Help with fuel pump and relay Power but no Pumping

[2fast4y0u]

ok so car ran just fine 2 days ago. got new chips from enthalpy today and went to start it and nothing.
traced it back to the fuel pump not working. call enthalpy, they said the tune has nothing to do with the fuel pump. put old chips back in, nothing!

so, i checked the fuse, its good
checked the power going to the fuse, its there
checked the ecu fuel pump relay pin 104, power there too
checked the 2 wire harness on top of the fuel pump "hatch" NOTHING
checked the 4 wire plug and with the multi meter on the red and black wire in that plug i have power at the red wire...


pulled the pumped and checked it, its good, cycled just fine


so what am i missing here?
i have a back up pump and it works but whtas the point of putting it in if the old pump works out of the car.

where is the fuel pump relay located? i read in the FSM thats its by the fuse panel under the drive side kick panel...does anyone have a pic of it? there are a few down there and im not sure which is which.

car is a 98 with redtop in it. have had the swap done for 5 years now and never had this problem

[r20crazy]

check all your ground wires. i know on my ka s13, if one of the upper harness ground wires that connects to the back of the valve cover/head isnt connected the fuel pump wouldn't work and I was getting power everywhere except to the pump. took me about 2 hours to figure this out as it was just a small black wire late at nite. maybe something similar in your application

[2fast4y0u]

update:

theres power at the #104 pin on the ecu (fuel pump relay trigger)
if i jump the power from there to the plug on the pump the relay Buzzes" really bad but the pump works
if i remove all jump wires and turn the key on, Nothing.
i removed the blue cap on the relay and noticed when its buzzing there are sparks between the contacts when i its "buzzing"
if i take a screw driver and manually press the contacts together, no sparks and the fuel pump works properly.

i replaced the relay and it does the exact same thing as stated above.
i checked the grounds on the relay and blew 2 fuses

[Josh_300ZXT/240SX]

I'm having the same prob. with out blowing the fuses but the pumps not working? Any update on this! Did you get it fixed???

[Om1kron]

sounds like a thread blew on the ecu.

open it up and see if it's burnt.

3993561

[codyace]

Check to see if the relay is getting ground signal from the ECU to trigger the relay switch. Also ensure the relay itself is getting power.

[JVD]

I don't see how you're getting power on the ECU trigger wire...

It it grounds the relay to trigger.

[codyace]

I don't see how you're getting power on the ECU trigger wire...

It it grounds the relay to trigger.

I mentioned above it's ground.

But the relay is still going to need switched power, and constant power to operate too.

THis way he can help diagnose if the relay has an issue on ground or power side.

[2fast4y0u]

forgot to update 3 days ago...
heres the results: (i wish jspeath issue was this easy to fix)

after tracing down the symptoms my ground wire was getting 12v to it. i clipped the black/pink wire from the ecu and grounded it right to the chassis. my fuel pump worked again, BUT it was on constantly when the key on.
i started looking in to the problem again 3 days ago because im in the process of installing an AEM ems. turns out, one of the main 12v source wires to the ecu got a little toasty...
melted the insulation on the wire and was hot enough to melt the insulation on the black and pink fuel pump relay wire...therefor making my fuel pump fail.

problem solved! still havent figured out why the wire got so hot (obviously touched a ground) but not sure how. Also, i reconnected the black/pink wire to the ecu and fuel pump now primes like normal when key is turned on. THANK GOD!!!

thanks for the help fellas. Much appreciated.

[JDMRIDDAZ]

the best thing is to rewire the fuel pump separate from car....
(not outside of car)
triggering a relay powered by battery and turned on with ignition...
Ive got an 89 coupe w sr20det w/fpr with no issues at all
the older cars circuits tend to have a lose of voltage under driving conditions

[codyace]

problem solved! still havent figured out why the wire got so hot (obviously touched a ground) but not sure how. Also, i reconnected the black/pink wire to the ecu and fuel pump now primes like normal when key is turned on. THANK GOD!!!

Hehe, funny youmention this, as I was telling Justin this exact same story with my car. Somehow it back fed one day and the pump began to stop priming through the ground signal from ECU. Did the exact same thing as you did to solve it, hence why I said check that ground side to the relay. Rocking that it worked.


the best thing is to rewire the fuel pump separate from car....
(not outside of car)
triggering a relay powered by battery and turned on with ignition...
Ive got an 89 coupe w sr20det w/fpr with no issues at all
the older cars circuits tend to have a lose of voltage under driving conditions

Agreed, and I have since done the same as well. This helps keep a solid battery voltage to the pump as well at all times, with the relay

(I simply ran wire from battery to a relay in the back, and then the relay to the power side of the pump. I used the factory 'power' from the fuel pump relay as the trigger, so it works just like stock)

[g6civcx]

(I simply ran wire from battery to a relay in the back, and then the relay to the power side of the pump. I used the factory 'power' from the fuel pump relay as the trigger, so it works just like stock)

I don't know what all this means.

Battery - 15A fuse - both pins 85 and 30 of the relay

Pin 86 to ECU fuel pump relay ground

Pin 87 to fuel pump

[JDMRIDDAZ]

s13 r older cars...
and when u put accessorys on gauges 255walboro..hids..update all bulbs to leds...u need to create a electrical subsystem to support these things with voltage...
needles to say s13 and s14 alts only put out like 90amps....
everything need proper voltage ka's sr's rb's it makes the engines perform way better and even spit fire.....

[codyace]

I don't know what all this means.

Battery - 15A fuse - both pins 85 and 30 of the relay

Pin 86 to ECU fuel pump relay ground

Pin 87 to fuel pump

I'm talking about rewiring the back, and not using that 20 gauge junk that they come with factory, not diagnosing the actual fuel pump relay.

[g6civcx]

I'm talking about rewiring the back, and not using that 20 gauge junk that they come with factory, not diagnosing the actual fuel pump relay.

I understand now. You're using double relay fuel pump trigger.

[2fast4y0u]

hmmm. i like this techy wiring info. if some one could be so kind to explain it in a way that i(dumb person) could understand, that would be great.
i would love to track down my electrical draw and i think it all stems back to my walboro. ever since i installed it, my volts before key on, ignition on will go from 12.5 to 10.5 after start up.

[willow 2point0]

I have a similar problem, in my sr s13. But I'm not getting power at all at the harness clip that connects to the fuel pump clip. I ran a toggle swich connected to a 15amp in-line fuse connecting the battery to the fuel pump, then grounded the fuel pump to the battery itself. I left the clips connected together, cause I'm really not sure what those other two wires do. I just figured they were for the gas gauge, or something.
But I've heard that running a manuel toggle to the fuel pump will burn it out fast, yet it's fused (afformentioned 15amp in-line). After 10mins or so of driveing time the pump gets a bit loud.
Help? Please?

[willow 2point0]

I have a similar problem, in my sr s13. But I'm not getting power at all at the harness clip that connects to the fuel pump clip. I ran a toggle swich connected to a 15amp in-line fuse connecting the battery to the fuel pump, then grounded the fuel pump to the battery itself. I left the clips connected together, cause I'm really not sure what those other two wires do. I just figured they were for the gas gauge, or something.
But I've heard that running a manuel toggle to the fuel pump will burn it out fast, yet it's fused (afformentioned 15amp in-line). After 10mins or so of driveing time the pump gets a bit loud.
Help? Please?

[iHateMySilvia]

im having same problem as OP , can anyone help me rewire the fuel pump separate from car... what do i need etc plz pm me

[iHateMySilvia]

also im getttin no signal to ign coil and dizzy, car turns over but gets no spark! could it be my ecu? grounds ? harness? someone help! :,(

[JDMRIDDAZ]

grounds on back of engine dr side wil do that...
no dizzy and coil....

Pin 87 gets 12v
Pin 86 gets ground.
Pin 85 gets switched ignition
pin 30 goes to fuelpump wht/purple at f/pump
http://www.google.com/imgres?imgurl=http://www.steelnthings.com/pins1.gif&imgrefurl=http://www.steelnthings.com/auxiliarylights.html&usg=__kqgNDzArRYvHrKtcr-TYIxX6384=&h=504&w=504&sz=6&hl=en&start=0&tbnid=u30gcYrgyhXa-M:&tbnh=137&tbnw=137&prev=/images%3Fq%3Drelay%2Bpins%26um%3D1%26hl%3Den%26cli ent%3Dfirefox-a%26sa%3DN%26rls%3Dorg.mozilla:en-US:official%26biw%3D1280%26bih%3D560%26tbs%3Disch: 1&um=1&itbs=1&iact=hc&vpx=349&vpy=206&dur=131&hovh=225&hovw=225&tx=109&ty=141&ei=PJxeTPWMGoL98Aanw8yyDQ&oei=PJxeTPWMGoL98Aanw8yyDQ&esq=1&page=1&ndsp=18&ved=1t:429,r:7,s:0

[2fast4y0u]

my power wire simply got a lot of feed back and was supplying 12v to pin 84(fuel pump ground) and that was not letting it prime or work.
i seperated thos wires and it works like new again