whats the purpose of this? for example, using an aeromotive fuel pressure regulator, a hose coming from the plenum is usually adequate to allow a 1:1 fuel:boost pressure. what's the need for this solenoid?

 

The solenoid switches the source for the FPR from vacuum to atmospheric pressure under certain conditions, usually under hot startups to help prevent flooding.

If you're going with a big fuel system, I'd eliminate it and run the vacuum line straight from the lower intake manifold source to the FPR.

Dale

 

Yes it cuts vacuum to the FPR when fuel temperatures get high enough in order to prevent vapor lock or rough idle. See the service highlights document. Most people consider it an unnecessary bit of over-engineering...

 

yea seems pointless especially when i'm going to be running an aem ems and will be using the o2 feedback. i'll eliminate it

 

I wanted to bring this back, would a leaking/faulty FPR solenoid cause any problems on a stock fuel system?

I know my FPR solenoid leaks as I tested it, so I was thinking of eliminating it, but I don't know if it would be worth it since I don't seem to be having any problems losing fuel pressure. I was thinking of removing it as a fail safe because the solenoid would obviously get worse over time.

 

If its leaking then its either going to be raising or lowering your fuel pressure so I would say thats not ideal. Why dont you just replace the solenoid? If not I thinkkkkkkkkkkkkkkkk the correct resistor to put in the plug is a 1/2 watt 330 ohm resistor.

 

My thing is I don't have any fluctuating fuel pressure issues, so I was going to remove it just to be on the safe side. I have a powerfc so I can just remove it and leave it unplugged, I don't have any more good working solenoids left to replace it, lol.

 

If the solenoid controlling your fpr is leaking then you have fuel pressure rising or falling guaranteed. Have you drove around with a gauge reading your fuel pressure?

 

Yeah I have a gauge, my fuel pressure is perfectly steady though. What I'm having a problem with is I'm not getting fuel pressure with just the key-on, I have to jump the f/p on the diagnostic port to start the car all the time. However I'm pretty sure that's unrelated

 

I would say your fuel pump may be getting a little weak. Check and make sure youre getting battery voltage at the pump.

 

I'm getting the correct low speed voltage (9-10v) to the fuel pump with just the ignition on, but just for a couple of seconds and then the pump shuts off. As I've read it's supposed to do that. But like this I get 0psi fuel pressure, and I don't understand how it's supposed to maintain fuel pressure to start the car if the pump shuts off after a couple of seconds.

If I jump the f/p at the diag. port I get 40psi, and if I jump the circuit-relay itself I get about 30psi and can start the car fine also

once the car is running I get 13v+ at the pump and my fuel pressure is in the low-mid 30's

I've tested and swapped around all the relays and nothing changes. I've also tried it with the fuel pump resistor connected and jumped, and still no difference.

 

When it comes on with the key forward its supposed to be priming your fuel pressure. Not supposed to be at zero psi. How old is the pump and the filter? If there both old im pretty sure their lies your problem.

 

So you're saying the fuel pump should stay on all the time when just the ignition is on

 

Sorry forgot to say the rx7 is one of those cars that gets cranking fuel pressure. key on only builds fuel pressure when terminals fp and gnd are jumped. While cranking if your not seeing the fuel pressure rise then your pump is probably dieing. If your fuel filter is old swap it out. If its clogged it will put alot of stress on your pump.

 

Thats if youre sure youre getting the proper voltage out to the pump while cranking.

 

I'll have to check the pressure and voltage while cranking. I have an electronic f/p gauge, so I'll have to power it continuously so it can stay on while cranking.

For now I just have the circuit relay jumped