Fuel pump not getting any power

[916S14]

Hey i know there is a member on here that has the factory wiring diagram in their sig, just spent an hour looking for it. Anyone know this person or better yet tell me why my fuel pump isnt getting any power. Dont really want to start checking stuff until i get the wiring diagram. Thanks a lot! oh and the car is a 1989 coupe

[Z U L8R]

i have the wiring diagram in my brain @@

check the fuse first :|

but as far as wiring diagram you need to isolate the black/pink stripe wire that's in your reddish/brown plug.

the plug is right next to your battery tucked up in the fender. unplug it and grab the male end. you can check that your ecu gives it a 5 second ground when u turn the key on to prime your fuel pump. then when it senses your engine turning over (via the cam angle sensor built into the distributor) it gives it a constant ground.

on the female end it should have power when the key's turned on, if it doesn't then check your fuel pump fuse in the fuse block right by the passenger fender where you're already standing. it's a red 10 amp fuse. or you can just check the fuse first...........

Dave ^.-

[916S14]

I checked the fuse already. I'll do what you told me. But here's what i did last night since it took a crap on me right on the freeway, I opened the trunk and luckily i had an ohm meter. I unplugged the plug that goes straight into the fuel pump in the trunk and i think it was a whitish wire not getting any power. So i took some wire and hooked it up straight to my batter and left the car at my friends house. It get ground, just not power.

[916S14]

Update. So i changed out my fuel pump relay and car started right up. Drove home took a shower and try to start the car again and nothing, once again fuel pump not turning on. Too upset to go look at anything but looks like i'm blowing out relays left and right, could this be a bad ground or f'ed up wiring? Its a redtop SR.

[Z U L8R]

if your car's lowered, you might wanna check the wiring harness that's in the driver's side fender well area and see if it's rubbing the wires....

if you run out of ideas i'll tell you how to wire in your own fuel pump relay it's no biggie.

Dave =]

[ecuastyle84]

what fuel pump do you have?...how long have you had it?...might be a bad fuel pump and fuel filter....same thing happen to me where my fuel pump fuse kept blowing...replaced the fuel filter and fuel pump and it fixed my issue...hope this helps

[916S14]

hmmm fuel filter is a new 300zx one but the pump is a old sohc one. Its not my fuse thas blowing its my relay. I'll check the wiring harness and see if any of the wires are are exposed or damaged because my car is kinda low. Thanks, i'll update.

[916S14]

update. So i checked the harness under the wheel and in the bay and everything seems like its getting good ground. Fuel pump is a good one i checked it. I hear the relay click but it does not start and fuel pump wont turn on. Thinking its the ECU..... So anyone in sacramento want to let me try to use they're ecu for a sec to see if it will start? I'll pay for lunch and gas. =)

[Z U L8R]

go by your battery. unplug the little red plug tucked in the fender well. grab the male end of the plug and put your test light (which needs to be connected to your postive battery terminal) and probe the black/pink stripe wire. turn the key on and see if your test light will light up for the first 5 seconds then go out. if yes, now try cranking your motor. your test light should stay lit while you're cranking the motor. if it does both of these things, then your ecu's fine. and somewhere from your fuel pump relay to the fuel pump there's a break in the wire. you can either trace down the open , or run your own power wire from the relay to your pump. or i'll tell you how to wire in your own relay...just depends on how tired of this problem you are :D

test those 2 things and report back lol.

Dave =]

[Inland180]

where is the fuel pump relay located?

[downshift_sideways]

In your fuse box in your engine bay. Labelled "EGI" Relay.

[4bangers]

how do you know if your relay is blown? does it has a indicator like the fuse does? and where do you go get a new relay without ordering online.

I'm asking because I have this same problem last time and even my mechanic give up on my electrical problem.

[projectRDM]

In your fuse box in your engine bay. Labelled "EGI" Relay.

Close. 'EGI pump'. The EGI relay is just the power relay for the ECU.

[916S14]

alright update. I did what Z U L8R told me to do and everything checked out fine. Here's the thing i changed out the fuel pump fuse and the god damn car started right up and drove and still is driving. What i dont understand is why it worked with this new fuse when the old one is also good? they are the same amp and i know the old fuse is good because i put it in my friends 240 and it also ran. So could a fuse be like working at half capasity? or maybe just dirty or something? it was all clean though....
(http://www.zilvia.net/f/member.php?u=53770)

[916S14]

how do you know if your relay is blown? does it has a indicator like the fuse does? and where do you go get a new relay without ordering online.

I'm asking because I have this same problem last time and even my mechanic give up on my electrical problem.

Well if the fuse is good and you cant think of anything else try the relay. Its like 11 bucks at pepboys.

[916S14]

can anyone shed some light as to whats going on in my car?

[KiLLeR2001]

Sounds like a loose wire somewhere if it works sometimes, and other times it doesnt.

Looks like your only option would be tracing the entire fuel pump lines to see anything suspicious.

[Nackers]

I have a couple questions. It is a bit complicated so bare with me.

1994 240 with Redtop SR20DET
Stock, stock, stock setup.
FMIC
Stock Maf
Stock Turbo
Etc.

A bit of background. About 4 weeks ago I sucessfully started the car with a Mine's tuned ECU with zero problems besides for the idle and that from running the ECU on a stock setup. Everything worked fine.

I bought a E5 ECU that was previously blown somehow. He jumped the burnt part with wire and a fuse and said it worked. I know the guy and he's a good guy so I believe him when he says this.

I threw the ECU in the passanger seat and it bounced off and landed on the floor. I put it in my car and noticed the fuel pump wouldn't prime. I checked the ecu first to make sure I plugged it in all the way and heard a spark followed by the popping of the fuse.

I opened the ECU cover to find the soldered joint came unconnected. Presumably from me dropping it. I had my friend re-solder the joint and check to make sure it wasn't shorting to any other connection.

Put the ECU back in the car and still the fuel pump won't prime. Checked the fuse with the DVOM along with physically looking at it. I took the pump out to make sure the wiring was still connected and checked everything with my DVOM. I found that the 6pin connector going to the pump had no power going to the pump, but power for the fuel level.

I got on here and found this post...

go by your battery. unplug the little red plug tucked in the fender well. grab the male end of the plug and put your test light (which needs to be connected to your postive battery terminal) and probe the black/pink stripe wire. turn the key on and see if your test light will light up for the first 5 seconds then go out. if yes, now try cranking your motor. your test light should stay lit while you're cranking the motor. if it does both of these things, then your ecu's fine. and somewhere from your fuel pump relay to the fuel pump there's a break in the wire. you can either trace down the open , or run your own power wire from the relay to your pump. or i'll tell you how to wire in your own relay...just depends on how tired of this problem you are :D

test those 2 things and report back lol.

Dave =]

First with that male plug. It should be going to ground and not power right? I put it to ground and the relay clicked and the pump came on.

Second is the result.

I put the test light into the male end of the plug and the other end to ground. Turned the key and the pump turned on but would not shut off after the few seconds when it should. Unfortunatly, my battery doesn't have enough juice to crank but for a few seconds before putting it back on the charger but I did attempt to crank it and the pump did stay on. Turn the key off and the pump stayed on along with the "brake" light in the gauge cluster.

I'm wondering if this means that either...

1. The black/pink wire is broken somewhere from the plug to the ECU

2. The ECU is bad.

Like I've said, I've had other problems with this ECU so I'm leaning twords that, but I'm not sure if either of these are even the right conclusion and that it is something else instead.

One other question is the S14 FSM for the ECU pinout the same as a E5 or #62 so I can check resistance between that reddish plug with the black/pink wire to the ECU to confirm if the wire is bad or not?


Thanks for your help.

[Z U L8R]

i was saying put the test light on the POSITIVE battery terminal, that way whatever you touch with the test light, if it's a ground your light will light up. so when you unplug the reddish/brown plug and probe the black/pink wire that goes back through your firewall to the ecu (the male side). you're probing for the ground signal that the ecu is sending it. the ecu should send that wire a 5 second ground to prime the fuel pump, then a constant ground during cranking.

if you had your test light connected to a ground and you were grounding the relay (female) side of the reddish/brown plug then your test light was giving the relay the ground it needs to run the fuel pump and that's why it continued to run and run and run.

to the original poster. good job on fixing it. it could have just had a bad connection. these cars are 20 years old now, corrosion is starting to play a part in some instances. now aren't you glad you didn't buy an ecu :P

Dave =]