merr6267

Hey Guys,
I started a thread a while back about a possible blown head gasket . . . I was having a miss on 4 and 5 cylinders and was getting fuel at each injector. I swapped injectors 4-1 and the problem stayed at #4. I figured that I was having a compression leak between 4 and 5 so I just pulled the head. The truck was new to me and I was kind of expecting a blown HG anyway after running it up to 60 psi when it wasn't fully warm. I wanted to see how all the holes looked anyway.

Well it wasn't a bad head gasket, and all the cylinders look good. I finally got it all buttoned back up today and bled the heck out of all the lines. The 4 and 5 cylinders still have a miss, but I noticed that there is not a good spray of fuel coming out of those lines when I crack them open. All other cylinders blast the fuel upward when I crack the lines open. 4 just kind of dribbles the fuel and 5 is marginally better.

I ran it for a little with the exhaust manifold off (I know it's not good to do but this is for testing) and could see that 5 would fire when I revved it up a little. 4 remained dead. I'm pretty sure that it's a IP problem, but could it be as simple as a stuck delivery valve? It seems I've read about that, but I have not been able to dig anything up to answer my question.

I've also read about a stuck plunger too . . . but I hope it's not that, I'd hate to have to send the pump in . . .

So, if I can expect to take off the delivery valve holders, where is a good place to get the socket? The guy at Cummins said he stopped stocking them, and they were over $100 anyway . . . I think I read that Scheid had them or something.

What do ya'll think. Am I going to need to pull the pump? Do you think it could be a big air pocket within the pump? I tried to bleed the fuel out by hand pumping the Lift Pump and opening the overflow valve, all air bubbles stopped there too. I'm hoping that it's just a delivery valve problem, but what would cause it. It all happened right after a little spirited driving.

Thanks in advance,
Phill

Crimedog

To me it sounds very possible that, as you say, either a delivery valve or plunger could be the culprit. Especially considering you swapped injectors and it made no difference in the performance. You can get the delivery valve socket from Piers or Snap-on. I think it is cheaper to get it through Snap-on, around $40 if I remember right. It may be worth it to take the lines off and inspect the delivery valves just incase it is something simple, I think there is a spring in contact with the delivery valve... I'm definitely no P7100 expert, but to me it sounds like it is inside the pump.

jughead

my 97 has a 50 lb. drop on #5 and it misses at idle. none of my cylinders go over 300 lbs. though. didnt get the engine i thought i bought i guess.

JKM

Sounds like a definite IP problem , I Doubt it is a DV problem, they would have to be stuck open... Sounds like maybe a plunger got scratched somehow... , if it was a stuck plunger ,you wouldn't be able to shut the truck off, or rev it up.

merr6267

Hey all,
I seem to have it figured out now.
I got antsy, and took a vice-grips to the DV holders, used a rag around the jaws to protect the splines . . .
Anyway, I took out the DV on cylinder #4 and the piece that goes around it and saw a little sealing washer on the bottom. I'm pretty sure it's a sealing washer anyway. I couldn't see for sure on the exploded diagram exactly what it was, and my pump had been modded by a shop a while back anyway.
Well, the washer was bent on one side like it had been pinched. I looked at the one in a good cylinder and it had the same deal, but wasn't pushed out like #4. I pulled the washers out of 4 and 5 and noticed that they were a little large for the holes that they fit into.

I straightened them out using a brass punch on an aluminum plate. They were not perfect, but better than what they were initially. They didn't fit into the holes well so I bent them slightly to get them to the bottom. I'm guessing that that was the problem at first. Maybe it was all well sealed when it left the pump shop but the washer got pushed out when I was rodding on it one time. I screwd it back together and all 6 holes fired. Yeay!

I think it was as simple as the sealing washer getting pushed out under hard fueling which led it to bleed pressure off and not deliver fuel.

Now I'm just getting it all buttoned back up and going for a light drive to get some heat in the motor so I can torque the head again. I'd hate to have to replace the HG again . . .

I'll have to talk around a little and see where I can get the proper washer for those things and take all the DV's out and re-seal them. I'd hate to have one of my rigged ones push out again.

I'm happy I got to the bottom if it finally, but kind of upset that I ended up pulling the head for no real reason. (well, I did port it a little more)

Take care,
Phill

infidel

Had someone been into the IP before you?
I didn't think the washers were required except in the smaller '94-'95 pumps.
That could be the whole problem.

merr6267

Yeah, the PO built the truck, and he had a shop build the pump. They balanced it and all that stuff . . . I had read about the early pumps having washers and the later ones not . . . I've never had a pump apart to know the difference.\

I wasn't sure if that was 'the' DV washer everyone talks about or if that is another piece that never gets talked about. Maybe I can just pull 'em out . . . but I think I'll look into it a little more.

Oh, I used your gallery for the diagrams and pics . . . thanks

Thanks,
Phill

TheBigNasty

If you have Piers dv's they don't need the washers. Mine were in there and mangled like you said. Took em out, had to use a hook to get some, and idles great.

merr6267

Hmm, If I have any other trouble I'll give it a try. All seems well now . . . but you never know what might happen after I get my o-rings seated into the gasket and I lay into it again.

Can't friggin' wait. Gotta re-torque again tomorrow morning, and then again, and probably again.