5 & 6?

 

Hmmm....Maybe time to pull the head...But what till more members give feedback..

Maybe you have a badly blowen headgasket..But just to confirm...Any antifreeze leaking around number 5 and 6?

 

Not sure I ever saw a 0 reading, have seen really low ones though.

Believe I would pull 5 and 6 Valve covers and insure pushrods were still in there, and have someone spin her over while you watched the valve action, not wishing any bad luck on you, but perhaps the Cam broke between 4 and 5?

( only reason I suspect something like that is the 0 reading, no air in, no air out, gives no reading..... even a blown headgasket should show some pressure )

 

Looks like pulling the head is in your future, but make sure your valve train is intact and working before that. Who knows, you may be missing the heads of some valves.

 

Kinda sounds like blown headgasket equalizing pressure between 2 cylinders. Bent pushrods or chiped or broken valves, Broken valve springs, valve tappets? Only cams I have seen broke were regrinds.