Engine/Transmission (1994 - 1998) 12v low on power cant figure it out

[NFoster]

Hello all I hope some one can give me some insight on what to do to my truck. I have a 1990 chevy crewcab with a 97 cummins swap and I am having problem getting it to perform the way I want. I have checked lift pump and adjusted psi 40psi at idle and 30ish at wot and tuned on pump but no major improvement. I even went as far as to removing the plate all together and still wont preform the way It should. Here is a list of what I have . Rebuilt 97 engine with pdr stg2 camshaft balanced and blueprinted with around 10k miles before bombing. Recent hg retorque and valve adjust for safety 215hp injectors and what I belive to be a 911 pump will have to double check and make sure of that. The timing is set at 16deg with 181dv no plate afc ff star wheel ff has an hx35w only getting 30-35psi max with wg blocked. egts will slowly climb will reach about 1300 on a long hill pull in 5th wot. Little to know smoke at wot just a haze very little on takeoff even when lugged. I thing I have a bad ppump have a 913 sitting on bench for another project but dont want to change it out back and fourth if I dont have to. What about the turbo it has a little side to side play but nothing unusual. The truck just wont getup and go like it should my dads 98 and friends 96 both with no8 plates will run circles around me and still have power to push up the hills. Just hope someone can give me some insight as to what to do. Thanks for any and all help... .



Thanks Nathan

 

[Signal73]

to rule out the afc not working make a block off plate to take that out of the mix. you can have a blown diaphragm (i hate when that happens:-laf) inside the afc or a hole in the line going to the afc.

 

[NFoster]

A will do it today if I get a chance the shop is really busy. I will let you know what happens.

 

[kenny61]

my 96 had a leaky wastegate diagphram. leak came on so slow i didnt really notice it till i drove my buddies truck and his was a lot quicker. cheked mine to see what was wrong and bingo the leak was preventing the boost from making it to the afc

 

[Hammer]

I know you say you have the wastegate "blocked",but,are you sure that it was closed when you did that?. I have seen many older 12v's freeze the gate open and then be way down on power just as you described... ... . Andy

 

[NFoster]

Ok well I changed the afc and line after removing them and checking for leaks went for a drive and no diff. I also have checked the wg and yes it is seated tightly and is unhooked from the boost line completely. Have checked for boost leaks and didnt find any. I went for a drive to day and ran it hard to see what it would do and now I have a miss. . I checked all of the exhaust ports with a heat gun and two cylinder 1 and 5 are about 20-30deg cooler then the others. What about running a ppump low on fuel pressure will that hurt it like the vp44 I know this pump was ran low on fuel pressure for a while before I got it on had like 15 at idle and would fall to almost zero under wot. Just a thought I think my pump is gone so going to change it this weekend and see what happens dont thing two injectors will go bad in a matter of a few miles. Anyway what do you guys think does this make any since or is every or does this sound like a pump problem.



Thanks for all the help and advice will keep everyone posted





Nathan

 

[TwinTurboDave]

this may sound dumb, but when was the last time u changed the fuel filter. . Seems to me like u have a clogged fuel filter

 

[NFoster]

Just changed it whan the problem started 10-15 miles ago and the old filter looked good.

 

[Dewjr]

you might want to e-mail Joe G. and get his write up on fuel systems.....

 

[MMcCallie]

My truck was doggy for several months. The power came on suddenly one day and stayed. Night and day difference, extremely drastic. Later discovered that the throttle linkage was loose. Perhaps something in the linkage down there was misadjusted. Laser Bob helped me tighten it up and set the idle. Lost a little bit of power.

Had to adjust the idle again a few weeks ago and the power is gone again. With my new turbo, an HTT62/12 I am making decent boost, 44. 6 my record but with a light haze. I'm going to try readjusting the throttle linkage again when I find time. hopefully you'll have solved your problem by then but what you are describing sounds very familiar.
-Matt

 

[tgordon]

I also have checked the wg and yes it is seated tightly and is unhooked from the boost line completely.

this may sound stupid, but you did plug the line? I am suspecting your trouble is 100% fuel, how is your overflow valve? I belive tha little banjo fitting toward the front of th epump on the side by the block. Holds the pump return line to the pump.

 

[Lightman]

Check and see if your shut down solenoid is pulling the lever all the way up or is adjusted to pull it all the way up that can cause low power. Also your WOT fuel pressure is low for a P Pump it should be 26 or higher.

 

[NFoster]

I worked on the truck last night and found that #3 cyl was dead? I pulled the injectors and pop tested them and checked the spray pattern and all looked good all popped around 3100psi. I checked the fuel lines and found no restrictions so i pulled the pump it is a 911 pump and couldn't see anything wrong on the bench didnt got to deep just looked things over. So now I'm going to install my 913 and see what happens I know it's a good pump drove the truck. Will keep everyone informed as to what happens next.



Thanks Nathan

 

[NFoster]

Ok it fixed changed the pump and what a difference. This thing will fly had to be something going wrong in the old pump may get into it and see what was or is going on.