1989 Honda Prelude FUEL PUMP / ALTERNATOR 10A FUSE

You're going to have to use the"process of elimination" here. Unplug the fuel pump relay and try a new fuse. If it blows again, disconnect the neg post of the battery and remove ALL the wires from the alternator. One of the alternator wires "the large one" is hot from the battery so be sure none of them is grounded. Then, reconnect the neg cable and try again. If it blows the fuse again with alt. disconnected and FP relay out. Get back to us and we'll go to plan "B", whatever that is.

James:
I used the "process of elimination" removed the fuel pump relay...the fuse did not blow.

I got a replacement fuel pump relay...pluged it in...the fuse blew.

What's wrong?

James:
An update...
I relocated the new fuel relay to its designated spot...no more fuse blowing...but
Still no action from the fuel pump.

Am i missing any additional fuse or relay that would keep the fuel pump from working?

Thanks...

If you jumper the wires to the fuel pump at the relay, does the pump run?

James:
See attached pictures / scan from the service manual.

The drawing of the fuel relay plug does not match the actual relay. So i don't know what to jump to get power to the fuel pump.

I can't tell if the pics downloaded...i can send them as a pdf.

Thanks...

No files came through. Our system only recognizes "jpeg" . The wires you want to jumper in the relay socket are both black w/yellow.

James:
I jumped the yellow /black and the black [the same colored wired going into the plug at the fuel pump] and i got power at the plug at the fuel pump [with a test light]. With definate power to the fuel pump...it doesn't work. So via the process of elimination i'm guessing the fuel pump is dead.

So, why... With the fuel relay plugged in, isthere no power to the fuel pump plug?

Thanks...

Well done my friend. I think you're dead on. Honda's , as a rule, aren't hard on fuel pumps.

James:
Update from the 89 honda prelude si guy...

I removed the fuel pump...gave it some time to dry out...attached power to it on the bench...it hums...not the whir sound i remember when i relplaced it around 10+ years ago.

Again, why is there no power to the fuel pump plug when the fuel relay is plugged in...there is only power when the relay is bypassed???
Does the relay sense that the pump is not plugged in and cut off the power?

That explains how the relay works and why [by myself] i couldn't put the test lught on fast enough to see if there was any power to the fuel pump with the relay plugged in.

Thanks again...89 prelude guy

There are 2 fuses that feed the "main/fuel pump" relay. #12 under the dash, which is apparently good if you made the pump him. And #38 under the hood that feeds the relay coil circuit. If # 38 is out, the relay won't pull in.
If you give me your email address, I'll send you a PDF of the diagram. I could attach it here, but because of the detail on the drawing, it won't come through very well.

thanks!!!

Let me know what you find, or if I can help further.

James:

New fuel pump in...starts like a champ.

Thank you!!!

I have one more ongoing problem...
Power to the gauges in the dash...tachometer, gas gauge, and temp gauge.

I've can live without the tach and the gas gauge ...i miss not knowing if the engine is getting too hot.[especially in the desert southwest summer.]

Is there any fuse or relay i'm missing or do i just need to to do the "trial and error" ...testing of each system / sensor.[how does that work w/ the tach?]

If i need to submit this as "a new question'
Let me know.

Thanks again!!!
Prelude si guy

I sent you some PDFs on the circuits for your dash panel and gauges. On the temp sensor there is only one wire to the sensor. With key on, ground the wire to the sensor. If it pegs the gauge, the sensor is bad. You can do the same with the fuel gauge. If neither gauge moves, there's a fuse your missing somewhere.