charliegt

My starting issue is looking like not enough fuel instead of too much as I originally thought.

When my car has trouble starting the fuel pressure is low (8-12psi). When it starts right up, the pressure is 32psi.

I am going back home this weekend to do more testing, but I thought I'd post this up and see if anyone has ideas.

I just replaced the fuel pump, pressure regulator, vacuum lines, coolant temp sensor, and I had the injectors rebuilt (all of this was in attempt to fix the starting problem).

Right now I'm leaning towards the fuel pump (speed) relay, or the resistor. Does anyone else have any thoughts or suggestions?

Thanks,
-Charlie

RotorJoe

Change your fuel filter while you're at it, just to make sure that thing isn't causing any issues.

But it sounds like you're on the right track. Here are a few threads I remember about this topic and the direction you're heading.

https://www.rx7club.com/showthread.p...el+speed+relay
https://www.rx7club.com/showthread.p...highlight=fuel

charliegt

Thanks for the reply and links Joe. Yeah, I plan on replacing the fuel filter this weekend as well.

-Charlie

DaleClark

iTrader: (55)

Not sure where it is in the FD, but most cars have an anti-drainback valve in the fuel system. This maintains line pressure after the car is shut off - without it, the fuel pressure bleeds back into the tank, and it takes a while to repressurize the system when you start the car back up.

Might be worth checking the fuel pump's O-ring seal - if that's bad, that could be a source of a problem. Also might be worth T-ing a fuel pressure gauge into the fuel feed hose going to the engine to watch fuel pressure.

Dale

charliegt

Quick update. When I had the fuel pressure gauge hooked up today I noticed that when I turn the ignition key to on, the pump does not prime. If I remember correctly, I've read somewhere that the pump should run for 2 seconds when the ignition key is turned to on?

charliegt

Also, when I jump the f/p and gnd the fuel pump comes on fine. It also runs fine (for 2 seconds when I turn on ignition) if I remove the fuel pump relay and jump the terminals with a paperclip.

charliegt

By removing the fuel pump relay and jumping the pump with a paperclip the car starts/runs perfect. So, for one reason or another, the fuel pump is not getting power during startup. I tested both the fuel pump relay, and the speed relay - they both seem to be working correctly.

When I get back in town this weekend I am going to test the continuity between the PCME terminal and the fuel pump relay, although I doubt that is the problem.

Are there any sensors that could go back that would cause the fuel pump not to come on during startup? (even for the 2 second prime).

I occasionally get code 16 (it has been like that since I bought it). It never seemed to cause any problems before so I wouldn't think that it would be causing this - what do you guys think?

-Charlie

charliegt

Bump. I'm also going to check for voltage where the relay plugs in - to see if it is getting energized when the ignition is first turned on.

-Charlie

ARMAN

Any progress?