fuel pump wont prime?????????????????

[1990 sr hatch]

so the other day i found out my fuel pump wouldnt prime. so i checked interior/ under hood fuses, the 10 amp fuel pump fuse was blown. so i replaced it, and my electric fans turn on that is wired correctly to the egi pump relay. checked all fuses/ relays, unhooked the fans. still nothing. then i wiped out the ole votmeter and the brown engine harness plug for the sr has a b/pink wire has no power. the w/purple wire out of fuel sending unit has no power. i tried explaining this as thorough as possible any help would be greatly appreciate

[Silentoreo34]

Check your relays. Try just running a wire to bypass the relay and see if that works and/or try to prime the car and listen for the relays click. If that doesn't work check for breaks in the wiring I had the same problem happen to have a broken wire.

[1990 sr hatch]

checked relays, how would i bypass the relay?

[1990 sr hatch]

anybody hace any ideas?

[cotbu]

Your not searching!
That's the problem with youths today! They want medals for participating!

[1990 sr hatch]

checked all fuses checked all relays, checked with voltmeter power in/out of pump?????????

[Silentoreo34]

checked relays, how would i bypass the relay?

Take a piece of wire and you connect the circuit.

[1990 sr hatch]

k so i just took the voltmeter to pin 104 ecu e5 and it gets full power with ecu unplugged, and full power with ecu plugged in, so im guessin somethin in the ecu must be fried if its not sending the power to fuel pump idk???? suggestions please

[Nub]

This is going to sound stupid but passenger side underhood relay box. shake it and the wiring. Then go start it. I don't know why but some of the wiring shorts out sometimes. Happened on mine and a friends. If that works to start it locate the short. and fix.

[Silentoreo34]

k so i just took the voltmeter to pin 104 ecu e5 and it gets full power with ecu unplugged, and full power with ecu plugged in, so im guessin somethin in the ecu must be fried if its not sending the power to fuel pump idk???? suggestions please

Check the fuel pump wiring in the back. Also look up the pinout and try to jump the fuel pump to make sure the fuel pump is working.

[1990 sr hatch]

fuel pump has never been used and i already tested it works fine with 12v source. and i havent deloomed the harness i wanna check, does the fuel pump harness run passed tail lights to driver side to under dash then across dash to were the ecu would be. usdm chassis btw

[!Zar!]

Bad ECU from the sounds of it.

[cotbu]

Pin 104 is a ground trigger, it's not supposed to see battery voltage! It's probably being shorted. pull the negative ground lead off the battery and remove the ECU. Inspect the ecu for any burnt traces. With the battery still disconnected, check continuity on the wire for 104, to ground and adjacent wires.( take note) Rre-connect the battery only, test the 104 wire for voltage, and any wire it had continuity with. Then isolate the 104 wire from anything that was giving it voltage. Repair or replace the ecu! That may not be chronological, but you should be able to decipher what I want you too do. If not tell you wiring guy, I said "wassup!"

[1990 sr hatch]

k so i disconected the negative lead, and removed ecu. My voltmeter is set to ohms, and it beeps when connected to pin 104, and grounded. now whith the negative terminal connected and key set at 0/lock theres no power. now with key set to 3/on it reads 12volts, whats this mean? thanks for your help

[cotbu]

Originally Posted by 1990 sr hatch

whats this mean?

You have f'd up wiring! Or a 12v ign short! With the 104 wire reading 12v start pulling fuses, everything except the 75amp main fuse, hopefully you find the circuit that way. It could be right under the relay or in the harness. You could run a parallel wire from the relay to pin 104, but you'll still have a short, but then your car would only be half broken!

PS you did examine the ecu for burnt traces? its usually a side effect of sending 12v down the trigger wire. If the wire doesn't burn or fuses don't pop.

Sent from my Highly Tuned Vibrant!!

[KiLLeR2001]

How are your fans wired up exactly?

[MrSanchez925]

pull out a schematic and start diagnosing.

[1990 sr hatch]

i probaby should have said this earlier but the EGI relay has continuity with #3and#5 pin on the relay with negative terminal off. and the same #3and #5 pins read 12volts with negative terminal connected. does this mean any thing?

also whish relay/ wire would i run to pin 104?
thanks again with all your help

[cotbu]

Yeah your fans! That's a no no!

Should be the one you were testing!
With the relay removed and looking down into the socket. Pin1

[1]   [2]
 [3] [4]

Sent from my Highly Tuned Vibrant!!

[1990 sr hatch]

my fans have negative grounded, and positive wired to #3 EGI pump relay, and fans work when key set to on

[1990 sr hatch]

pin #1 reads 1.8 to 1.9 volts im guessin that aint good

[KiLLeR2001]

Dude... You can't power fans off of one dinky ass 18 gauge wire from the the EGI relay and not expect to mess things up...

This topic has been discussed thoroughly.

[1990 sr hatch]

okay clearly i F'd up, how coud i fix it ?

[1990 sr hatch]

Originally Posted by cotbu

You have f'd up wiring! Or a 12v ign short! With the 104 wire reading 12v start pulling fuses, everything except the 75amp main fuse, hopefully you find the circuit that way. It could be right under the relay or in the harness. You could run a parallel wire from the relay to pin 104, but you'll still have a short, but then your car would only be half broken!

PS you did examine the ecu for burnt traces? its usually a side effect of sending 12v down the trigger wire. If the wire doesn't burn or fuses don't pop.

Sent from my Highly Tuned Vibrant!!

yeah i pulled the ecu cover off nothing seemed burnt or smelled burnt

[marvlrose]

I am having a similar issue. I am doing a VH swap and on first try the fuel pump primed in acc but once key turned to start there was nothing. After that one time I have been unable to get the fuel pump to prime in acc, I have taken the pump out and tested it with no problems. I am going try bypassing the relay tomorrow and see how that works.

[1990 sr hatch]

(marvlose) i figure i have a short some where cause the fuel pump turns on randomly lol. just go over you fuel pump wiring, its a pita but it will hopefuly solve your problem
p.s. id like to see your vh swap please

[S-Nation S13]

Originally Posted by 1990 sr hatch

(marvlose) i figure i have a short some where cause the fuel pump turns on randomly lol. just go over you fuel pump wiring, its a pita but it will hopefuly solve your problem
p.s. id like to see your vh swap please

Your so lucky it was just a short, my fucking ecu fried what are the odds of that bullshit...but anyways im glad you figured it out. Ive seen a trend recently that these damn fuel problems come and go, but it is safe to power the fuel pump directly? And run if off that ?

[marvlrose]

So I bypassed the relay today and had no luck. I took off the covers of the ecu to check for burn marks on the board and saw none, checked the pins too. I am going to pull the pump out and do some jimmy rig testing this weekend to see if maybe there is an issue in the harness or something. The harness could def be an issue since the guy who had the car before me put in an aftermarket pump. (1990 sr hatch) I will post pics of the car this weekend when I get back from MN.

[1990 sr hatch]

yeah i dont get how it shorted just glad i found it lol, and marvlose i love seein pics of fortys beeters or not just love em lol

[marvlrose]

So I managed to fix my problem. After a long day of diagnostics I found out that somewhere a long the harness from the fuel pump realy to the fuel pump the blk/yel wire lost continuity. Instead of digging and trying to find the wire in all that harness I will just run a new wire from the output on the relay to my fuel pump, hate to do it that way but I am glad it isnt my ECU lol. having issues uploading my pics but I will try to have them posted within the week for ya 1990 sr hatch.