Alright kids. Car is leaning out as it starts goin- and losing fuel pressure.

Yaj Yak

Gladys
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May 24, 2007
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As we all know my car ran shit last time at the track... cuz i let off every time, not even to the 1/8th yet, as she was going lean as fuccckkk

i have a fuel pressure gauge, just did not have it installed yet....

welp i installed it yesterday and went for some rips today....


car idles around 40psi and...

then i slowly ease into it, fuel pressure rises to around 60psi, and as my car starts moving the fuck out, slowly drops from that 60psi, and as it drops from that 60psi, car goes lean and leaner and leaner and then i get scared and let off... and by now the fuel pressure is below 40....

all the while, my tune has not changed at all, and my car was running fine two weeks ago.




im going to start by snagging a fuel pressure regulator from my 3800 boneyard, as well as replacing the filter...


but then... if that doesn't fix it... dare i say fuelpump?

am i heading in the correct direction?




and if it is in fact the fuel pump... what should I do? who makes what good?
 

shaferz

slaps a ho
Sep 9, 2008
1,294
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Central IL
I wouldn't put a used FPR on the car. Just goto ricer zone and buy a GP sorensen one. I have a used one if you want to just throw it on. If the FP is original it might be time.


I started typing out a response calling you a fucking idiot thinking you were telling kaaayjaaay to run another stock fuel pump, but then realized you were talking about a regulator.


You're on the right track KJ. Try the regulator first for sure. Fuel filter is easy and cheap to replace, so you might as well do that anyway. If neither of those do it, get a new pump. I know the 01+ uses a different fuel tank and setup stuff, but get ahold of PRJ and see if he can get you set with what you need for a racetronix pump.
 

M@

Somebody buy this thing
Nov 26, 2007
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#1, check the entire length of line for even the slightest kink, twist, or other restriction. Those plastic lines are really finicky about flowing right, A little bend, fold, or kink can reaaaaaally cut down your flow.
Cost: Free

#2, replace the filter, cheapo parts store one will be fine, just get a fresh one in there and see what happens. If you've never replaced it before, be prepared for it to not come off...might have to get custom in that case, or at least waste a can of PB Blaster
Cost: 20 bucksish

#3, Regulator, I really don't think this is the problem, as yours is in the right vicinity at idle, and is clearly responding to boost at spool, but it's easy enough to change, and cheapish. You own too many grand prixs not to swap one out.
Cost: Free, minus the cost of all the hand cleaner and towels to clean up the spilled gas.

#4, I think this is going to be the one that does it, new pump. Pony up the cash for a racetronix pump, and never look back. They're expensive, but are a pretty sure bet it seems.
Cost: more than you can afford pal, Ferrari

get some!
 

smug

Please go back to eating crayons
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Aug 4, 2007
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ive done my fuel filter before.... just not too recently...


question here tho- i no longer have my lil schraeder relief valve on the fuel rail- as that is where my fuel pressure gauge ties in... how do i get the pressure out of the rail to remove it?

just let the car sit for a couple hours and then crack open the line where the fuel pressure gauge ties in while holding a rag over it. I think it is time for a new racetronix pump and wire harness from PRJ. For my 01 GTX I had to use the top part of the fuel pump canister from my 01 then use a bottom half of a 98 to 00 GTP style pump canister. It looks like a PITA at first but it is not so bad after all.
 

M@

Somebody buy this thing
Nov 26, 2007
2,871
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find fuel pump fuse, remove, start car, run til it dies, restart, let it die, keep cranking it til you can't hear it fire. Pressure will be almost completely bled off. Let it sit a little longer just to be sure, then go at it. There might still be a smidge of residual pressure, but not much. Schrader valves are overrated.
 

phat_ridegt

TCG Elite Member
Sep 16, 2007
3,351
2
Ottawa
find fuel pump relay, remove, start car, run til it dies, restart, let it die, keep cranking it til you can't hear it fire. Pressure will be almost completely bled off. Let it sit a little longer just to be sure, then go at it. There might still be a smidge of residual pressure, but not much. Schrader valves are overrated.

fixed for ya :smile:

i would first, just pull the vacum line off the regulator and see if it spikes up. drive it like that (plug the vacum line with a screw or something), and see if it drops off.

i agree with what mat said though, start with the easy stuff, if you cant remember how many miles/length of time since you've replaced the fuel filter, its time to change it.

probably not a regulator issue, buts its a good idea to have a sorenson unit in there anyway if you are going to use the racetronix. fwiw, i see around 64ish psi w/ the sorenson regulator, racetronix and harness.



also, how lean is lean? or course it's a problem, but whats the wideband read when the pressure drops?
 
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