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Help FC wont start.....again...

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Old Dec 7, 2006 | 08:25 AM
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CptnObviousFC's Avatar
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Help FC wont start.....again...

Ok about two days ago or so i had a problem with my engine getting fuel, it turned out to be a fuel pump relay. So i replaced the relay and the car started up agian. now it has gone back to not starting. I am also not reading any voltage to my fuel pump when i turn the key to the "on" position. There are a couple of questions i have.

Which wire to the pump should i be checking for voltage, because the last connector before the fuel pump i get no voltage on the connector that connects to the power wire for the pump, none on the ground obviously, and a couple of volts on the other two like 2.5 on one and about 7 on the other. There are four wires here that all go to the fuel pump.

Also I already checked to see if it was the same relay and when i tested the relay it was still good, I also checked all of the other relays that I think connect to my fuel system.

Also could my MAF be causing my car not to start?? Any help would be greatly appreciated.
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Old Dec 7, 2006 | 08:37 AM
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Aaron Cake's Avatar
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I don't think you'll see 12V at the pump unless the car is running or you have jumped the test connector at the passenger shock tower (yellow two prong connector). The fuel pump won't run without a signal from the AFM (S4) or ECU (S5).

As I recall, it is the thick blue wire you should be checking, but I could be wrong so check the wiring diagrams in the Haynes/FSM.
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Old Dec 7, 2006 | 10:49 AM
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Still running a Walbro 255 on an n/a with a stock pressure regulator?
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Old Dec 7, 2006 | 02:31 PM
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no i put the stock pump back in
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Old Dec 7, 2006 | 02:55 PM
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From: Rohnert Park CA
Originally Posted by CptnObviousFC
Ok about two days ago or so i had a problem with my engine getting fuel, it turned out to be a fuel pump relay. So i replaced the relay and the car started up agian. now it has gone back to not starting. I am also not reading any voltage to my fuel pump when i turn the key to the "on" position. There are a couple of questions i have.

Which wire to the pump should i be checking for voltage, because the last connector before the fuel pump i get no voltage on the connector that connects to the power wire for the pump, none on the ground obviously, and a couple of volts on the other two like 2.5 on one and about 7 on the other. There are four wires here that all go to the fuel pump.

Also I already checked to see if it was the same relay and when i tested the relay it was still good, I also checked all of the other relays that I think connect to my fuel system.

Also could my MAF be causing my car not to start?? Any help would be greatly appreciated.
Unless you have the diagnostic jumper in place for the fuel pump, the fuel pump will not be powered unless you have the key in the start position or the AFM sees air movement from the engine running.

So, the AFM is not even used when the key is cranking.

But just turning the key on, will not power up the fuel pump
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