No power to fuel pump.
 

I've checked the resistor/relay and it's fine. and there is a relay under the dash that is also working. all the fuses at the left front shock tower are all good. i also checked the fuse box in the footwell, but none say fuel pump. is there another link somewhere that i'm overlooking. please help, this is my only mode of transportation. and all my friends went home for christmas.

More details on the car (mods, history) and the situation. Does the car just turn over and not start? how do you know its the fuel pump?

there is a fuse for the fuel pump. it'll just be labled something else like efi or something. can't remember off hand.

how are you checking it? do you know it's not supposed to have power unless the car is running right? with the key to on and car off there is no power.

if you want to check for power. there is a jumper connecter on the pass side shock tower. jump that. turn key to on. and you should have power.

ya, i jumped that yellow plug. and no power. i've had the car for over a year and last week it started intermittently messing up... (felt like fuel cut but had backfire) and another time just felt like it ran out of gas but kicked back in again. stalled in a parking lot once. and lastly, stalled while driving. thankfully i was close enough to coast home. hasn't run since then(Dec. 16)

used a voltmeter and measure no voltage coming from the plug on the left rear shock tower with key on and yellow plug jumped.


oh, mods in sig.

since i'm having this problem, i figured now would be a good time to do the fuel pump rewire precedure. it won't fix the problem tho since this setup still requires the use of the old wiring to switch the relay. and if i'm not getting any voltage to the relay, i will still have an inoperative pump.

Use a wiring diagram to trace the power from the fuse, via both relays, to the pump. Check every point along the circuit for power. That way you can isolate where the problem is.

1. Pull the ENGINE FUSE out. It's in the crew compartment. 15 amp fuse. Third row up counting from the bottom of the fuse box. Second one from the lefc if you were looking straight into the fuse box.

2. If that's good, pull the Circuit Opening Relay located under the dash and above the steering wheel. It yellow in color *I think*. With the key to ON, see if the Black/White wire has 12volts on it. The larger gauge Black/White. NOT the smaller black/white. If it does not have 12v then consider that it gets fed from the afore mentioned 15 amp ENGINE fuse. That 7.5 fuse gets fed from the IGNITION SWITCH when it is to ON or above. The ignition switch gets fed from the 80a fuse in the engine compartment. The one in the middle that is bolted in .

4. Wiggle the key in the ON position if there is no 12v at the Circuit Opening Relay. If 12v comes and goes, then the ignition sw is suspect.

5.IF that does not help......there are three plugs that go to the ignition sw. They are about a foot or so down the steering wheel. One has two wires in its two sockets. One is Black and the other Black/White. The Black should have 12v on it whether the key is on or off. The ignition sw is not a factor when looking for this 12v. If there is no 12 on the Black wire coming from the direction of the engine compartment, look for a bad connection in that black wire at its other end which is a single socket plug about a foot below the engine fuse box.

I've attached the wiring schematic for the Turbo fuel system many times on this forum. It's out there somewhere.

Similar to this one:
https://www.rx7club.com/forum/attach...&postid=914413https://www.rx7club.com/forum/attach...&postid=914413 \

What your doing is, is childs play. Try fixing a busted cruise control switch (the handle part with the push to set switch in the end). Try finding the smaller than a beebee ball, its spring, the *push spring*, and the metal bridge that makes the contacts. All somewhere on the floor of the car. Then figure how it went together and a way of epoxying the thing back together without permanetly glueing moving part together.. I'll swap problems with you any day.

lol well, i checked voltage at the fuse and getting about .5 volts less there than at the battery. checked the solid black wire going to the ignition and same thing. checked the B/W wire from ignition and no voltage until key turned to on.... when i check the big B/W wire at the circuit opening relay, i get nothing. but i have continuity between the ignition switch and circuit opening relay. i don't understand.

obviously i'm no electrician.

also, unplugged both terminals of the battery. i'm getting continuity between the solid black wire going to the ignition and ground. does this mean that it is possible shorting out somewhere between the battery and ingition switch?

Magnet? :)

Forget about the reading b/t the battery terminals with them disconnected. Your just reading back thru relay coils/grounds etc . Forget that.

2. You can read b/t the ignition sw and the circuit opening relay doing a continuity check? But if the key is turned to ON you don't have 12v at the large wire at the relay?????? That's possible. Sometimes you can read continuity, but if a LOAD is put on the circuit you might read zip because there is a loose/broken/flakey/held on with one stand ...connection in that circuit b/t the ignition and the relay.

What happens if you go to that ignition plug with the Black wire and the Black/White wire.....and jumper the two together with a piece of wire??????

Actually though...you said you have 12v at the fuse. I'm guessing the bad connection is there on one side of the fuse or the fuse isn't making good contact in its holder.

Forget about the .5volt loss. Not relavent. Forget about the battery terminals reading to each other. Not relavent. Concentrate on the BW wire at the ignition and how it runs from there to the 15a fuse....then goes to the relay base. Something is whacked there.

A side thought is to take the Main Relays two socket plug off and see if you have 12v on the Black/White wire there when the key is to ON and the connectors are attached at the ignition. The Main Relay has little to do with the pump problem....but you might notice that there is a splice off the circuit opening relay that goes over to the Main Relay. So if you see 12v there and not at the black/white wire at the relay base...concentrate then on the base of the relay. Something like that.

I'm going to pull the fuse box out tomorrow and check behind it for loose wires. Cause I get 12V to the fuse but not to the relay. So, I'm figuring there is something wrong between the fuse and the relay.

I think we're miscomunicating just a tash. From re-reading your post I've come to the conclusion that maybe,just maybe your looking right at the ignition switch and making readings. Don't do that.

Below the ignition sw there are three plugs. One plug has a Black wire and a Black/white wire in it. It mates to a plug with a White/Red wire and a Black/Yellow wire. You want to de-mate those connectors where you can put your meter in the socket where the Black/White wire is and then check continuity b/t there and the Black/white wire in the relay base.

Since I had the wifes steering wheel off anyway, I pulled the relay base off and then pulled the plug from the ignition switch with the Black/White and Black wire off , and checked continuity b/t the black/white wire at the relay to the black/whit wire at the two socket connector. You should read .000 ohms. You might read something like 1.87 K ohms if the fuse is out. That is to be ignored. It's nothing.

One thing I noticed on this car. The two socket plug located about a foot below the ignition sw .....when I pulled it apart from its mate....it was not locked together with its mate. It almost fell off its mating connector (the one with the black/yellow and white/red). So make sure that connector is mated up good in the future.

So if the above is true.......don't pull that fuse box just yet.

well, i was measuring at that connector before, this time, i unplugged it like you said. also unplugged the relay connector. i measured about 18ohms in the wire with fuse in. does this mean anything to you??

18 ohms seems a touch high, but tell you what, I still have the car at home apart and I'll ohm mine out tomorrow morning around 8-9am.

Have you tried this? Jumper the pure black wire to the black/white wire. That should put 12v on the black/white wire and you should be reading 12v now at the black/white wire in the relay base. Does that happen. With the fuse in place? If that does happen, I'd be looking at the ignition switch.

Just to be sure we're at the same plug. One plug has a black wire and a black/white wire in it. It mates to a plug that has a black/yellow wire and a white/red wire. You have the same two plugs that mate together?? Probably, just making sure.

ya, that's the same plug. only mine was a bitch to detach. took me 10 minutes or so. although, mine does have a latch thingy on it. it was in there quite well.

and i don't think it's necessary to jumper the connector cause i measured 12V constant on one of the black wires and 12v on the other one only when the ignition was switched on. at least i assume that's how it worked.

when i have some daylight tomorrow, i'm gonna run a ohm test from the fuse to the ignition, and from the fuse to the relay plug. just to see where the resistance is coming from. i don't think 18ohms is anything, but i'll check anyways.

I think it should be less than what you read. I would have expected one ohm or less. That's if you put one lead of the meter on the Black/White wire of that two wire connector and the other lead on the black/white wire in the relay base.

Maybe rig the meter up like that and then while it reads 18ohms, wiggle the fuse and the wires around it and see if the meters reading changes.

I'll see what mine reads in the morning.

ok i'll do that. i'll let you know as soon as possible.

On my car: With one lead in the black/white wire in the relay base and the other lead in the black/white wire in the two socket connector for the ignition I have .5 ohm with the fuse in place. If I remove the fuse I get 88 ohms.

IF I pull the fuse out and I leave one lead in the two socket connector and put the other lead at where the bottom leg of the fuse made contact in the fuse box, I get the .5 ohms again.

You might take both leads of your meter and touch them together and see what the resistance is just in the meter leads, then subtract that figure from the reading you got earlier......what? 18ohms. I forgot.

On my car: With one lead in the black/white wire in the relay base and the other lead in the black

well, with the fuse in, i get 18 ohms and when i take the fuse out, i get 35 ohms.

if i check the individual legs i get 0 ohms between the ignition wire and the bottom leg of the fuse and 74 ohms to the top leg.
and 39 ohms between the relay on the upper leg of the fuse and 36 ohms to the bottom leg of fuse.

oh, and i shook the wires and fuse box with the ohm meter attached, but no changes.

How about *I dunno*. I don't see why you shouldn't get .5ohm or less b/t the relay's black/white wire and the fuse. Unless there is a bad connection at the fuse box or at the bottom of the relay base where the black/white wire is.