NapalmZen

1993 civic cx with 1994 integra ls engine to a 1997 ls short block. (obd1 peripherals on an obd2 block)

had a new sub put in. a week and a half later my fuel pump gave out.

took it to the mechanic and i received these diagrams.





i have seen ,while poking around, a few posts about problems like this being related to an audio install.

i replaced the fuel pump and when that didnt fix it i bench tested the oem and it was functional. i wired in a toggle to my fuel pump from the battery and the car now runs and drives. any advice or diagnostics you could help me with would be appreciated.

mk378

Take the main (fuel pump) relay out of the car, take it apart and resolder. This is a very common problem in 1988-1995 models. The relays crack inside but can be repaired. There are directions all over the place since it is such a common problem.

NapalmZen

relay was tested as good if i understand. there is no power going to it from the fuse 18. fuse is fine, but has no power going to it.


we bench tested the relay. unless the contact has failed or arced and has a bad connection, it is fine. there is no solder fix just a replacement.

mk378

Fuse 18 is live only when the key is turned all the way to start, it is off when running. Power for the fuel pump comes in on pin 5 of the relay from another fuse. This should be hot in both run and start.

Yes the relays go intermittent, you really need to just resolder everything inside without looking or "bench testing" because that is inconclusive.

deschlong

iTrader: (8)

Yes it's an intermittent error so bench testing may give a false positive. Touch up the solder joints.

NapalmZen

thanks guys. ill give it a try and be back after testing.

would this also cause the lack of power to the ecu from the main relay?

mk378

Yes the pin 1 to pin 3 circuit does that. Pin 1 should be live all the time. Pin 3 should go live when you turn the key on.

Your picture shows it is factory solder, and it looks bad. The black rings around the pins are cracks.

deschlong

iTrader: (8)

^ Did you test this connection when the wire is hot? As in, during "START" (and not just "ON" )? You have to test it while the engine is cranking.

NapalmZen

i dont know how the shop tested it. i tested it in run.

i also pulled the relays and jumped the connections in both run and start. this is after replacing the pump.

EDIT: i currently have the power to the pump jumped with a single connector to the positive terminal on the pump to the battery with a 20 amp fused toggle. car runs and drives fine atm. i just dont like ghetto fixes.

deschlong

iTrader: (8)

Neither do I. Touch up those solder joints (ALL of them, to be sure), undo ghetto rig, test relay as normal, get back to us. Should fix it. If not we delve deeper.

Former User

USDM Civic? If so, test fuses 24 and 31.

NapalmZen

i checked every fuse in the car with a continuity tester. under dash and hood.

EDIT: well, the soldering is done. ill go plug it in in about 15 minutes. after the solder cools.

deschlong

iTrader: (8)

We await results with bated breath ...........................

NapalmZen

nothing. is sucked the last of the fuel from the system and died.

Former User

Specifically voltage test fuses 24 and 31.

https://honda-tech.com/honda-civic-d...fuses-3079359/

NapalmZen

with the car running?

Former User

With key in ON(II).

Does the engine start and run?

NapalmZen

yes. i have the fuel pump bypassed to a fused switch.

tested and both fuses are putting out around 12.3v on both terminals.

Former User

Good.

Now test whether voltage reaches the two respective pins in the unplugged main relay connector.

How do you have the main relay bypassed to run the fuel pump?

NapalmZen

clamped to positive battery terminal to a fuse to a switch.








which pins 5/7?


EDIT: sorry if im taking a while. i was making lunch and helping a neighbor push his car up hill.

Former User

Test main relay connector pins 1 and 5 for voltage with key in ON(II).

mk378

Pin 1 hot all the time
Pin 5 hot with key on-- this is from the fuse
Pin 3 hot with key on-- this is from pin 1 through the top section of the relay
Pin 7 hot for 2 seconds after key turned on (unless engine is running, then it stays on)-- this is from pin 5 through the bottom section of the relay. The ECU controls the relay by grounding pin 8 while the fuel pump should run, and removing the ground to stop it if the engine stalls.

NapalmZen

1 and 5 have power

everything else is dead.

EDIT: the relay was not connected. i could plug it in and test them all again.

EDIT2: everybody likes car ****. my GSR donor car next to my Civic Integra hybrid. cant wait to build my turbo v-tech.

mk378

Test with the relay plugged in.

Former User

The next test I recommend is to reconnect the main relay and then unplug ECU connector A.

Turn Key to ON(II).

Ground ECU pin A7 or A8, whichever one is connected to a Grn/Yel wire. Does the fuel pump run with A7 or A8 grounded?