i was working on my car yesterday trying to get my cel codes off, which has nothing to do with the fuel pump, and out of nowhere it wont prime anymore. so i ran a direct power wire to the fuel pump and the pump isnt bad, i even tried putting the stock one back in for the hell of it and it still wont prime. the car also wont start when theres direct power to the pump. ive checked the fuel pump fuse under the dash and its still good, i even replaced it anyway. i dont know where else to look. i have a 97 civic dx, and the only other thing i can think would be the main relay but i dont even know what it looks like, or where it is.

other than the main relay is there anything else that could be causing this?

 

have you tried tracking the wires back to the fuse box.
or put 12 volts to the pump directly and see if the fuse reads it.
sounds like a short but im sure some one else has another idea

 

its hard to track the wires and check them, but i ran wires from the fuel pump to the ecu, wouldnt prime. ran wires from the ecu to the fuse, wouldnt prime. and when i run a wire from the fuse to the pump, itll turn on but the car still wont start. it sounds like a bad main relay cuz from what ive read that also controls the injectors and a few other things. but idk where it is

 

main relay, its under the dash

 

wow. that was helpful. could u narrow it down a little bit? specifically where under the dash

 

nvm i did some research and located it.

 

could a bad main relay cause it not to start with the key?

 

yep... if you have a paper clip you can force the pump to prime. check a haynes or helms manual to see which terminals you need to jump.

on a side note. have you checked ALL your fuses before you start messing with wires and relays?

 

no. what other fuses deal with the fuel pump priming other that the fuel pump fuse and the main relay?

im working right now, i work at a parts store and ive got a brand new main relay sitting in front of me, im just waiting to get home and put it in.

 

when it comes down to electrical mysteries like this its best to pull every single fuse (engine bay and interior) and inspect. and tapin it with a voltmeter doesnt always cut it cuz you could get false reading sometimes

 

Check hood fuse 44 and dash fuses 31 and 13. The main relay is to the right of the glove box.

Also check whether the G101 ground wire attached to the thermostat housing is clean and tight.

What CEL codes are being thrown?

 

im not sure of what codes its throwing now. before the fuel pump stopped priming it was throwing an IACv code which im not worried about(im doing the 3-wire to 2-wire IACv fix) and with the obd2 ecu thats now the only code its throwing.

i will check those fuses tho, thanks

 

also theres a symptom i forgot to mention... normally when you turn the key, the fuel pump primes and the cel light goes off when its done. well now that its not priming, the cel never goes off.

is this another symptom of a bad main relay?

 

ttt?

 

fuse 44 was blown. THANKS!

i tried the new main relay anyway just to see if thats why it wouldnt start with the key and that didnt work. so it still wont start with the key.

ignition cylinder?

 

err i mean... lock cylinder, key tumbler, whatever its called

 

Any resolution to your problem?

 

bad main relay's go out in hot weather. re-solder the connections. takes 5 minutes