fuel pressure problem?

[lgonzalez_1986]

ok you guys here we go again, i have a stock gn getting only 20psi, i already replaced fuel filter, fuel pump from ac delco, adjustable fuel regulator from accufab, so i dont know what the problem is, i have 42.5 lbs inj. with an old pitbull chip to match, any ideas?

 

[RegalT-type85]

Is that chip made for those injectors? Did you set the Fuel pressure regulator right?
I'm sure it's not running right, when did you notice this change, after a install of some sort? recently/just happened?

Delco pump?? is that stock 190lph, you might have a lower LPH pump then stock.

I'm gonna say the Adj regulator is set low.
Did you try adjusting it higher?

 

[RegalT-type85]

misread your "to match" on the chip sorry thought you meant it as, you have a pitbull chip "also" match.

 

[lgonzalez_1986]

yes the chip is for a 42.5 inj from 96', i bought the car and the fuel pump was out, then i went to kohweiss got an ac delco fuel pump and got a new filter and still nothing i adjusted the regulator all the way and it just went up to 20psi it had a kenne bell regulator then, i replaced with the accufab and still no results, then i thought it was the gauge since it has inline fuel gauge on the fuel rail, so my dad tapped his gauge at the end it had the same reading , so i dont know what else it can be any suggestions, im gonna replace the ecm and go with turbo tweak chip.

 

[bmackinnon]

yes the chip is for a 42.5 inj from 96', i bought the car and the fuel pump was out, then i went to kohweiss got an ac delco fuel pump and got a new filter and still nothing i adjusted the regulator all the way and it just went up to 20psi it had a kenne bell regulator then, i replaced with the accufab and still no results, then i thought it was the gauge since it has inline fuel gauge on the fuel rail, so my dad tapped his gauge at the end it had the same reading , so i dont know what else it can be any suggestions, im gonna replace the ecm and go with turbo tweak chip.

ecm and chip have absolutely nothing to do with fuel pressure, so you are wasting your time there... sounds like you have a restriction or kink somewhere in the line, or perhaps the rubber hose in the tank from the fuel pump to the pump hanger has gone soft and split/is leaking, resulting in a loss of pressure from the pump to the rest of the fuel system..... which is fairly common.... did you replace that hose/pulsator assembly when you replaced the pump?

 

[lgonzalez_1986]

yeasl wit a hose from goodyear! how do i check for kinks?

 

[bmackinnon]

I would do a visual check of every inch of the fuel line first.... drop the tank down some and see if you may have bent/kinked the metal line at the top of the tank during the tank re-install?... maybe a hose clamp positioned wrong has bent something? if all looks good, I would clamp a gage right to a hose at the tank exit, fire the pump up, and check the pressure there .... if it is only 20 psi there, either the pump is crap, or the line from pump to hanger is leaking... the pump should make 80+ psi deadheaded at the tank exit... only run it for a short burst like that though... fwiw, why did you not get an upgraded pump (walbro 340) when you changed it? who the hell is kohweiss? I'm wondering if you got the wrong pump.... some of the ac delco pumps for cars of that era only put out 20-ish psi.... like my old carbureted '87 firebird... in-tank elect. pump supplied traditional block mounted mech. pump.... hmmmm...

 

[Chuck Leeper]

N/A pumps, [for TBI], run in the 15-20psi range...

 

[lgonzalez_1986]

kohlweiss is our performance shop out in the bay in cali, i didnt go wit an upgraded pump at the time because i was new to the turbo buicks no everybody tells me i should of gone with a warlboro, i would do that check my fuel line and do i need a special gauge to check the pressure at fuel pump

 

[Red Regal T]

They might have given you the wrong pump. Most speed shops are oblivious to turbo buicks. They think the world revolves around Chevrolet.

 

[RegalT-type85]

I agree with both above, fuel pump might be wrong, got a part # ?

 

[lgonzalez_1986]

think ac delco 642

 

[Red Regal T]

I couldn't find any fuel pumps under that number but I did find this one ...

ACDELCO US Electric Fuel Pump,EP242 - oehq.com

That would be the correct pump if that's the one you received, but apparently, it's not working right.

 

[lgonzalez_1986]

yeah its that one is that the right one? 242 thats the one i have

 

[Red Regal T]

Well, you just need to be sure you have no restriction, and if you don't, that pump is defective. Order a Walbro pump from GBodyParts.[/url]

GBodyParts.com Online

 

[bmackinnon]

Well, you just need to be sure you have no restriction, and if you don't, that pump is defective. Order a Walbro pump from GBodyParts.[/url]

GBodyParts.com Online

Agreed... but if a new pump is in order, I would go with the GSS340 pump from Racetronix if it were me... probably same price or real close... and get the fuel pump hotwire kit also... and for god sakes, put the vac line on the regulator all the way, and clamp or ziptie it on both ends!!! Don't want that coming off!!!!, and fix that coupler on the throttle body! That sure as hell ain't gonna hold....

 

[TurboDave]

Let me ask the obvious missed question.... When you're observing your fuel pressure, is it with the engine idling, or just with key on, engine off?????

 

[Red Regal T]

Agreed... but if a new pump is in order, I would go with the GSS340 pump from Racetronix if it were me... probably same price or real close... and get the fuel pump hotwire kit also... and for god sakes, put the vac line on the regulator all the way, and clamp or ziptie it on both ends!!! Don't want that coming off!!!!, and fix that coupler on the throttle body! That sure as hell ain't gonna hold....

but .. but .. :biggrin:

The old GSS340M was a GSS340 (Mustang pump) that was machined down (that is where the M comes from) Walbro found it was not cost effective to continue to machine the pumps and made a new bottom with the correct opening for GM cars. For a better fit and installation.

 

[lgonzalez_1986]

yes turbo dave, i do turn the car on and let it idle for about 10 minutes i dont want to run it any longer than that,