Repeated Fuel Pump Relay Failure
05-26-2009, 04:42 PM
#1
Fleet of Foot
Rennlist Member
Rennlist Member
Thread Starter
Repeated Fuel Pump Relay Failure
I have noticed a recent fuel pump relay fault in my car that I am hoping is not a symptom of nastier things to come. It goes like this... car starts and runs fine for quite some time, days in fact. It can be hot or cold. Then, car will crank/no start, spark is fine. Jumpering the fuel pump relay (XX) will engage the fuel pump and the engine starts right up. Remove jumper, install another relay and good to go. I have used repeatedly the same 3 relays, the contacts between terminals 30 & 87 appear to have some oxidation which I will remove, but have continuity, Two of the relays are of the old metal case variety and one is a new black plastic case type. The relays are not inordinately hot to the touch nor is there any burning smell.
I am beginning to wonder if I am seeing a symptom of impending LH failure here. The fuel pumps are both @ 2.5 years old. Other than this, the engine is running very well. Anyone else out there have any BTDT experience with this kind of problem?
I am beginning to wonder if I am seeing a symptom of impending LH failure here. The fuel pumps are both @ 2.5 years old. Other than this, the engine is running very well. Anyone else out there have any BTDT experience with this kind of problem?
05-26-2009, 04:59 PM
#2
Rennlist Member
I'd also clean up the oxidation that you can see and consider removing the panel and see whats behind.
05-26-2009, 05:38 PM
#3
Team Owner
Have you done a blower box reseal??
If your finding corrosion then this could be part of your problem a wet blower box dripping onto your CE panel
If your finding corrosion then this could be part of your problem a wet blower box dripping onto your CE panel
05-26-2009, 05:53 PM
#5
Drifting
How old is your ignition switch? These are known to typically go bad after several tens of thousand miles.
The fuel pump relay's coils get power from the ignition switch, while the fuel pumps get power directly from the battery via the fuel pump relay contacts. So if your ignition switch is malfunctioning during cranking.. no fuel.
The fuel pump relay's coils get power from the ignition switch, while the fuel pumps get power directly from the battery via the fuel pump relay contacts. So if your ignition switch is malfunctioning during cranking.. no fuel.
05-26-2009, 06:14 PM
#6
Three Wheelin'
I have noticed a recent fuel pump relay fault in my car that I am hoping is not a symptom of nastier things to come. It goes like this... car starts and runs fine for quite some time, days in fact. It can be hot or cold. Then, car will crank/no start, spark is fine. Jumpering the fuel pump relay (XX) will engage the fuel pump and the engine starts right up. Remove jumper, install another relay and good to go. I have used repeatedly the same 3 relays, the contacts between terminals 30 & 87 appear to have some oxidation which I will remove, but have continuity, Two of the relays are of the old metal case variety and one is a new black plastic case type. The relays are not inordinately hot to the touch nor is there any burning smell.
I am beginning to wonder if I am seeing a symptom of impending LH failure here. The fuel pumps are both @ 2.5 years old. Other than this, the engine is running very well. Anyone else out there have any BTDT experience with this kind of problem?
I am beginning to wonder if I am seeing a symptom of impending LH failure here. The fuel pumps are both @ 2.5 years old. Other than this, the engine is running very well. Anyone else out there have any BTDT experience with this kind of problem?
Your problem sounds like my LH failure. The LH supplies the ground to the FP relay coil to energize it. At first, it can be so intermittent that replacing the relay seems to fix it, but it's mostly a coincidence. Often this will get worse and worse until it'll hardly work at all. You can try another LH for a few days/weeks to check it.
