sputtering/falls over
08-04-2014, 07:57 AM
#1
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Car: 92' Formula T-Top
Engine: L98 With Custom CAI
Transmission: BUILT 700R4 with B&M Mods
Axle/Gears: 3.23
sputtering/falls over
92 formula with L98.
Having an issue with when I take off from a light it hesitates and then almost spudders out or falls over.
I did a fuel pressure test a idle is 35 pounds when I get on the gas it drops down and the harder I get on it it actually gets below 20 pounds.
when it starts to sputter a different IP ranges around 2500 to 3000 the needle on the fuel pressure gauge starts to shake erratically.
Replaced the fuel filter and still does this. Just did the pump 5 months ago.
Could the pump be the issue again?
Having an issue with when I take off from a light it hesitates and then almost spudders out or falls over.
I did a fuel pressure test a idle is 35 pounds when I get on the gas it drops down and the harder I get on it it actually gets below 20 pounds.
when it starts to sputter a different IP ranges around 2500 to 3000 the needle on the fuel pressure gauge starts to shake erratically.
Replaced the fuel filter and still does this. Just did the pump 5 months ago.
Could the pump be the issue again?
08-04-2014, 09:05 PM
#2
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Car: 1985 & 1991 Trans Ams
Engine: 350 in both
Transmission: Auto in both
Axle/Gears: 3:23 Limited Slip in both
Re: sputtering/falls over
Sounds a bit like what I just went through with my L98. Hesitation which finally got so bad that it would idle but would die upon acceleration. Mine would run great until it warmed up. The cure for mine was a set of injectors and a fuel pressure regulator. Only two of my injectors showed to be bad but I decided it was time to replace them all.
08-05-2014, 02:27 AM
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Car: 92' Formula T-Top
Engine: L98 With Custom CAI
Transmission: BUILT 700R4 with B&M Mods
Axle/Gears: 3.23
Re: sputtering/falls over
Funny you say that. Until it warms up. Exactly what mine does. It's bad azz till it gets about 160. Then the fall over happens.
Was wondering same thing about regulator. What brand of both did you go with for both injectors and regulator?
The regulator would cause the low pressure at WOT I imagine too.
Was wondering same thing about regulator. What brand of both did you go with for both injectors and regulator?
The regulator would cause the low pressure at WOT I imagine too.
08-05-2014, 07:58 PM
#4
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Re: sputtering/falls over
the stock injectors have a tendency to develop coil failure when they are hot. If you are planning on replacing your injectors, do yourself a favor and get yourself a set of bosch lll's. Best injectors hands down.
08-05-2014, 10:38 PM
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Car: 1985 & 1991 Trans Ams
Engine: 350 in both
Transmission: Auto in both
Axle/Gears: 3:23 Limited Slip in both
Re: sputtering/falls over
I purchased a set of the Bosch IIIs from Southbay along with the diaghram for the pressure regulator. Best purchase I ever made and I did it myself since the local dealership wanted over $2,500.00 to do it. My car runs like new now but I would suggest you find someone who can diagnose it for you to make sure that is what your particular problem is.
08-06-2014, 11:10 AM
#6
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Car: 92' Formula T-Top
Engine: L98 With Custom CAI
Transmission: BUILT 700R4 with B&M Mods
Axle/Gears: 3.23
Re: sputtering/falls over
So what I'm wondering is if it's a regulator issue maybe. Guess I'll be looking into finding a new intake and get it all together that way... It acts as though it's starving for fuel. Even cold now it does this.
08-06-2014, 02:08 PM
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Car: 1989 IROC & ROLL-Z
Engine: L98 Vortec FIRST TPI
Transmission: T56, Mech Speedo
Axle/Gears: G92 J65 3.27
Re: sputtering/falls over
Do a real fuel pressure test and report the results, you'll get better suggestions.
You are looking for the following:
Fuel pressure at idle with vacuum hose on your regulator DISCONNECTED (plug the intake part so you dont create a vacuum leak)
Leave gauge hooked up, hose disconnected. Turn engine off, watch fuel pressure. What does it do? IE bleed off immediately, bleed off slowly in the first 10 seconds? 20 seconds? minute?
You are looking for the following:
Fuel pressure at idle with vacuum hose on your regulator DISCONNECTED (plug the intake part so you dont create a vacuum leak)
Leave gauge hooked up, hose disconnected. Turn engine off, watch fuel pressure. What does it do? IE bleed off immediately, bleed off slowly in the first 10 seconds? 20 seconds? minute?
Last edited by Keoman; 08-06-2014 at 02:13 PM.
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08-28-2014, 07:06 PM
#8
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Car: 92' Formula T-Top
Engine: L98 With Custom CAI
Transmission: BUILT 700R4 with B&M Mods
Axle/Gears: 3.23
Re: sputtering/falls over
Ok I finally did the test as you said.
With the hose disconnected idle pressure is 42psi.
As I raise the idle it drops at one point it hits >15psi.
When I hook the hose back it immediately dropped the pressure to 34psi and again the pressure dropped rapidly when the idle comes up and it begins to sputter as well.
With the hose off pressure at 42psi I shut the engine off with no pressure loss after 5 min.
With the hose disconnected idle pressure is 42psi.
As I raise the idle it drops at one point it hits >15psi.
When I hook the hose back it immediately dropped the pressure to 34psi and again the pressure dropped rapidly when the idle comes up and it begins to sputter as well.
With the hose off pressure at 42psi I shut the engine off with no pressure loss after 5 min.