RichN

As the title states, I installed my 4kGSK along with 60# springs today. My truck will not rev past 3000 either reving it freely in neutral or on the road under load. When it gets to 3k, the motor starts to pop and falls on its face. I only see at max 25PSI of boost. The truck has a TST #5 plate in the stock position with the boost elbow installed, 15.5 degrees of timing, 4 inch exhaust and bhaf.

What causes this? Lack of fuel?

Thanks

Tate

Check your fuel pressure. Sounds like you are running out on the top end.

West Coast

You injection pump and DV"s are most likely the culprit. My 94 did the same thing. The 94-95 pumps just don't do well with the 4k spring kit. Even DV's did not help me with more RPM"s....

RichN

What kind of fuel pressure should I be having?


Westcoast, did you replace your injection pump in your 94?

Tate

Around 25psi at idle, and 35ish at 2k rpm with no load is the specs. If you can get a gauge you can run into the cab and see what it is under load as well, since thats when it matters.

rebal

I bet the springs are 1 click to tight, I just did one and it will tag 4k _ right now

West Coast

Rich my injection pump had been rebuilt and timed at 15 degrees. I had messed with the clicks on the GSK kit and nothing helped. Talked with Piers Diesel and they also mentioned that a 94's and some 95 injection pumps will not support fuel up to 4k even with DV's.... Several other people on this forum have had the same issues with the 94 pumps....

RichN

The original springs were two clicks, so that is what I set the new ones at. Truck starts right up, idle is only about 50 rpms higher than before. Everything there seems ok.

RichN

The guy that did my timing, said my pump was "ancient", had a cpl # of 1550, which makes some sense since this truck came from the factory with an HC1 turbo instead of the HX35 like 95 and up models are supposed to have.

I did get a new overflow valve, and pre-filter screen since I have no idea when they were last changed. I need to pick up my needle valve from Grainger, and tap the banjo bolt to check the fuel pressure. I'll do these on the weekend and hope for the best.

Thanks for your help.

Brendan

The 160 pumps will only fuel until 3200 rpm, that's just there limit.

RichN

The truck has a 175 pump in it according to the tag.

rebal

50 rpm higher ...I have installed many gsk and if it goes in the same way it came out your RPMs should be the same at least I have not had to readjust the ones i did