De-Fueling issue..

T

TheKid

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Apr 2, 2012
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Quick run down , ive got a 94' 12v , with 4k springs , no fuel plate and some other pump mods , exaust and intake. now , it feels like it runs out of fuel.
i think this because from a standing start it run great to about 2600rpm+ then noses over and looses boost and smoke turns white. yet if im on the freeway at say 65-70mph turning 1600rpm i can put my foot in it and it wont hit 2k befor it again noses over. i changed the lift pump and it got better , didnt fix it but did get better. ive got a rack plug coming as well as a OFV , ive been told those could be a contributing issue. ive also thought maybe duel feed lines into the pump could help or maybe even a plugged vent in the fuel tank??? im new to the diesel thing so any help would be great!!
 
i forgot to add that the truck did the same thing befoor i did anything to it , only differance is now it runs out of fuel ALOT faster.
 
What is your timing set at?

Did you adjust the high idle screw all the way in after installing the 4k kit?

What is your fuel pressure at the inlet of the injection pump?

Is your shut-off solenoid adjusted correctly?
 
timing is stock , seting it next week i hope.

nope didnt have to adjust it idled fine.

no fuel pressure gauge yet , still need one

and i dont know how to check the shut off.


ive read every single thread on here and non of them sound like what my trucks doing. it run great untel the smoke goes white , no miss or rough idle , shifts great no white smoke unless i flat foot it. coolant leval is fine , all the hoses look to be fine. it seems that if the timing has slipped it would do it alot more? i havent been driving it alot because i dont wana hurt nothing untel i fix it
 
i would have to agree based off of pretty much nothing over then what ive read on here. and because the timing is all i havnt done yet. ive heard the the stock lift pump is good for 600+ hp and im not near that right now so that should leave just timeing , id think. what else could cause low fuel pressure? please dont say IP , ill cry.
 
Clogged filter, bad ofv, kinked line, junk in the tank, or the injection pump. You need to get a gauge on there and find out what your fuel pressure is. Lack of fuel can starve the pump and hurt it.
 
TheKid said:
timing is stock , seting it next week i hope.

nope didnt have to adjust it idled fine.

no fuel pressure gauge yet , still need one

and i dont know how to check the shut off.


ive read every single thread on here and non of them sound like what my trucks doing. it run great untel the smoke goes white , no miss or rough idle , shifts great no white smoke unless i flat foot it. coolant leval is fine , all the hoses look to be fine. it seems that if the timing has slipped it would do it alot more? i havent been driving it alot because i dont wana hurt nothing untel i fix it
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Stock timing isn't going to pull hard beyond about 2500, you need to bump it up to 16* minimum if you want it to pull hard to 3000ish rpm.

HIGH idle screw...not low idle screw. If you haven't adjusted it for full throttle travel you won't ever get more than 3000rpm out of it.

Knowing fuel pressure being supplied is instrumental in tuning these mechanical pumps. Make it a priority to get a gauge on it as soon as possible.

Like others have said, it sounds like a combination of low timing and lack of fuel pressure.
 
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rev it up in nuetral to redline see if it cuts out or smokes gray/white thats the easy way to see if timing is really low white smoke is unburnt fuel typically timing
 
On a 94' with a stock mechanical lift pump, you don't have enough fuel pressure for high RPM. The white smoke is poorly delivered fuel half burning on the way out the exhaust system because the injection pump is sucking a little air combined with low stock timing.

There are fuel delivery issues related to low fuel pressure that are difficult to pinpoint until you add a full-time fuel pressure gauge and an axillary fuel pump on a toggle switch that can be shut on/off for testing purposes.

In a nutshell, 1.5 years of research on my race truck: the higher the fuel pressure, the better it will run. Believe it or not, I'm still seeing performance gains going from 65 psi lift pump pressure to 85 psi. Common thought a few years back was that 40 psi was sufficient for maximum fuel delivery performance. At 40 psi lift pump pressure, my truck is down about 100 whp.

Since your new stock pump and overflow valve setup is capable of just 25-30 psi fuel pressure, I wouldn't expect it to run well above 2500 rpm period.
 
In this burnout video, right at 29 seconds, I turned on the 3rd lift pump system that pushes fuel pressure up to 85 psi and dual feeds the front port of the injection pump. You can hear the increased rpm about 4200-4250 and slight change in engine tone. On the drag strip the 2nd pump pushes the system to 65 psi and gains a little over 80 HP, the 3rd pump pushes the system to 85 psi and is not as large of gain but still worth about 20 HP on top of 2nd pump's gain.



[ame="http://www.youtube.com/watch?v=TxTtI5oy4hw"]http://www.youtube.com/watch?v=TxTtI5oy4hw[/ame]
 
I think high supply pressure is needed to keep the plungers on the cam at higher rpm. To battle plunger float.
 
this place is better the google. thanks guys , ill get a fuel pressure gauge coming so i can get a reading as well as set the timing , when i did the pump i changed the filter as well. ofv should be here today or tomorrow. i do plan do make a little power with the truck so an electric lift pump prob wouldnt be a bad idea.. with what ive got where would be a good setinf for timing? ive been told no more then 18* no less then 16*.
i need to get the truck running healthy before i go spendin money on maken it faster

X2 on the high idle , how do i go about that?
 
where would yall say is the best place to put the sensor for fuel pressure???
 
kalder said:
I think high supply pressure is needed to keep the plungers on the cam at higher rpm. To battle plunger float.
Click to expand...

The springs are what keep the tappets from floating. High inlet pressure compensates for poor cam style (especially the 160/175hp D-shape profile). The increase in pressure somewhat diminishes the effects of minimal fill time, but still isn't comparable to a better cam being used.

mopar or no car said:
Young gun, can you elaborate on adjusting the high idle screw?

Jordan
Click to expand...

TheKid said:
X2 on the high idle , how do i go about that?
Click to expand...

The high idle screw limits the travel of the throttle lever on the pump, if not adjusted in until it bottoms in the housing, you're not getting all you can out of your GSK no matter how it is set up. The 10mm lock nut will probably have either a metal tamper proof cover or a plastic cover that needs to be removed to access the lock nut. If the metal one is on your pump, remove the throttle lever from the throttle shaft, use a flathead screwdriver to remove the screw that holds the tamper-proof cover on, then proceed to run the high idle screw in all the way.

Here is a picture for reference:
466govspringplugedit.jpg
 
i would assume its the one with the red circle? i will have to do that to. so it sounds like i have a mixture of issues here. 100 small things that add up to one problem
 
I don't believe I have ever adjusted that screw in my pump.... This may be why I need my gov springs to be retarded tight to make it run the way I want.
 
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