hey i was trying to diagnose my integras fuel pump problem and i need to know if the p75 ecu from a 1994 integra ls 5 speed non vtec will work on my 1992 integra ls 5 speed non vtec.

 

Yes, they are both OBD1 ecus so it will work fine.

 

ok thanks a lot, hopefully this fixes my tegs pump priming problem, main relay and new pump didnt solve it=/
im gonnna try the ecu and hopefully get her back on the road

 

Before you get the new ECU try a couple things if you have not already.

Make sure all 3 fuses for PGM-FI Main Relay are good...

Fuse 24-15A, [hot in start and run] in under dash fuse box.
This is the black/yellow lead at relay, injector relay control, [coil] and fuel pump power.

Fuse 18-7.5A, [hot in start, (cranking) only] in under dash fuse box.
This is the blue/white lead at relay, "back-up" power for fuel pump relays coil.

Fuse 38-10A, [hot at all times] in engine bay fuse box.
This is the yellow/white lead at relay, input power for fuel injector relay.

Make sure not only that the fuses are good but also that those powers are at the PGM-FI Main Relay, if they are, turn ign. on to run, [not start] and test for power on the yellow/black, [fuel injector relay output]

If all the above is good use a jumper lead to supply a ground to the green/black lead/terminal at the PGM-FI Main Relay, [fuel pump relay control from ECU/ECM.

If fuel pump runs then the problem is no ECU/ECM ground out for fuel pump relay control.

But before you swap out the ECU/ECM check and make sure there is power on IGP1 and IGP2 at ECU/ECM when ign. switch is on, they are the only two yellow/black leads on the ECU/ECM, both IGP1&2 need power before ECU/ECM will supply the ground control for the fuel pump relay. 94

 

i checked my connections and im not getting current through the blue/white or the yellow/black which is power to the pump at the relay. the fuses are all good and fuse tester showed they were passing current.

i was in the car yesterday and i turned the key and heard the pump so i turned it on. i let the car warm up (to charge my battery a little) then turned it off. the car had not wanted to turn on for two days. (i would turn the key to hear if pump would prime and check engine light would turn off.) when it actually primed the pump yesterday i tuned the car on for maybe half an hour turned the car off and turned the key to on so i could listen to the pump. i did that like 5 times and pump primes check engine light would turn off. then on the next try pump wouldnt prime and check engine light stayed on.

this all seems like the ecu because the car was not moving and i didnt mess with any cables so i dont believe theres a bad connection. the car did have the infamous cowl leak when i bought it so it makes me think maybe water could have gotten to ecu.

 

The blue/white will only have power when cranking to start.

The yellow/black is not fuel pump power, it is the output of the fuel injector relay, it powers the injectors, a few engine valve/solenoids and signal to ECU/ECM, it should have power when ign. switch is on, [run and start].

The black/yellow is power for the fuel pump, [input power for fuel pump relay] and injector relay control, [relays coil].

If you have no power on the yellow/black when ign. switch is on, the injector relay is not turning on, make sure there is power on the black/yellow. [ign. on, run and start] and that the PGM-FI Main Relay is grounded, [black lead(s)].

 

i used a multimeter and the black/yellow isnt getting any current. the 3 grounds to the relay are good and getting current. all fuses are good too. the ecu is what provides power to the relay right? the car would sometimes start up after sitting for a while, but so far its been 5 days and the cars pump does not prime. the CEL will not turn off. i havent moved the car or any cables so i dont believe its a loose cable connection. i had somebody from a honda tuning shop look at it and he told me the only things it could be was the ecu or a bad cable and the bad connection is before the relay because it wont pass power to the pump. (i barely replaced fuel pump, relay and fuel filter) so far im convinced its the ecu, i looked at all the grounds and they are good.

 

it turns out the ecu was the problem, my integra is a 92 ls which was p75... but the ecu it came with was pr4 and i found out the pr4 is for years 90-91 only. i bought an ecu for 65 and as soon as i popped it in, the car turned on no problem and has been running great since then. thanks for all the help, i finally got my teggy back on the streets

 

That is wrong, all the LS ecus in the 1990-1993 Integras where marked PR4. After they changed the body style they started marking them P75 and that is for the 1994-2001 Integras. However, OBD1 Integras are 1992-1995. Might just be the ecu did go bad but glad to hear it's working right.