No start - fuel pump relay
10-22-2015, 08:42 PM
#1
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No start - fuel pump relay
Took my Spyder on a 3 hour trip Wednesday for business and it ran great on it and a couple short drives after (lunch, hotel, customer account, etc). Today after 2 more stops, I filled up at a Gas station, went to leave, and it would turn over very strong, but no sense of even a sputter or attempted firing. After a few tries, I figured it was time to pull the carpet, panel board, and check the fuel pump relay. Sure enough, that was the issue. The cover was melted, deformed, and no longer on top of the fuse or whatever the glass topped portion is (see pics). What's the brown goo on the edge of the fuse contact?
I swapped in the new fuel pump relay I had in the tool box in the trunk (thanks to this forum recommending a spare be carried) and the car fired right up and ran perfectly for the 3 hour return trip home. The new relay is a more standard looking one without the fuse on-top that I purchased a few months back from Mark & Tom. It came out of the blue box in the photos.
I'm wondering what caused the old relay to fail in this manner, or is that a normal failure mode) and if there is anything else I need to look at now that the car is back home (the fuel pumps themselves, fuses, etc). When putting the car together I installed all the proper amperage fuses into the slots based on the information from the owner's manual.
Incidentally, the fuse itself still passes a continuity test with my multi-meter, but fails the fuse holders contact to contact continuity test, which I find odd since those contacts touch both ends of the fuse. When attempting to take the fuse out of the relay holders, the glass fell apart. The fuse says BUSS GBC 16 on it. Could this relay work as a spare if I install a replacement 16 Amp fuse back between the contacts or is that not a good idea?
Thanks.
I swapped in the new fuel pump relay I had in the tool box in the trunk (thanks to this forum recommending a spare be carried) and the car fired right up and ran perfectly for the 3 hour return trip home. The new relay is a more standard looking one without the fuse on-top that I purchased a few months back from Mark & Tom. It came out of the blue box in the photos.
I'm wondering what caused the old relay to fail in this manner, or is that a normal failure mode) and if there is anything else I need to look at now that the car is back home (the fuel pumps themselves, fuses, etc). When putting the car together I installed all the proper amperage fuses into the slots based on the information from the owner's manual.
Incidentally, the fuse itself still passes a continuity test with my multi-meter, but fails the fuse holders contact to contact continuity test, which I find odd since those contacts touch both ends of the fuse. When attempting to take the fuse out of the relay holders, the glass fell apart. The fuse says BUSS GBC 16 on it. Could this relay work as a spare if I install a replacement 16 Amp fuse back between the contacts or is that not a good idea?
Thanks.
Last edited by Petza914; 10-22-2015 at 09:02 PM.
10-23-2015, 12:16 AM
#2
Chronic Tool Dropper
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I'll have to admit that I've never seen a fuel pump relay like that, with an external fuse.
From your description, something got pretty hot at the relay, hot enough to melt the potting out of the 'smart' part of the fuel pump relay anyway. That's either from contact resistance inside, or resistance it that external fuse and fuseholder. Might be interesting doing some forensics, or maybe just try a new fuse in it to see if that's what failed. But... Consider how much more inconvenient it would have been had the relay failed while you were on your way to your business appointment. Relate that to dollars and how much a known-good correct relay costs, and decide if the already-failed-and-stranded-me-once unit is worth the risk. My two sense.
From your description, something got pretty hot at the relay, hot enough to melt the potting out of the 'smart' part of the fuel pump relay anyway. That's either from contact resistance inside, or resistance it that external fuse and fuseholder. Might be interesting doing some forensics, or maybe just try a new fuse in it to see if that's what failed. But... Consider how much more inconvenient it would have been had the relay failed while you were on your way to your business appointment. Relate that to dollars and how much a known-good correct relay costs, and decide if the already-failed-and-stranded-me-once unit is worth the risk. My two sense.
10-23-2015, 07:31 AM
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I agree. I'm not going to mess around with something that could potentially start a fire next time and will buy a couple of spares to put back into the in-car parts kit.
10-23-2015, 07:37 AM
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10-23-2015, 12:55 PM
#5
Chronic Tool Dropper
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Pete, FWIW, the fuel pump relays are typically 75-100k parts service life in my experience. You may want to stock spares now for the time when they are NLA, but lightnoing seldom strikes so quickly in the same place.
Flip side of course is that Edsel Murphy, the patron saint of 'interesting' cars and owners, would tell you that the part you carry with you will never be needed, or will be wrong when it is needed, or will fail as soon as you have confidence that it won't. Then there's also Fig Newton's Third Law of Electrical Reciprocity, but it would be a stretch to think that it applies to your particular situation.
Flip side of course is that Edsel Murphy, the patron saint of 'interesting' cars and owners, would tell you that the part you carry with you will never be needed, or will be wrong when it is needed, or will fail as soon as you have confidence that it won't. Then there's also Fig Newton's Third Law of Electrical Reciprocity, but it would be a stretch to think that it applies to your particular situation.
