Need help fast!!! This afternoon!!!

forpit2000gt · Aug 24, 2005

It would really help to put a fuel pressure guage on there and see what is happening. You need to replace fuel filter if you haven't already. I would really guess it is the fuel pressure regulator. I don' know what the stock one costs but you can buy and aftermarket one thatis adjustable for a little over $ 100.00. If you can turn the key on several cycles and then crank right away, FPR is my best guess. Our newer cars have a returnless fuel system and don't have your setup. You have a return style fuel system. Until the fuel pressure is 30lbs or better it will not crank. It will go up to about 39 lbs and stay there if all is well.

95 GT · Aug 30, 2005

forpit2000gt said:
It would really help to put a fuel pressure guage on there and see what is happening. You need to replace fuel filter if you haven't already. I would really guess it is the fuel pressure regulator. I don' know what the stock one costs but you can buy and aftermarket one thatis adjustable for a little over $ 100.00. If you can turn the key on several cycles and then crank right away, FPR is my best guess. Our newer cars have a returnless fuel system and don't have your setup. You have a return style fuel system. Until the fuel pressure is 30lbs or better it will not crank. It will go up to about 39 lbs and stay there if all is well.

Thanks man! It sounds like you really know what you are talking about. I will change the filter just because it is an unknown quantity but I dont understand how a clogged fuel pump is going to cause a loss of fuel pressure while the car is parked overnight. I have ordered a fuel rail pressure gauge and will install it this weekend and report back. There is absolutely no fuel smell, so if there is a leak it is into the engine (leaky injector?) And it seems to take about half an hour to bleed from 30-40 psi down to where it will turn over for a few seconds before firing.

forpit2000gt · Aug 30, 2005

the fuel pressure regulator on your car lets fuel flow back to the fuel tank through a return line, you will not smell anything. The aftermarkets, aeromotive or bbk is what I have used. I prefer aeromotive though. A fuel pressure guage will let you see what the pressure is and it should not drop more than a couple of psi sitting. The aftermarket units let you raise the fuel pressure if needed. mostly stock 39-40 is normal. when pressure gets above that the regulator lets off pressure .

95 GT · Sep 1, 2005

Thanks for all the responses guys. Changed the fuel filter. Car runs fine (it was starting to miss at partial throttle). Some nasty dark fuel stuff came out of the filter and it was Motorcraft so it might be 8 years old. Still have no fuel pressure after sitting for more than a half hour. I think I am down to only 2 possiblities. Since when I turn the car off it has good fuel pressure, then a half hour to an hour later it has lamost none.
1. The fuel is leaking back down the supply line past the pump into the tank.
or
2. The fuel is flowing down the return line after shutdown.
Since the car is supposed to maintain pressure while sitting, what stops it from all going down the return line back into the tank?

forpit2000gt · Sep 1, 2005

95 GT said:
Thanks for all the responses guys. Changed the fuel filter. Car runs fine (it was starting to miss at partial throttle). Some nasty dark fuel stuff came out of the filter and it was Motorcraft so it might be 8 years old. Still have no fuel pressure after sitting for more than a half hour. I think I am down to only 2 possiblities. Since when I turn the car off it has good fuel pressure, then a half hour to an hour later it has lamost none.
1. The fuel is leaking back down the supply line past the pump into the tank.
or
2. The fuel is flowing down the return line after shutdown.
Since the car is supposed to maintain pressure while sitting, what stops it from all going down the return line back into the tank?

Fuel pressure regulator is what stops the fuel from going down the retun line.

95 GT · Sep 1, 2005

forpit2000gt said:
Fuel pressure regulator is what stops the fuel from going down the retun line.

OK. That's next on my list then. Wish me luck. My Fuel Rail Pressure gauge should be here tomorrow as well. I will install one or both and post the results. Thanks.

95 GT · Sep 1, 2005

Oh yeah. I just had a thought. Any chance a leaky injector is letting it bleed down by dripping it into a cylinder? Car only has 58k miles.

blackink00 · Sep 1, 2005

i could be wrong but forpit is wrong about the regulator because the 98s was a returnless fuel system and it doesnt have an adjustible fuel regualator. 98s was the only the only year to have a returnless fuel system but not be the same as a 99+. my 98s the same way and i would just skip everything and just get a pump.

forpit2000gt · Sep 1, 2005

a lot of what we talk about on here can easily be wrong but going from past experience, I have seen this and it most always has been fuel pressure regulator bad.
I'm also wrong about something every day........it's taken me about 20 years to admit I can be wrong, I must be getting old.

blackink00 · Sep 1, 2005

it could be but let him do it and get back to us if it works. how much is a new regulator? i might try that. is there any way to test it?

forpit2000gt · Sep 2, 2005

you know this may be a time I'm wrong. I have to do some checking now.
94-97 5.0 and 4.6 use the same regulator. 98 2v 4.6 may be different. 98 4v did have return style system. Maybe the 98 2v didn't . I will find out. If someone knows for sure chime in.

forpit2000gt · Sep 2, 2005

Kirban, Aeromotive and BBK don't list a regulator for 98 2v, 94 through 97 , 5.0, 4.6 2v or 4v and 98 4v. nothing about 98 2v. If this is so the fuel pump is leaking down.

blackink00 · Sep 2, 2005

so its not the regulator? am i right then? it is the pump

forpit2000gt · Sep 2, 2005

98 2v 4.6 = returnless
yes , I believe the pumps leaking back into the tank.

blackink00 · Sep 2, 2005

so he replaces the pump and the problem is fixed? if so i want to do mine. i just replaced teh pump in my sisters truck tonight and it took me and my buddy about 2 hours. its a 99 chevy truck, also the pump was $250. :o

ADRENLN · Sep 2, 2005

same thing has been happening to my car for about a year. 2002 gt 10,000 miles. i guess ill find the problem somewhere along the modding way.

i just hope what ever it is dont completely fair before i find it.

mrvax · Sep 2, 2005

The 1998 4.6L 2v has a hybrid RETURN style fuel system.

forpit2000gt · Sep 2, 2005

mrvax said:
The 1998 4.6L 2v has a hybrid RETURN style fuel system.

do you have any other info on this?

95 GT · Sep 2, 2005

Obviously I can't speak for everybody. But my 1998 2V GT has a Hybrid return system different from the 96 and 97. It does indeed have a Fuel pressure reg on the fuel rail. I bought a new one @ Auto zone for $50. I will install it and let you know. I have a fuel pump from a 1992 that I may work since they are WAYYYYYYYYY expensive. Also. In the 5.0 world, pumps always get real noisy for months and even years before they get bad enough to affect drivability. I'll keep you posted. Looks like the regulator is leaking back to the tank.

95 GT · Sep 9, 2005

Fuel Pressure Update

OK. So here's the deal. I have replaced my fuel filter. It was yucky, but had little effect on drivability. Maybe a little better, maybe the same. I bought a new Fuel Pressure regulator, but they are not replaceable on the late 1998 cars. They are welded onto the fuel rail. I did install a Accel Fuel Pressure guage on the schrader valve. Here is the deal. After sitting for 1/2 hour Fuel pressure is @ 3 PSI. Turn key to "on" but not all the way to start, pump kicks on for 3 seconds and pressure goes to 42 PSI. Pump Turns off and Pressure drops to 15 PSI within seconds. I can repeat this process 3 or 4 times but the effect is the same. Within seconds the pressure is 15 PSI and from there it slowly (about 1/2 hour) bleeds to 3 PSI. If I get it to 15 and start the car, it goes right up to 40 PSI while cranking and then drops to 35 PSI when it fires. So what we know for sure is;
1. My fuel system cannot hold more that 3 PSI for any amount of time.
2. There are no external leaks in the fuel system.
3. My pump is capable of bringing the system up to 42 PSI and maintaining 35 PSI.

This leads me to beleive that
A. Fuel is getting back to the tank either by flowing past the pressure regulator through the return system which means a bad regulator, which means I have top change out my entire fuel rail system $$$$$$$$$$$$$.
B. Fuel is getting back to the tank by flowing back past the pump which means bad pump, but the 42 PSI kind of makes this less likely.
C. Fuel is leaking out 1 or more injectors that are stuck open

But even though it is running king of rough, it still has ALL of it's power when I get on it which I think rules out B and C. I mean if the pump is shot how is it going to deliver enough fuel for full power @ 6000 rpm? Along the same vein, if an injector or 2 is stuck open all the time, what are the chances that the mixture would be correct to make full power when I get on it from idle to redline?

Any thoughts or advice are greatly appreciated. Thanks again for all the feedback so far.

Need help fast!!! This afternoon!!!

forpit2000gt

95 GT

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95 GT

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blackink00

I missed a shift & stole Curt's money.

forpit2000gt

blackink00

I missed a shift & stole Curt's money.

forpit2000gt

forpit2000gt

blackink00

I missed a shift & stole Curt's money.

forpit2000gt

blackink00

I missed a shift & stole Curt's money.

ADRENLN

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mrvax

Stay thirsty my friends

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I missed a shift & stole Curt's money.

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Stay thirsty my friends

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