C4 Fuel Pump Problem
Thread Starter
8th Gear
Joined: Aug 2015
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C4 Fuel Pump Problem
My C4 Fuel Pump won't work. No power.
Last year the fuel pump worked. Battery went dead. Installed new battery. Fuel pump solenoid clicked. No power to the fuse. Bypassed the fuse with a wire from the battery to the output side of the fuse. Still no power to the fuel pump. No evidence of mouse chewing. No emc codes except 12. Fuel pump was new last year and worked fine with 47 psi to the fuel log.
Last year the fuel pump worked. Battery went dead. Installed new battery. Fuel pump solenoid clicked. No power to the fuse. Bypassed the fuse with a wire from the battery to the output side of the fuse. Still no power to the fuel pump. No evidence of mouse chewing. No emc codes except 12. Fuel pump was new last year and worked fine with 47 psi to the fuel log.
Le Mans Master
Joined: Sep 2009
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From: My interests are mobile
Tadge was still in college when this car came out....why you askin in here...lol....jk
Wrong forum bro...you need moved OUT noob
If you've confirmed no power at the fuel pump, check the fuse first (keep it easy), then move forward in the system to the relay, from there possibly ignition switch...need a flowchart/diagram/book. I don't have my helms handy at the moment. I'm assuming you've confirmed power in the car, car turns over normally, just won't start, etc.
Wrong forum bro...you need moved OUT noob
If you've confirmed no power at the fuel pump, check the fuse first (keep it easy), then move forward in the system to the relay, from there possibly ignition switch...need a flowchart/diagram/book. I don't have my helms handy at the moment. I'm assuming you've confirmed power in the car, car turns over normally, just won't start, etc.
Last edited by RC000E; Aug 15, 2015 at 10:30 AM.
Race Director
Joined: Apr 2002
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From: Anaheim CA
When the ignition is first turned on the ECM turns on the fuel pump (via the fuel pump relay) for 2 seconds to prime the fuel rails for starting. If the engine is not started the fuel pump will shut off.
When you crank the engine the ignition module inside the distributor (assuming '84 through '91 - similar for LT1s) will generate DRPs (Distributor Reference Pulses). When the ECM sees DRPs it turns on the fuel pump. What all this means is that the fuel pump will not run unless the engine is rotating (whether cranking or running). There will be no voltage on the FP fuse.
We need a year to be more specific on what to check and what to look for...
When you crank the engine the ignition module inside the distributor (assuming '84 through '91 - similar for LT1s) will generate DRPs (Distributor Reference Pulses). When the ECM sees DRPs it turns on the fuel pump. What all this means is that the fuel pump will not run unless the engine is rotating (whether cranking or running). There will be no voltage on the FP fuse.
We need a year to be more specific on what to check and what to look for...
Thread Starter
8th Gear
Joined: Aug 2015
Posts: 8
Likes: 0
C4 Fuel Pump problem
When the ignition is first turned on the ECM turns on the fuel pump (via the fuel pump relay) for 2 seconds to prime the fuel rails for starting. If the engine is not started the fuel pump will shut off.
When you crank the engine the ignition module inside the distributor (assuming '84 through '91 - similar for LT1s) will generate DRPs (Distributor Reference Pulses). When the ECM sees DRPs it turns on the fuel pump. What all this means is that the fuel pump will not run unless the engine is rotating (whether cranking or running). There will be no voltage on the FP fuse.
We need a year to be more specific on what to check and what to look for...
When you crank the engine the ignition module inside the distributor (assuming '84 through '91 - similar for LT1s) will generate DRPs (Distributor Reference Pulses). When the ECM sees DRPs it turns on the fuel pump. What all this means is that the fuel pump will not run unless the engine is rotating (whether cranking or running). There will be no voltage on the FP fuse.
We need a year to be more specific on what to check and what to look for...
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Check the connector at the rear of the car for the fuel level sender and fuel pump. You might have a bad connection there (like a corroded connector pin).
This is the fuel pump wiring diagram for my '86. Your relay pin letters will be different because they changed to a different type of relay in 1987 or 1988. The basic connections are still the same:
This is the fuel pump wiring diagram for my '86. Your relay pin letters will be different because they changed to a different type of relay in 1987 or 1988. The basic connections are still the same:
Thread Starter
8th Gear
Joined: Aug 2015
Posts: 8
Likes: 0
89 Corvette Fuel Pump Problems
Check the connector at the rear of the car for the fuel level sender and fuel pump. You might have a bad connection there (like a corroded connector pin).
This is the fuel pump wiring diagram for my '86. Your relay pin letters will be different because they changed to a different type of relay in 1987 or 1988. The basic connections are still the same:
This is the fuel pump wiring diagram for my '86. Your relay pin letters will be different because they changed to a different type of relay in 1987 or 1988. The basic connections are still the same:
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From: Anaheim CA
Team Owner
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I believe that in that wiring diagram when they reference "rear body connector" they're actually referring to C402 (maybe), I don't have an '89 FSM, which depending on coupe or 'vert has a different location and might have a different reference (C401 maybe).
I generally reference the 8A-section for wiring and if you check the 8A-20-6 OR close for fuel delivery, the page following is the component locator. I don't have an '89 FSM but the 8A-20-6 I believe should be consistent year to year. Some years have different component views listed in the 8A-201 section of book 2.
The connector at the fuel tank meter I don't believe carries an actual reference on most years.
The actual CONNECTOR trail to the rear of car might likely be C237, C209, then C401/402 or what ever. An '89 FSM 8A-20-6 should sort that for you. I would think you would check connector to connector (front to rear) BUT maybe start at the last and work forward until you found the last solid signal.
I generally reference the 8A-section for wiring and if you check the 8A-20-6 OR close for fuel delivery, the page following is the component locator. I don't have an '89 FSM but the 8A-20-6 I believe should be consistent year to year. Some years have different component views listed in the 8A-201 section of book 2.
The connector at the fuel tank meter I don't believe carries an actual reference on most years.
The actual CONNECTOR trail to the rear of car might likely be C237, C209, then C401/402 or what ever. An '89 FSM 8A-20-6 should sort that for you. I would think you would check connector to connector (front to rear) BUT maybe start at the last and work forward until you found the last solid signal.
Last edited by WVZR-1; Aug 18, 2015 at 08:42 AM.
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Race Director
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From: Anaheim CA
I went through my FSM page by page and cross referenced all the connectors. Many are not numbered and the "rear body connector" is one of them. That's why there is no number on that one in my diagram (which is highly modified to reflect reality rather than the barely usable one in the FSM - for example, the FSM diagram does not show the FP fuse or the fusible link).
Team Owner
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I went through my FSM page by page and cross referenced all the connectors. Many are not numbered and the "rear body connector" is one of them. That's why there is no number on that one in my diagram (which is highly modified to reflect reality rather than the barely usable one in the FSM - for example, the FSM diagram does not show the FP fuse or the fusible link).
I do know that on an '87 it does display the connector trail with the connector at the tank displayed as only a C with the appropriate break signifying a connector (the C should be the cavity at that connector), and the OP has an '89 so I suspect that his will also. I've actually looked and I'm very confident. In a later '91 FSM the connector at the fuel tank is referenced as C450.
This is what I would expect in an '89 FSM 8A-20-6
Perhaps the OP will revisit and confirm.
Last edited by WVZR-1; Aug 19, 2015 at 05:52 AM.
Race Director
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From: Anaheim CA
The "C" is the cavity identifier. A and B are the fuel level sender reference voltage and signal pins.
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Cruising
Joined: Mar 2021
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From: Terryville ct
Did you find the bad connection to the fuel pump? I have a 1992 and power at the fuse which tells me the relay is working. But I have no 12v at the pump. Looks like there is nothing inbetween.
Thanks
Thanks