Injection pump timing

[tim curran]

With 75 horse injectors upgraded turbo 4 inch exhaust 3200 spring performance fuel pin, my pump is maxed can't turn it up anymore, I just put my pump back together and put the timing all the way to the head. Truck runs ok but motor has a different tune to it. I know I just increased the timing. What is the best result for moving the pump, can it be to far?

[cougar]

Yes, it could be. The problem with timing is there are too many variables. Best approach is small increments until you find that happy spot for your particular set up. Just remember that when you change one thing it will effect another.

[RCCUMMINS89]

With DDP "75hp" injectors.... to the head MAY be too much. I would personally start with about a 1/4" bump and go from there.


How I tune my pump (keep in mind every one has different expectations of how their truck should drive).

I advance the timing until I notice that I don't like my low end anymore and it feels like I lost power until I'm at wot. At that point I retard it a tiny bit. That usually gets me pretty close to a good all around. Other thing I do (because I have big injectors) is advance it until it is clean at a idle.

[tim curran]

My low end is good I think my wot isn't as good as it used to be. She is a bit hazy at an idle and don't smoke like a freight grain st wfo.

[RCCUMMINS89]

Well.... your injectors are a marine angle, so I could see that it is hazier at idle. Not smoking like a freight train at wot is a good thing, it means you are burning more fuel. Or did I mis read that?

[cougar]

Maybe time for a bigger lift pump.

[DMan1198]

Mine always cleared up with the ddp3's even with stock timing. The worst I got was a light haze at WOT during summer after I added a pin. Mine did feel like it layer down a bit in the top end. Added an electric lift pump and it pulled harder in the top end

[tim curran]

I have a ten psi electric pump to go with the mech. Lift pump. I just did a new head gasket I pit it back to stock thickness. I was running a .020 head gasket to allow more room for boost.

[JimmieD]

I don't think you want to run an electric lift pump in combination with a mechanical lift pump. If the mechanical can't keep up then the electric can't pull through it and if the electical can't keep up then the mechanical can't push through it. If you run electric first then mechanical, the mechanical will block any advantage from the electric. If you run mechanical first then electric the electric can only pump as much as mechanical can deliver to it.

Either/or proposition.

[tim curran]

I put another spin on fuel filter on the frame rail so I figured the electric pump would push the fuel to the mech. Lift pump so that one would not have to work so hard it would never starve for fuel.

[RCCUMMINS89]

If I'm understanding correctly...........You feel you've lost top end power AFTER you advanced your timing, correct?

Or were other things done at the same time?

[JimmieD]

If the original lift pump is a diaphragm type I believe it's possible for added the electric pump to blow out the diaphragm and cause failure. The guys here might know better or know otherwise, but that's what I'm thinkin...

If so it's possible you could test by bypassing the mechanical diaphragm pump and just run the electric to see what happens?

[tim curran]

I lost power but I also took out my worn out Denny t fuel pin and pit back the one from Ind. Inj. Its not as good as the Denny t one. I figure the electric pump would just keep a constant fuel pressure to the diaphragm pump. I don't trust electrical pumps to run one alone. I have had to replace way to many electrical pumps in my day to have my mechanical diesel be crippled By a. Electrical fuel pump when it dies.

[DMan1198]

I tried that electric into diaphragm setup. It totally killed the mechanical pump, and started pulling air. Now the truck is just sitting until I get the rest of the parts to build the engine

[JimmieD]

Thanks, DMan, that's exactly what i was talking about!

Honestly, Tim, you're not helping yourself one bit by running them both, just a bigger chance for failure.