I'm trying to get my JDM 1992 FD to pass an emissions test, and I found that the air pump relay was missing from the front fuse box.

After installing a new relay and idling the car, the air pump at first appeared to operates propely. It ran for a few minutes, but then blew out the 15 amp AC fuse (repeatedly).

I've quickly checked the wires near the Air pump relay box, and near the air pump itself, and there are no apparent issues.

I'd imagine that a short in the wire would blow out the fuse immediately. Since the relay was missing, it`s obvious that the previous owner wanted a quick fix for the problem ( and didn`t need to emissions test the car)

I suspect that it's the air pump clutch drawing too much current, or perhaps a short somewhere in the wiring harness.


Has anybody ever had this issue before?


Any tips would be very appreciated before I spend a lot more time and money on this car...


Thanks,

Demetree

 

I would double check the wires going to the airpump, they are rather close to the turbo's and get brittle. I had my wires snap in two when I tried to unplug it.

 

Yea, I would double check the wires too. With the power off, use a multimeter and test for continuity between the wires going to the airpump. Jiggle them around while you do. If at any point there's continuity, you've got a short. My wiring had this exact same problem, it would short out but only in certain positions.

It seems unlikely to me that the magnetic clutch is drawing too much current. It's a solid state coil and completely isolated in a plastic/rubberized coating.

 

Thanks for the great suggestions!

I will definitely test continuity with the power off, while jiggling the wiring. That's a great idea that seems obvious now that I think about it, but I never would have thought of it.

Beers on me

 

I've tested the circuits, and here's what I've found:

1. There is no continuity between the + and - pins of the air pump harness, even when jiggling all the harnesses around. I also installed a new fuse.

2.) There is continuity between the + pin on the harness, and the pin in the relay box

3.) There is a problem with the - pin on the harness and the ground pin in the relay box. When I test continuity there, I get a very short beep indicating continiuty, then the beep stops and the display of the multimeter says 486.


My theory is that there is a bad ground in the car.

Does anybody have any thoughts?

Thanks,

Demetree

 

I understood that when those airpumps go bad the blow the fuse.. replace the air pump with a good unit and no more fuse issue...

 

I spent some more time troubleshooting the air pump today, and I rechecked all the wiring. I couldn't find any problems anywhere in the wiring.

I built a simple circuit with a 20 amp fuse (spec is 15 amp) to test the air pump with while the car was running. The 20 amp fuse blew in about 15 seconds when the motor was running.

So how much does a new air pump cost, and does anybody have one for sale?