10 Amp Engine fuse on an 89 FI

[gunnerw]

Dale I benched tested the relay as you suggested. The wires on the pig tail didn't match the colors that you listed but the wires in the connector that plugs to pig tail did. When i connected blk/wht to 12+ and blk to 12- the relay does click. When I checked continuity between the other two terminals, I only had continuity when the blk/wht and blk terminals are connected to the battery. Does that make sense

[dalebwilson]

Yes. That means the coil is good and the relay is functioning properly. Now check to see if you have continuity between any of the wires to the metal case of the relay.


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[gunnerw]

I just checked each terminal to the metal case. None of them have continuity.

[dalebwilson]

That's good. Your relay appears to be good. With a new 10amp fuse installed and the key off, check continuity on the black/white wire to ground. Then check the black wire to ground.


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[gunnerw]

Yes to both. new 10a fuse and blk/wht at connector to ground and blk wire to ground. both have continuity

[dalebwilson]

Remove the 10amp fuse and check blk/white to ground.


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[gunnerw]

I just checked the blk/wht with the fuse out. No continuity.

[dalebwilson]

In my opinion the 10amp engine circuit should not have continuity to ground. It could however be reading through other circuits, lights, coils etc. Has your wiring been modifed at all by the previous owner? Could you have any extra load put on the engine fuse? Try this temporarily to see if your engine will run.

Remove 10amp factory fuse and resinstall the relay. Install a 12V+ wire with inline 10amp fuse from the battery and temporarily splice to the black/white wire. Crank engine and determine if it will stay running. Remove temporary setup immediately when test is complete.

[gunnerw]

Are you confidant the bench test I did proved that the relay is good?

[gunnerw]

I can check with the previous owner. I did notice one location where two wires were spliced into one with electrical tape but dont remember any wire colors. I'll check that when i get home. What other devices run through the engine fuse? I just installed a new fuel relay and fuel pump do you thing that could be it? It was a pretty straightforward process to install both.

[dalebwilson]

According to what you told me, the main relay appears functional. Per the Haynes diagram, the engine fuse only supplies power to the main relay.

[gunnerw]

I have looked around the engine for unusual wiring changes. The photo shows two modifications that I can see. One wire yellow/green cut at on time and the re-crimped. The other is a black/white wire coming from the wire harness just under the wiper motor and is spliced in to a smaller black wire that goes to the connector under the ignition coil. Then the black/white wire travels to a connector into a smaller wire (same size as the wire under the ignition coil) that lead to a small square box on top of the distributor. I looks to me like both small black wire were at one time the same wire that would have run from the distributor to the coil. That would be my guess. Any ideas?image.jpg

[dalebwilson]

Be cautious that Blk/white is the same wire color of the "Engine" circuit. Did you ever do the test with the alternative 12V supply?

[gunnerw]

I havnt done the test yet but I will before I do anything else.

[gunnerw]

Dale,

I tried the test you suggested. I ran a wire with a inline 10a fuse from the blk/wht wire to the 12+ on the battery. As soon as I connected to the battery i could hear the main relay click. I cranked the car but it would not start. I tried this a couple of times. I had a friend with me and to demo the problem to him is removed the temporary wiring and put a new fuse in the engine slot on the fuse box. As soon as i cranked the engine it started and ran for about 1 minute then died. We both did smell something burning. No flames or smoke the the slight smell of smoke. The only non standard equipment in the car is a radio that was added years ago..

Any new suggestions?