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Nate,
You could have a relay getting hot and consequently not working. Based on the history, let everything cool down, put the relays back in their original slots, and try to start it at lunch time. If it starts, great! When you get ready to drive home, prop your fuse /relay wooden cover open to that more air can get to the relays and cool them. Use an IR thermometer (if you have one) to determine which relay is getting too hot and then figure out why it's getting too hot. Good Luck!
Good advice. I imagine it could only be one of 3 relays if it was a relay issue correct? The starter, the fuel pump and the fuel injection relay. Even if I pulled all of the other relays it would still run, but those 3 are the only ones I can think of that would prevent it from running. Or am I missing one?
I've been meaning to get an IR temp gun for a while. Now's a good excuse.
I did wiggle the fuse pump fuse in is socket and it felt secure, but it wouldn't hurt to increase the tension on the clips. I do hear the fuel pump running when I turn the key to the "ON" position. I guess in theory it could cut out when it's trying to start. I'll have one of my co-workers crank it while I listen from the rear.
Good advice. I imagine it could only be one of 3 relays if it was a relay issue correct? The starter, the fuel pump and the fuel injection relay. Even if I pulled all of the other relays it would still run, but those 3 are the only ones I can think of that would prevent it from running. Or am I missing one?
I've been meaning to get an IR temp gun for a while. Now's a good excuse.
Those would be ones that I would check first.
You should never NEED a good excuse for getting another tool. Just wanting one should be a good enough reason.
So I think I found the culprit! Fuel Injection Relay. Just went out at lunch and it started right up. I swapped in the horn relay and it wouldn't start. Put the FI relay back in and it started. So the horn relay is definitely is not a replacement for the FI relay. At least not on a US 1984 model. Then I put the FI relay in the horn socket and the horn worked. That wasn't the case this morning right after it died. So hopefully it's just a bad relay and not something upstream of the relay causing it to overheat and fail. I will be ordering a new relay and see if that resolves it.
Here are some picks of the FI relay with the cover off. To my untrained eye I don't see any obvious defects. Anybody else see something that might be amiss?
Apologies for the bad info, Nate- the day you were stuck I pulled the '84 wiring diagram and to my lower primate eyes the schematics for relays XVII, XIV, XXI and XXII all look electrically the same, but I guess they are not. I have read that the '84 wiring diagrams are a bit of a mess, clearly I don't have much experience with them.
Apologies for the bad info, Nate- the day you were stuck I pulled the '84 wiring diagram and to my lower primate eyes the schematics for relays XVII, XIV, XXI and XXII all look electrically the same, but I guess they are not. I have read that the '84 wiring diagrams are a bit of a mess, clearly I don't have much experience with them.
No need for apologies at all Rob. In fact if you hadn't suggested to swap them I wouldn't have thought to try the FI in the horn socket. The fact that the horn didn't work with the FI relay after it died but did a few hours later confirmed that the FI relay is the issue. And now I'm just hoping that there is nothing upstream that was causing the FI to malfunction and that it's just the case of a bad relay. The cover does have Made in W-Germany on it, so it may be the original relay, or at least pretty old.
Hey Nate, I was going to correct the statement that you can use another relay in place of the FI relay in the '83-'84 Sharks but forgot. I have a '83 and a '84, the Fuel Injection Relay is unique and the only relay that will work. I had to replace it in my '84. Made all the difference. Car runs great now. They are not that expensive. Probably best to buy two and have a spare.
Regards,
Joe
PS You usually can't tell if a relay is bad by looks alone. They can look so good and be so bad!
Nate, same problem on the 82. The “dead” relay would let the car start, but die after a few seconds. It looked new inside and out. Replaced with a used one from my spares bin, and she fired right up....weird mojo in them thar relays....
So on my way home yesterday I drove it with the FI relay cap off to help keep it cool. Also decided to mount a GoPro to film it while I drove should it breakdown again. Well it did and less than a mile from my office on the way home. It's definitely the FI relay. Check out this video (sorry for the blurriness). At the 9 sec mark you will see the contact tab release. Car immediately dies. I was able to drive it home after wedging in a thin piece of plastic to get the contact to engage. Roger has two relays coming my way.
Yup, I keep 2 new spares in the trunk tool box along with the switched jumper. Its the only on-road failure I've had, twice now with 2 different relays. First was at a gas station 2 hours from home and the other was at the end of my driveway after an extended wide open throttle pass of my wife in her 997 on the long straightaway of the state highway before our neighborhood turn off.
So on my way home yesterday I drove it with the FI relay cap off to help keep it cool. Also decided to mount a GoPro to film it while I drove should it breakdown again. Well it did and less than a mile from my office on the way home. It's definitely the FI relay. Check out this video (sorry for the blurriness). At the 0.09 sec mark you will see the contact tab release. Car immediately dies. I was able to drive it home after wedging in a thin piece of plastic to get the contact to engage. Roger has two relays coming my way.
Hi Nate...
Clever way to monitor that relay!
Check this link for some more info on the fuel pump relay. See post 6 and 7. If I understand correctly, the FP relay gets its power from the ignition circuit (key position 1, relay terminal 15), ground through terminal 31, and control via 31b. When the key is turned to position1, the relay closes the contacts for a second or two. After that, it relies on a signal from the ignition module on 31b that tells it whether the engine is cranking/running. I think it connects to the module terminal that tells the coil to fire (and probably runs the tach). If that signal goes away, the FP relay opens and stops the fuel pump.
Since that's an electronic circuit inside the relay, it can (and apparently often does) fail and replacing the relay solves the problem. If a new relay doesn't solve the problem, then I think the next step is chasing down the signal to 31b. I think if you jumpered 30 and 87 and it still stalled, that would mean either the module stopped sending the coil firing voltage pulse, or the wiring between gains too much resistance over time or heat. At that point you could run a separate wire between the module and the relay which would prove/disprove that circuit.
05-17-2018, 01:47 PM
