HELP!!! fuel pump voltage?

nwnsc

Registered User
im haveing a fuel pump problem. i cut a hole to make a accese panel. when i got it open the plug on the tank was burnt to the point when i pulled it off it crumbled in to hunderds of peces:eek: now i have a new plug in i only get 6.5 volts to the pump with the key on:confused: i would think it should be closer to 12 volts? so please help. nathan
 
What color-coded wires are you working with? Pink wire/black stripe supplies 12V to the fuel pump.
 
the pink is only give me 6.5 volts. the black ground is testing good as far as haveing aa good conection. i get the same 6.5 if i ground to the body. the bat has 11.5 and has good conectons and cables;) why am i geting only 6.5 volts with the key on?:confused: think i should replace the pump realy?
 
Yep, I'd move right to the relay & safety shut off on the left side of the trunk. No telling what else has taken a hit :(

Do you have any kind of anti-theft device that shuts off power to the fuel pump/relay...if so, don't forget to verify health there, etc.
 
i put a new realy and checked the safty switch. still only got 6.5 volts:rolleyes: i still have to put in the new pump when it comes but my old one works it is just a wire thing:confused::rolleyes::eek::(
 
nwnsc> i put a new relay and checked the safty switch. still only got 6.5 volts

Step-by-step. Keep moving/checking thru the wiring - got a diagram? What year?

Any blown fuses...at all?

You may want to pull the PCM loose, flip it over and see what, if anything, got fried under there.
 
90 anny is the car. the pcm would that be the irmc or the eec? and as far as a diagram all i have is the factory service book so wiring diagrams are limited in there. i need the wireing book:rolleyes: should of bought it when i saw it on ebay for $15 shipped:eek::rolleyes:
 
Sorry, I meant the power control box that holds fuses & relays, right next to the battery. I think there are one or two bolts that hold it in...it then slides off a bracket so you can get to the underside. Sometimes the wiring that comes in from the bottom gets melted and it's not obvious from the top even if you pull fuses/relays.

I have a 35th also & wiring diags so if you need a reference, let me know and I'll try to help from those if I can.
 
so it runs from the fuse box to the realy to safety switch to the fuel pump right? i will go out and check the fuse box for melted wires and see what the voltage is at the box and the realy are.
 
nwnsc> so it runs from the fuse box to the relay to safety switch to the fuel pump right?

The safety switch is on the trigger side of the fp relay, not the power side. Power isn't directly shared between the two.

Power goes: fuse box (30A HD)--->relay--->pump
(& pin 19 @ EEC).

There is a diode (EOVB-14A604-AA) at the pump - testing gets tricky and best done out-of-circuit, but if you go that far, you might as well just replace it.
 
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this is the 2nd SC that i had fry the tank plug but the last on i switched ot thr plug and it worked fine. i just cant seem to find the short in this one. i got some time right now im going to go check the volts at the realy and the box, and see where the power drops:rolleyes:
 
Yeah, I think I recall the other one...man, you've got some tough luck w/these. Have you swapped any electrical related components between the two cars at all?

I think you're doing the right thing by checking voltages, since it seems clear you have more than just a toasted connector like last time.

I suspect at least one other melted connection since you're seeing a voltage drop. See what you get across the connections inside the fuse box first, perhaps...if that's ok, you might not need to go to the trouble of pulling the box - I've seen photos of some pretty grisly conditions hiding on the bottom-side, however, so it doesn't hurt to eyes on when you have an electrical issue like yours.
 
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and thank god for a good Snap-on volt meter;):D and i have found this kind of stuf before with conctions that elect. grease drys out and just frys plugs
 
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I checked the wiring at the relay and if I jumper it I get 12v at the pump, but if I use the relay I only get 6.5v. I've tried 3 different relays....an old one, a new one, and one out of another car, and I still only get 6.5v. I checked the trigger side of the relay...I'm getting 12v in and 12v out with the key on. Once I found I had a bad ignition switch. I got that fixed, But I'm still only getting 6.5v. Where do you think my short is? Do you have a diagram for the fuel pump wiring? Thankyou, Nathan
 
I checked the wiring at the relay and if I jumper it I get 12v at the pump, but if I use the relay I only get 6.5v. I've tried 3 different relays....an old one, a new one, and one out of another car, and I still only get 6.5v. I checked the trigger side of the relay...I'm getting 12v in and 12v out with the key on. Once I found I had a bad ignition switch. I got that fixed, But I'm still only getting 6.5v. Where do you think my short is? Do you have a diagram for the fuel pump wiring? Thankyou, Nathan

How did you jumper/bypass the relay? At the connector?

Probe the relay ground @ the connector and see what the resistance is.

I'll work on scanning a diag. for you.
 
How did you jumper/bypass the relay? At the connector?

Probe the relay ground @ the connector and see what the resistance is.

I'll work on scanning a diag. for you.

I pluged a wire in at the connector...

I will go check the resistance here in a sec...

Where is it grounded at? So I can check the terminals...

Thanks Nathan
 
Check this...the image is scaled down when uploaded - the original is large and crisp. I can upload it elsewhere or email it to you if needed.

Ground is at the pump.
 

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Check this...the image is scaled down when uploaded - the original is large and crisp. I can upload it elsewhere or email it to you if needed.

Ground is at the pump.

thanks for that pic!!!! i checked all the wires. the only thing i think it could be is the eec fryed that curcit inside because all the wires and conectons look good. even checked pin 19 on the eec:rolleyes: so i don't know what to do try to put a new eec in it:rolleyes: or just wire it on a switch;)
 
> try to put a new eec in it

That could well be the culprit at this point. Might be worth just disconnecting the harness at the EEC long enough to check again and see what happens. Also, do you know how to jumper at the self-test connector to force the pump to run? Maybe one of these can help isolate the main problem.

Did you happen to pull (at least KOEO) codes? [Fuel pump circuit failure...556?]
 
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