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-   3rd Generation Specific (1993-2002) (https://www.rx7club.com/3rd-generation-specific-1993-2002-16/)
-   -   question for the pros (https://www.rx7club.com/3rd-generation-specific-1993-2002-16/question-pros-294798/)

darrenm 04-14-04 07:20 PM

question for the pros
 
ok, I recently replaced the motor and turbo. everything ran well for about 1500 miles. then the car stalled while at low speed like it ran out of gas.
The fuel pump is not getting primed when I try to start it. I checked the relay. the relay itself is good. I checked the fuel pump resistor. My voltmeter reads the resistance across the unplugged resistor at 1.8 ohms, that's about twice what the manual says it should read, but I figure it must still be functional. if the resistor burned out the ohms would be extremely high, right? anyway, I can use a jumper wire at the relay and the fuel pump will run continuous with the key on and it does shut off with the key off.
the engine will not start otherwise. any ideas on what else may be in the circuit?
impress me...

tiger18 04-14-04 09:21 PM

Right im no expert but from what ive read its basically straight forward, , if you say you use a jumper wire and the fuel pump works fine that rules out the pump,,,so its gotta be one of the controlling circuits.,
first things to check are the 2 relays,,,
1)circuit opening relay
2)fuel pump relay
i presume you have the knowledge to check these,,,
,,the next thing to check is the wiring from these 2 relays to the ECU,,,because at the end of the day the ECU controls the pump through them..

and the last thing is the fuel pump resistor,,, i dont think it should read over 1ohm,,,,so that could really be your problem as the resistor is basically a speed controller for the pump ,,,the higher the resistance the lower the voltage to the pump,,,maybe its just to high and the pump isnt getting enough juice,,,,try borrowing a friends,,,worth a try..
i personally think it will be a crappy relay,,again try a friends,,,,get him to lend you them (both of them)
ok,,,let me know how you get on

tiger18 04-14-04 09:24 PM

good place to look page 108 in the manual ,(fuel exaust and emmison control)its very basic and easy to understand

felix_is_alive 04-14-04 09:27 PM


Originally posted by tiger18
im no expert

he clearly stated he needed an expert
thats just not cool

tiger18 04-14-04 09:30 PM

i didnt see no expert replies,,,just trying to point the guy in the right direction,,,,im sure he would rather get some info than none

black99 04-14-04 09:33 PM

lol I think he was kidding.. At least I hope..


Wish I could help, but don't have anything to add..

felix_is_alive 04-14-04 09:35 PM

i am just messing with you man ... what you said makes sense

mad_7tist 04-14-04 10:26 PM

sometimes relays will become pitted inside and will hold and then fail after a bit. when it is not starting you stick the jumper across the relay and it starts? if so you have found the problem or a great starting point. the relay is bad or the controll signal to it is getting interupted.

DMRH 04-15-04 12:49 AM

The fuel pump circuit runs through the resistor via a relay. Check this "resisitor relay" as the contacts of it may be pitted.

Since its happening at low RPM, the FP power is going through the resistor via the FP resistor relay.

Also check that the resistor relay is getting its NEG trigger from the ECU.

REgards

spyfish007 04-15-04 01:31 AM

Could be a bad fuel filter as well. Get a fuel gauge and follow the factory test for testing fuel pressure & fuel pump.


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