Engine/Transmission (1994 - 1998) big turbo, big injectors, little boost

[LVJUNIOR]

I bought a 98 12v that has some mods (see sig) I am new to the mechanical cummins and am having a hard time finding the power.



THe truck will only smoke a little off the line. It will only hit 24psi of boost tops and usualy be below 20psi. I have had an cummins expert drive it and he descibed it as sickly. We checked fuel pressure and it was at 10psi idle and 20psi wot. I have since changed the fuel filter and overflow valve. I do not know which plate it has in it but was told it was a "pump upgrade kit"

The star wheel is almost all the way forward (towards the radiator)



I am told with the injectors pump mods and turbo it should be rippin asphault. I am lucky if I get a chirp out of the tires under full power in a corner.



Does any one have an idea of what to try next? I used most of my money to buy the truck and am runnin a little tight, so I would like to check cheap or free first

 

[LVJUNIOR]

I seem to have no signature. Hopefully this fixes it

 

[KLockliear]

Who's truck was it? Who did you buy it from?



Did you check the fuel pressure after changing the fuel filter and overflow valve? You want at least 20psi all the time... but check it at idle.



Sounds like the boost line that goes from the manifold to the back of the aneroid housing is either disconnected or leaking (or maybe it has a valet switch that does the same thing). Take a brake line clamp and clamp that line where it's rubber and see if the truck gets worse... if not, you're not getting boost to the aneroid and that's gonna limit the truck to ~150rwhp.

 

[LVJUNIOR]

I bought it from a frend of mine tracey Bullock. he gave me the information on the mods as well.



I do not have a fuel gauge yet. I went to A guy in Pahrump who had one. I need to build one but am a little confused on all of the fittings needed.



I will try the line pinch idea tommorow. I was also wanting to get the timming set but it was a lot of money to spend and maybee not solve the problem

 

[KLockliear]

Auto or manual?

 

[MAleshire]

Your signature doesn't indicate whether you have a stock air box. If you do check the filter. You may need to be getting more air to the turbo. If you can't get the air you need with the stock box, you may need to look at doing something like a BHAF. Also, it's hard to tell what might be going on with the supply side of the fuel system without looking at the fuel pressure while actually driving the truck. You may have a slow air leak on the supply side.



Skip

 

[LVJUNIOR]

the truck is an automatic. .



It does have an "air box' it is an AFE I belive. the sheet metal style with the rubber gasket at the hood

 

[Missouri Mule]

1. the fuel pressure after the filter should be 20 psi mininum, as the rpms go up the pressure should go up to.



2. I could be wrong but I thought on the AFC starwheel was turned toward engine/firewall (clockwise) to increase fueling at low rpms.



3. You need to check the boost line (very thin/small hose) going to the AFC housing does not have hole in it or dissconnected.

 

[LVJUNIOR]

does anyone in vegas have a fuel test gauge and willing to check my pressure. the local shop wants $95 to test my fuel pressure

 

[KLockliear]

J&S Diesel can check it.

 

[LVJUNIOR]

J&s is the one that quoted me $95 to check my fuel pressure. The last guy that put a gauge on it took all of 5min to check it. He just took a bolt out of something, spun a guage in and fired the truck up. $95 seemed a little high for 5min worth of work. I would like to build a test guage but it looks like I need to buy a special bolt for the banjo fitting on the fuel filter.



Since I origionaly posted I have cleaned the prefilter and installed an ATS exhaust mainfold.



KLockliear do you have a shop in town?

 

[KLockliear]

Nope, no shop. Used to work for one, but not anymore. Try to get ahold of Joe Donnelly on here. If he's still in Vegas, I'm sure he'd be willing to try to help you out.

 

[LVJUNIOR]

Thanks for the help. found someone very helpful in Vegas. the fuel pressure is fixed and we found a major boost leak. I also got a good education on the cummins engine while I was there.

 

[KLockliear]

Who'd ya find?

 

[LVJUNIOR]

I am not sure if he want's to be known. He reads this forum and if he want's to come out I will let him. don't mean to be rude just trying to respect his privacy

 

[KLockliear]

No worries. Just figured I'd know who it was.