Hot Shut down

JBC · JBC's Garage

Okay, now that I have my coolant system understood I have a new issue. I think I'm
'peeling back the onion" from this car sitting for almost 10 years.

After a long while running, the car warms up and then shuts down. It is a fuel issue because I can jumper the fuel/DME relay and the pumps runs continuously and the car will start. Without the jumpering of the relay, I have to wait about 30 minutes and then the car will start.

Pulled the relay and did a continuity check and checked the operation of the relays at the same time - no problems. The relay works fine.

What else could cause a hot soak shut down of the fuel?

JBC

Techno Duck · Techno Duck's Garage

I would suspect the DME relay is faulty when hot; especially because you can jumper the fuel pump and the car restarts. This is a fairly common issue.

AaronM · 12-17-2014, 01:42 PM

Quote:

Originally Posted by Techno Duck

I would suspect the DME relay is faulty when hot; especially because you can jumper the fuel pump and the car restarts. This is a fairly common issue.

I'm seconding this. It's pretty common for the relays to check out OK when cool but get flaky when hot.

JBC · JBC's Garage

I would agree except for the test I ran. I hit the relay with a heat gun while it was out of the black plastic housing. It still tested good. So, even when I heated up the relay it tested fine. I did notice that the relay was warm when I pulled it to place the jumper. You would think that after heating up the relay with a heat gun, I'd see the failure but I did not. Makes me suspect the actual fuse panel itself.

Bradical · 12-17-2014, 07:21 PM

The fuse panel has no moving parts, where the contacts in the relay AND the coil could both be cause for issue. What would heat have to do with a bunch of terminals? Just my $.02

JBC · JBC's Garage

Quote:

Originally Posted by Bradical

The fuse panel has no moving parts, where the contacts in the relay AND the coil could both be cause for issue. What would heat have to do with a bunch of terminals? Just my $.02

Good point but I'm not sure if heat would impact the actual relay/fuse panel or not. I don't know how it is constructed. I'm not overall impressed with the construction of the relay panel nor its location.

Jumpering the relay to allow the fuel pump to continuously run, starts the car and keeps it running. That would eliminate the coil but I will test the coil more accurately now. My testing of the relay removed from the car, in both hot and cold conditions, did not replicate a relay problem. However, I have seen the relay fail on my bench before without identifying the failure. One relay worked and the other did not. I did replaced the diode. I guess I could have some crack in the board or something about the terminal that is causing an issue and it is triggered by the position of the relay in the terminal more than temperature. I guess I will have buy a new relay and see what happens.