Last year I ran at 50psi and at WOT my fuel presure was 60psi. Put the guage on again tonight and I still run normal at 50psi but WOT drop's right down to 30psi :shock: Plus I got NO fuel presure when it prime's and soon as I shut off the car, it go's straight to 0 too.



So at least I got the question answered on Y I am going so much slower this year.

Now I just got to figure out what is causeing my loss in fuel presure. I got a funny feeling its the pump itself :? Not sure what else can cause this. Any guesses?

 

Leaky injectors will cause you to loose pressure when you shut the car off, and loosing pressure at WOT means your fuel pump is weak and can't keep up to the demand. Sostar18 had the same thing last year and replaced the pump with a Holley 255gph and it is like driving a new car now. Hope that helps

 

if its the stock pump yer still using then if yer injectors aint leaky like Stiff suggested then for sure it's dying. With the heads/cam you have its on its way out sooner or later no matter what. Even just due to age. Go with an inline holley blue

 

continous usage above 55 psi will kill a pump.IMHO 50 psi is too much for the injectors and the pump.Why do you need it that high?Is that reading with the vacuum hose on or off/plugged?If you need to turn the pressure that high because of lean condition then you need bigger injectors.

Daz

 

I'm with Daz. I killed both my injectors and fuel pump by running too much fuel pressure. 60 PSI is an *** load of fuel pressure.

 

Actual #'s for normal driveing are fluxing between 48 & 50 lb's. Acording to the computer/scanner its running perfect there, not too lean nor rich.

I got no idea what its air/fuel is at WOT but it used to jump up to 58-60psi soon as u punched it. Now it drop's down to low 30's.

I got Accel 24# injectors in it now, I only dyno'd with 271 RWHP so I think they wouldnt be too small, plus they are less then a year old.
I took a look for some Leaky injectors, I cant visibly see any leak's. Any trick's to check/test these?

Any way to test the pump to be sure? Hate to spend all that $ for nothing. Will a new highflow pump be ok at 55lb's +?

This "inline holley blue" pump mount in the stock location?

Sorry for all the questions, I am in one of them spots were I need to learn a few thing's.

 

If this is with the vacuum line on then youre probably hitting past 60 psi. To set the pressure you have to do it with the vacuum line disconnected.Then it goes up once you put the vacuum line on.

Aftermarket pumps are rated up to 60 Psi as well. 24lb injectors is probably enough for what but youre still putting a lot of load on the injectors.What is the fuel injector constant on the chip?I wont be surprised if some of those injectors are on its way out. The aftermarket pump may last (I doubt it) but the injectors wont.

Why is it set at that high anyway? Raising the pressure is just a band aid for lack of or too big off an injector size.

IMHO of course

Daz

 

I thought the Holley Blue pump are for carbs?It doesnt matter since I rather buy my FI pump here.

www.racetronix.com - Its in Scarborough

Daz

 

If you do decide to go with an inline pump, know that they are extremely noisy.

Mine's the blue pump for carbs, and that thing is just downright irritating. I can hear it clearly over the exhaust.

 

Ok, the presure was already set, we just put the guage on it to read it. It was Triggers guage so I dont know how he hooked it up. Seems to work fine on his car so I assume its hooked up right.

The pulses on the chip is set too 19.8. I can get that adjusted but thats were it run's perfect acording to the computer reading's.

So I guess I need one of these then, Part #GRN-GM722-2 Fuel Pump, F-Body, In-Tank, Electric, 255 lph, 90 psi, Chevy/Pontiac Camaro/Firebird?

http://store.summitracing.com/partde...N=120%20304980

 

yes or this..

http://www.racetronix.com/product/RX..._Pump_Kit.html




Daz

 

like i said before

change your filter first. is the cheapest. and could be it for the psi drop

i am not sure that its the pump just yet. there is still a few thing you need to try. it could still be the AFPR

you need to get the gage back on and pinch off the return line. if it maintains psi after the engine running or the first prime then your injectors are not leaking and its your AFPR

also there is a relay that the pump gets it first prime power from but the pump does not use that 12V when the engine is running. i cant remember if i even heard the pump priming????


keep in mind you may be dealing with a few problems.

1 no fuel prime just before starting
2 not holing psi after running
3 psi drop at WOT

 

It does wine as if its priming, so I thought it still was untill the guage was reading nill.

Injectors are NOT leaking, John and I ruled them out today at least. So that leaves pump or AFPR.

As for the fuel filter, I am pretty sure its fine as its not very old, but a new one will prolly be going on tomorow just to be safe.

 

Go with the Walbro 255lph. You can get the low pressure or the high pressure version. On my GTA I picked up a Walbro kit from New Era Performance for my car for about 138 including everything shipped to my door. I picked up the high pressure one. Very quiet pump compared to my stock. Everyone told me it would be a lot more loud.

I also installed the Racetronix kit and upgraded harness on my friends LT1 yesterday and was very happy with the kit. It contained EVERYTHING needed. My vote is with Racetronix as they sell the Walbro255lph in their kit for TPI's. And their harness is awsome. Very well assembled and complete. Have fun dropping the tank if you go that route. I dropped my tank to put my own pump in but my friend had me cut a hole for his and we just swapped it with the tank intact. I must say it was a lot easier than removing everything but I just can't do it to my GTA