NEED HELP QUICK

[GTDrifter]

A friend of mine and I just pretty much completed an auto to manual swap (including swapping out full harness from engine to trunk) and the fuel pump is not working...currently going through the tedious process of positively identifying each plug and what it goes to (with help of a very technical wiring diagram)

The car does crank and all but there is no power to the ecu or the fuel pump. any help would be absolutely amazing...its been about a week of trying to figure it out

We did notice that some wires have been either cut, or cut and spliced back together for some reason (wires from a red relay which i cant remember what its for, wires near the ecu have been cut and spliced back together)


if its a repost i apologize but please post a link to the answer or just post the answer anyway

[SubaRooNZ]

hey pal what have you done?have u changed engine nd gearbox or just gearbox also what year car did this come out from nd what are u putting it into i had similar probs with mine had to redo loom for fuel pump relay

[GTDrifter]

he had a 95 impreza auto...he bought a wrecked 97 impreza manual...we stripped the 97 down to bare shell and then took the engine, transmission, rear drivetrain, and all the wiring and interrior pieces out of the 95 and replaced them with the 97 items. he replaced the relay with 3 brand new ones, replaced the fuses, we went over all the wiring like 3 times (each and every plug)

what do you mean redo the loom for the fuel pump relay?

[Huffer]

The car does crank and all but there is no power to the ecu or the fuel pump.

We did notice that some wires have been either cut, or cut and spliced back together for some reason (wires from a red relay which i cant remember what its for, wires near the ecu have been cut and spliced back together)

It's really hard to be able to help - you're going to have to be more detailed and go slower. You're tired, frustrated I'm sure!

If the ECU isn't getting power, then that's where I'd start first.

If the harnesses have been cut somewhere other than where you've cut, you're going to have to go back to those areas, strip the harness back and make sure all those lines have continuity and can hold current. You have to go by process of elimination.

[GTDrifter]

sorry for not being very clear...we didnt cut anything on the harness...we removed harnesses from both cars and put the 97 stuff into the 95. my friend said the 97 did not run when he got it because it hit head first into a pole and the camshaft pulley was destroyed but the rest of the motor was ok other than the radiator, fans, stuff like that.

there is a thick red wire with a yellow stripe going to the ecu that was cut and spliced to a smaller wire with the same color concept from the ecu...idk what that wire is for but thats the only wire that was messed up from the ecu (red is usually positive power wire right)

the car tries to start but theres no gas coming from the fuel pump for it to start...dash lights and all turn on but when he connects the obd2 scanner to the car theres no contact with the ecu


weve been trying to find all the wires that go to the fuel pump but its not the quickest and easiest thing to do

[Huffer]

When you turn the key, can you hear the fuel pump prime?

[02_Legacy]

What I would do is bypass the relay. Jumper the relay from the power in to power out to the fuel pump. If the pump turns on your problem is in the control circuit, if the pump does not turn on then the problem is in your main circuit.
I was taught that when you are dealing with electrical problems you should always try to keep cutting your problem area in half untill you narrow in on the problem. That is what the above test is doing.

[GTDrifter]

When you turn the key, can you hear the fuel pump prime?
no

What I would do is bypass the relay. Jumper the relay from the power in to power out to the fuel pump. If the pump turns on your problem is in the control circuit, if the pump does not turn on then the problem is in your main circuit.
I was taught that when you are dealing with electrical problems you should always try to keep cutting your problem area in half untill you narrow in on the problem. That is what the above test is doing.
what is the control circuit and what is the main circuit? would the control circuit be the harness running to the pump and main circuit be the harness under the dash?

[02_Legacy]

The control circuit is the circuit that turns the relay on and off. In this case I believe it would go to the PCM. When the PCM grounds the wire that goes to the relay it energises the coil and closes the switch on the relay.
The main power circuit simply goes from the battery through the relay and on to the fuel pump. So just connect where it goes into the relay to where it goes out of the relay and see if the pump turns on.

[rougeben83]

Do these cars have one of those emergency fuel pump cutoff switches? They trigger in case of impact, shutting off power to the pump. You have to pull a lever/switch/button around the fuel pump area to reset it usually...just saying.

Get a multimeter and see if the ECU is getting power and turning on.

[GTDrifter]

he used a multimeter but idk what all he checked
if anyone can give a definite answer if a 95 or a 97 impreza has that fuel pump shut off...it shouldnt be the case though because were using the 95 fuel pump that worked perfectly fine before the swap

[GTDrifter]

so we found out what the problem was. we kept the wiring that went through the drivers fender because we thought it was the same and well...it wasn't so once we swapped that out for the one from the parts car it started right up. cars back together and on the street now.

[chuckthefuk]

Did you keep the 97' ECU for the swap or are you using the 95?

OK lets bench test the fuel pump.

1) take the pump out of the sending unit.
2) take the pump to the battery at the front
3) put two thin wires in the connector of the pump
4) touch the +/- terminals on the battery.
5) the pump should start to whine.
6) only test this for a split second.. air is not a good idea....

...

If the pump is good reconnect it to the sending unit and test if the fuel lines are good.
1) Disconnect the fuel line from the fuel filter and crank the car.
2) If fuel comes out then its not the pump. if no fuel comes out the its the pump / filter / lines.

[GTDrifter]

we used the 97 ecu, complete front to back wiring, etc...we initially thought that the 95 automatic wiring through the drivers fender was ok to use but is apparently different from the 97 manual wiring...we tried even using the 95 ecu but that itself didnt fix the problem so were using all the manual transmission wiring and junk.

car is completely put back together and my friend has been zooming around town with it. just needs an alignment to say its 100% complete.

Lesson learned from this, when doing an auto to manual transmission swap you must change out ALL of the wiring up front.