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-   1st Generation S-series (1983-1994) Tech (https://blazerforum.com/forum/1st-generation-s-series-1983-1994-tech-40/)
-   -   94 CPI vortec fuel pressure question (https://blazerforum.com/forum/1st-generation-s-series-1983-1994-tech-40/94-cpi-vortec-fuel-pressure-question-74733/)

bam_9_9_9 10-28-2012 11:26 PM

60psi when its running.

AndrewO1991 10-29-2012 05:13 AM

Boosted it up to 60psi when the pump is on. Alot of driveability issues are gone. It used to hesitate before a shift, now it doesnt. And the bogging is gone. It still leaks down to 50ish quickly and once again no visable leaks under the plenum so im thinking a fuel pump is in the future.

bam_9_9_9 10-29-2012 09:30 PM

thats good to hear. im glad i could help. if you ever have to replace the pump and you only replace the pump instead of a whole new sending unit, then make sure you also buy 3in of 3/8 gas line. it goes from the pump to the sending unit. they usually get pin holes in them and leak. but if your holding a steady pressure at 60psi then it should be fine.

AndrewO1991 11-01-2012 10:17 AM

The thing is it doesnt hold at 60psi. Immediatly after the pump shuts off it drops to 50psi then drops only 5-10 over an hour.

1sttimejimmyowner 11-01-2012 11:56 AM

Sorry I cant help with your fuel pressure problem but as far as the mis goes it could be a number of things other than an injector.You may ave carbon built up inside your distributor cap/rotor on the electrical contacts.EIther replace or sand all the corrosion off with some light grade sand paper.Seems to be a common issue on my truck anyways.Check your plugs and clean then regap them.Check your sparkplug wires as well.This could be a salution to your bogging down problem.One other thing did you check the openings at the end of poppets they could be plugged up,this would cause a miss and lack of power.Best of luck hope this helps.

AndrewO1991 11-01-2012 03:58 PM

I guess i didnt say that after turning it up to 62psi it doesnt bog anymore. Also the whole ignition system is new, even the distributor. The old one had some worn out gears and let the timing just around. It runs good for the most part, I think I still need a new fuel pump. Pressure still drops and there isnt a leak under the intake.

bam_9_9_9 11-02-2012 09:09 PM

yea thats fine if it drops to 50psi when key off and holds. if it only drops 5/10psi over and hour then thats great. no problem in the fuel system. its all good.

AndrewO1991 11-06-2012 07:44 AM

So, here is an update after i adjusted the fuel pressure to 60psi. The needle isnt erratic like this when the truck is cold, only after it has run for a while. When cold it's similar to the first vid only it hovers at 60psi instead of 55. I only decided to test this becasue after its warm the idle is unstable, it will drop real low, then go back up, and so on. It can level out every now and then but if you snap the pedal for a second it almost dies then saves itself, then tries to die and so on. It's like it doesnt know where to idle.

bam_9_9_9 11-07-2012 08:41 PM

i would change the fuel filter next and see what happens. ive seen pumps die because of a clogged fuel filter. happened to my bravada. pump went out and put a new one in and ran like crap poor idle and highway driving was really bad. changed the filter and now no problem for over 2 years.

with a clogged filter the pump works overtime that might explain the eratic pressure and bogging down. my 97 bravada did the same thing with a clogged filter.

AndrewO1991 11-08-2012 07:15 AM

Sadly Ive already replaced the fuel filter and the old one seemed ok. I've been reading about people having similar idle issues with the egr being plugged, i think im gonna start there. Its one of the few things i havent checked out. Vacuum is around 16, mayne a tad low but didnt seem that low. Im also wondering about the cat, when the rpms drop low like it wants to die the exhaust sounds funny, and when it catches itself and revs up the exhaust is really hot, i know its normally hot but i mean its burn your hand if your to close hot. Last time i experianced that was with a clogged cat. But that car wouldnt exceed 2500 rpm, mine drives fine. Stomp the gas the thing flys. Its important to know the rpms never seem to go much higher than normal, it just dips down like it wants to die.


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