headers@fuel pressure

[money pit]

back again with more problems! high idle problem has gone away for those of u that care.here we go i put smooth flow
header system from CC now my plug wires keep melting causing misfire plug head cover only a 1/16 away from header tried plug wire protector
only made prob wores need some ideas.next .went to have car put on dyno found more prob car runing lean has something to do with fuel pressure
put pressure gauge on turn key on sometimes gets to pressure then drops right off sometimes turn key and nothing somtimes turn key gauge goes to 2.3.4.5 psi then drops start car and stays at pressure turn car off pressure drops key off or on put 12 volt to alcl pump goes to pressure and stays take away volts pressure drops.when on dyno we had pressure guage on pressure was good untill wot then pressure droped right down they said this prob is robing me of 30+ hp

 

[tmkassin]

If it works the same as my 92 it sounds like a bad fuel pump. When you turn on the key the fuel pump runs for 2 seconds and shuts off. The pressure should stay at about 40 lbs. If it drops you have one of three issues. Either the fuel pressure regulator is malfunctioning, the fuel pump is defective or you have leaking injectors. Pull the vacuum line from the FPR and check for fuel in the vacuum line. If there is the FPR is bad. If an injector is leaking down it will most likely drop pressure slowly. When the pump goes bad the pressure drop happens instantly. Don't buy a cheap aftermarket fuel pump. They are junk. An OEM pump is only $110 at O'Reillys. Good luck.

 

[money pit]

yes drops rapidly y when i put 12 volt to alcl it runs is the pump supposed to hold pressure? pump 1 year old new injecters and fpr
does any one make plug wires that can touch headers?

 

[money pit]

madadthats all

 

[surfboard]

I has a the similar problem with my 1985. The short hose that went from the pump to the tube cracked.Found out that you need to get a hose that has the nylon center because the ethanol eats up the hose.Standard fuel hose doesn't work even though the parts counter gave me the original tubing and gave me :eyerole when I asked for hose with the nylon center.They didn't have the ethanol blend in 1985.I would follow the factory service manual for fuel pump procedure which is right on except they didn't know about ethanol blend back then.

 

[money pit]

I has a the similar problem with my 1985. The short hose that went from the pump to the tube cracked.Found out that you need to get a hose that has the nylon center because the ethanol eats up the hose.Standard fuel hose doesn't work even though the parts counter gave me the original tubing and gave me :eyerole when I asked for hose with the nylon center.They didn't have the ethanol blend in 1985.I would follow the factory service manual for fuel pump procedure which is right on except they didn't know about ethanol blend back then.

could this problem cause the engine to cut out when i WOT with 1/2 tank or less of gas if so u might have fixed two prblems

 

[money pit]

Should hold pressure at fuel rail until you stop the pump

once u stop pump it should drop to zero? i keep getting conflicting ansewers.

 

[surfboard]

It should hold the pressure.If not you could have a leaking regulator diaphram, a bad fuel pump check valve or a leak at the fuel pump assembly including the fuel pump tubes.

 

[money pit]

your not asking clear questions

1.Pressure should hold and drop slowly when you turn the key off.

2.So long as fuel rail maintains the correct pressure when engine is running
what pressure does when engine is off is of no concern except for ease of starting

3.If loosing pressure at WOT,likely you have a weak pump , blocked filter or the mentioned leak in tank

1. pressure drops fast not slowly. not turning car over just key on goes to pressure thenthen drops fast lees than 1 second
2.exactly ease of starting it is not starting as easy as it did before some times turn key does not get any pressure need to turn key off and try again.
not clear questions. to many weird things happing to narrow down a good ? .so i tell u as much as i can sorry.
i am getting the info i need i need to test a few things just trying to figure out what to atack first with all the info i will check fuel sending uint fist snd work my frontward thank u for your toughts.

 

[money pit]

Pump only runs for 2 sec when you turn the key on



So no pressure is building at the injectors.Need to check the 3 items mentioned in post # 2.
[Clamp the fuel return line at fuel rail and see if pressure holds.If so regulator is faulty
If pressure doesn't hold with return clamped]
, one way valve in tank may be faulty
or the line from pump split as mentioned so fuel leaks back into tank.
This could also explain loss of pressure at WOT because pressure is bleeding off

would have done clamping tests but all the lines are hard lines

 

[Hib Halverson]

"money pit"....first, you need the factory service manual. Next, you need a fuel pressure gauge for a TPI engine. Then you need to run the fuel pressure tests listed in the FSM.

Executive summary:
Turn the key on but don't start. Fuel pressure should rise then the pump turns on to the range listed in the manual. When the pump cuts off after a couple of seconds, the pressure should hold, inside the range listed in the FSM, for a while then very slowly begin to drop. As it drops should stay in the range listed in the manual for a short period, then drop out of it. If the system is functioning properly, it should take hours for it to drop to zero.

If the pressure does not behave that way, there are a number of reasons why it might not and each one is addressed by the FSM.

Whatever you do, it is obvious your engine is running lean under load. I wouldn't drive the car much more until you repair the fuel pressure problem or you risk damage to your engine.

Good luck.

 

[surfboard]

the fuel injection is temper mental to fuel pressure.If your off by as little as 5 lbs. pressure it will run like crap.But when its on the money it runs like hell.If your going to do the work yourself a fuel rail gauge is a must or your going to chase your tail.Nobody here minds giving you help but you'll need at least the fuel gauge.

 

[Paddywhack]

Just say no to inexpensive fuel pumps!

Had the same problem with pressure after building the engine in my '86. Kept on changing fuel pumps ( 4 in one season, all from auto zone). Turn key, pressure would go to just over 40. At shut down, pressure would drop immediately. Occasionally, I would get on it and the engine would sputter. Even at low fuel, 1/4 tank or less, car would run like crap. Finally went to an Edelbrock fuel pump. Keeps pressure long after key is shut off. No more hesitation at WOT or running like crap on low fuel tank. Made a HUGE difference!!!! Good Luck!

 

[money pit]

Are rubber lines at front where fuel enters the rails

all hard all the way back to tank

 

[surfboard]

the rubber lines are under the filler door.Remove the 4 screws holding the door filler plate to the body.Remove the gas cap.Pull the filler neck rubber boot out and you will see the rubber hoses connected to the fuel assembly.Put the gas cap back on.There are three hoses.I believe the one at the lower right is the feed to the fuel regulator.You will need to clamp the rubber hose after someone turns the key to on (not the run position) and count to 2 and clamp it off.Watch the fuel pressure gauge with the clamp left on and see what it does.If it holds note the number on the gauge.wait a few minutes and see if it drops.If not the your regulator is probable good.Take the clamp off and see what happens.If it drops then you have a problem with the fuel pump assembly and or the fuel pump that is attached to it. You can clamp off the tube with anything you want but has to clamp the tubing well.A soft jaw vise grips or vise grips with something that won't cut the tubing can work in a pinch.

 

[surfboard]

your not trying to clamp the return line .You want to clamp the pressure line from the pump after the pump builds up pressure.This is to see if there is a fault with the pump or sending unit.The return line is excess from the regulator. Like I said wasn't sure which line it was.Your link to the article says it all.

 

[money pit]

your not trying to clamp the return line .You want to clamp the pressure line from the pump after the pump builds up pressure.This is to see if there is a fault with the pump or sending unit.The return line is excess from the regulator. Like I said wasn't sure which line it was.Your link to the article says it all.

thank you all for all your help but i give up on this car. trading car,bike and van for 1998 corvette with 28000 miles.
spent way to much time and $ on 85 more time working on it than driving lesson learned