how to tell if regulator is bad?
Thread Starter
Joined: Mar 2003
Posts: 8,319
Likes: 1
From: North Carolina
how to tell if regulator is bad? just like the title says, i need to figure out if its the regulator or the check valve in the pump. after the pump install the car has a hard time starting and noone has been able to tell me a way to find out which one it is. the only time i can get the car to fire the first time to so do it right when the pump gets to the end of priming the system. then it starts and seems to react the same as before. let me know please becuase if there is a problem the pump is going to be sent back asap
a fuel pressure gauge to go on the fuel rail. you can rent one or borow from most car shops like NAPA. you could buy one but $$ just to test.... make sure the gauge reads up to at least 60psi
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First step: Hook the fuel pressure gauge up on your diagnostics port under the hood.
Second step: Have a friend sit inside your car and turn the key to the "on" position.
Third step: Watch the fuel pressure gauge.
The pressure should rise to roughly 60psi and hold there if the check valve is working as it should. Just keep in mind that not all setups use a check valve. My Racetronix pump / Aeromotive regulator has no check valve in it, so if I turn the key on, the pressure builds to 60psi, then drops off pretty quickly.
Second step: Have a friend sit inside your car and turn the key to the "on" position.
Third step: Watch the fuel pressure gauge.
The pressure should rise to roughly 60psi and hold there if the check valve is working as it should. Just keep in mind that not all setups use a check valve. My Racetronix pump / Aeromotive regulator has no check valve in it, so if I turn the key on, the pressure builds to 60psi, then drops off pretty quickly.
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Verdad Gallardo Thread Starter
Joined: Mar 2003
Posts: 8,319
Likes: 1
From: North Carolina
i have no pressure with the key on, i pushed the valve in with the key on about 10 sec after i turned it on not a hiss at all from the schrader valve. when you start yours do you just have to start at the end of the prime cycle??
Not really, no. The pressure actually comes up pretty fast, so it's not much of an issue. I usually let it prime for maybe half a second before I crank it, but that's just because I'm ****. 
Try having a friend turn your key on while you put your head near the gas tank. See if you can hear the sound of gas splashing inside your gas tank.
Also, you did put gas in it, right?
Try having a friend turn your key on while you put your head near the gas tank. See if you can hear the sound of gas splashing inside your gas tank.
Also, you did put gas in it, right?
Thread Starter
Joined: Mar 2003
Posts: 8,319
Likes: 1
From: North Carolina
yeah there is gas in it, i have yet to fill it up all the way though. like i said once the car starts there seem to be no issue at all. see if i can hear gas splashing? what would this determine? ill give it a shot
when you turn the key on with a gauge on it, it should jump up to around 60psi instantly. If it doesn't, your problem isn't in the regulator. The regulator is supposed to keep pressure in the line. The pump runs with the ignition on (don't start the car) for about three seconds. In that time the gauge should move. It sounds to me like the pump would be bad if you had no fuel pressure.
Thread Starter
Joined: Mar 2003
Posts: 8,319
Likes: 1
From: North Carolina
i have fuel pressure it just wont keep it after the pump turns on the first time. they have been telling me it is a check valve in the pump and i dont know how to tell the difference. so the regulator keeps pressure of the check valve keeps it? im confused
Thread Starter
Joined: Mar 2003
Posts: 8,319
Likes: 1
From: North Carolina
im going to be getting the gauge tomorrow to check it out, it should be right around 60 right? i just want to know for tomorrow so when i see the pressure reading ill know what it means so if i have to order something then i can. but i dont know what the pressure is when the car is running yet. like i said i shoudl find out tomorrow a friend is getting me a gauge
Originally Posted by WS6FirebirdTA00
i have fuel pressure it just wont keep it after the pump turns on the first time. they have been telling me it is a check valve in the pump and i dont know how to tell the difference. so the regulator keeps pressure of the check valve keeps it? im confused
The regulator basically provides resistance to the flow of fuel so the system only see's 60psi. Imagine it as a spring loaded valve that takes X amount of force to open up the valve. The magic number in this case is 60psi, so if it goes over 60psi, the valve is pushed open further so more fuel flows through, keeping the system at 60psi. If it's less than 60, it shuts more so the pressure is raised.
The check valve basically just keeps fuel from running back into your tank if the pump isn't actively pumping fuel through the fuel line (key is off).
What I was hinting at with the listening for the gas comment, was that maybe your line inside the tank isn't sealed up well. When you turn the key on and it primes, if your clamp isn't holding the line on well enough, fuel will spray out the sides and you lose pressure. You might be losing enough pressure that your car won't even run.
Thread Starter
Joined: Mar 2003
Posts: 8,319
Likes: 1
From: North Carolina
ok thanks for the explanation, so if i turn the key on and the pressure goes to 60 im good at the regulator, but if it drops off then either the check valve is bad or the line is loose. i made sure that line was tight when i put it on but its possilbe the line could be damaged. ill check it out this morning if my friend has one, if not ill have to go buy one
Thread Starter
Joined: Mar 2003
Posts: 8,319
Likes: 1
From: North Carolina
ok so i tested it right after the pump stopped the pressure dropped, i ran to the back and at the end of priming i heard a small hissing, just like pressure being released back into the gas tank. so that means i should check out my fuel line in there and if its not that then its the check valve right? and by fuel line i mean the one right off the pump to the whole sending unit