Electrical bug???

[AirtekHVAC]

Ok, got oil filter on, plug in, oil filled. Now to get the pumps running....got 12v to ground on 30 at fuel pump relay (may be 87) and voltage across 30-87 which tells me i have potential..which tells me open circuit, as it should be. I jumper 30 to 87, and nothing happens. I check my pumps, and got no power....so I start tracing.... Now I may be answering my own question here, but.... I have previously cleaned ALL my ground points, EXCEPT.... the one behind the passenger side tail light.... I pulled the panel back a little, and looked with a light, can barely see it, but it looks very "tarnished". Could this be my problem? If the answer is yes, should I still not have had 12v on the positive wire at my pumps when measured to ground?

Input, thoughts, suggestions? I already will tackle the obvious and clean that ground tomorrow.

Thanks!

[Guest765]

I don't know enough about the 928, yet, to be too helpful. But really cleaning that ground is nothing but helpful.You can get 12v which means NOTHING if you dont also have enough CURRENT to turn the pump over. An easy way to understand is you can have 12v with a couple AAA batteries wired together. Your car battery also has 12v. The AAAs will not JumpStart your car though because the starter needs high current 12v. Volts mean nothing.

[Kiln_Red]

So, with a jumper wire in place, you are applying a 12V test light to the fuel pump connections? If you have power to (30) in the relay socket, then you should have power at the pump. Make sure you check both fuel pump connections and that your test light on a good ground. The fuel pump is likely frozen from fuel varnish.

[AirtekHVAC]

Fuel pumps are brand new....using a fluke meter at the pumps...no voltage whatsoever at either pump from positive to a good grond. There is a barrel style connector in the battery compartment. Don't know if that is where it is fed from, but it was in good condition. I went ahead and took it apart and polished the connections anyway.

[Kiln_Red]

I assume you've checked the wire leads at the (+) and (-) connections for the pumps for corrosion or a loose fit at the exposed wire ends? You should just have one electric, in-line pump. What kind of pump is it?

[AirtekHVAC]

I have dual pumps, one under the tank, one in the fender well, connections all clean. entire fuel system is new / refurb. Pumps are brand new cant remember brand...bought them in May.

[Kiln_Red]

Scroll here to find a copy of your MY wiring diagram. This should provide additional information on ground points and give you a quick reference for your CE panel. I'm not sure how the wiring is fashioned on your car as I have no experience with CIS cars with the additional pump at the right rear wheel opening, so I'll scratch my head on it as well.

[AirtekHVAC]

Thanks...I have that diagram somewhere. The CE has been replaced/refurbed (by me), all relays bench tested and working....all grounds cleaned, (except for the fore mentioned), its either a bad connection, or a broken wire somewhere....

[Fixer]

Going to have to trace back from the pumps..

Maybe just to get it running, bring fused 12V to a switch in the glove box or where ever and then back to the pumps to get the car going, tuck it under carpet edge..
Get that motor warmed up for us we can't wait.

Find the problem later and remove the added wire.

[AirtekHVAC]

Egg zactly what I was thinking...got plenty of wire, fuses, and fuse holders...lol...might have to make a custom harness....

[DPW928]

Did you check the voltage at the small connectors at the pump? The 928 is set up for Bosch pumps which use a smaller connector for the positive and a larger connector for the ground.

On your bypass wire, make sure it's a heavy gauge as two pumps will draw a lot of amps. Have you checked the 30 relay connection at the fuse box to make sure it has 12 volts? If you have 12 volts at the relay 30 connection, the problem is in your wiring between the relay and the pump. If you don't have 12 volts at the 30 connection, check the large red wires at the bottom of the fuse panel to make sure you are getting 12 volts to the panel.

Dennis

[AirtekHVAC]

Yes, checked the smaller connectors / positive at pump, got heavy wire, 12 volts at 30, panel hot, 12v at all switched/ non-switched fuses depending on key position. Anyone know where the harness runs from panel to rear? Looks like perhaps down passenger side, behind rear panel, and I am guessing under carpet /along under door kick panel?

[DPW928]

Not sure how the wiring loom is laid out. Did you trace the ground wire off the pump to the body to check its connection? IIRC it connects at an area separate from the rear lights. Also, did you check the battery ground cable to make sure there was no corrosion?

[AirtekHVAC]

Battery ground cable is good...tried to trace pump wires, they are in a jacket /loom, and appear to come up in the trunk.

[Mrmerlin]

good that your moving along a few questions
Did you drop the CE panel to verify that power is indeed coming out of both sides of the fuel pump fuse this could be your problem
did you clean the ground under the rear quarter this could be your problem for no ground

[DPW928]

IIRC there is a common ground point behind the tool panel at the rear of the hatch. May want to check it.

[AirtekHVAC]

Ok. Found the first problem....to start, I did not clean the ground behind the tail light...can't quite get to it. I can see it, and it looks ok... It is on the list.

What bothered me was that I had no 12v on the positive terminal, that just made no sense...so I start tracing wires from the panel, and
something caught my eye....

When I replaced the CE, I labeled every plug connector along the bottom alphabetically...leaving out "I"

Well, unless T comes before S these days, I had a plug reversed....switched the plugs, and viola! Power to the pumps...geeze....which leads to problem 2.

The pump leaving the tank will not run....just hums....I tried to reverse the leads and bump it, but no such luck. I bought these in may on ebay, so I can't send it back.... No big deal, BUT I don't think the one pump is able to suck through the other..... Thoughts? I really wanted to crank her this weekend...looks like I will have to wait for a replacement pump

[DPW928]

Two pumps were only installed by the factory for early 928's destined for hot environments so yours would probably function OK with just the external pump. I would remove the internal pump assembly and remove the pump portion and refit the strainer and reinstall.

BTW, you do have gas in it? 8^)

[AirtekHVAC]

The pump is external, I just don't have fittings to bypass it. It originally had it, so I wanted to keep it that way, but I think I am going to make myself a copper bypass line right now so I can see if she'll run.....stay tuned

[AirtekHVAC]

Ok...SOLVED....as far as the electrical bug goes....so this thread is by no means closed for discussion, but the original problem resolved. I made a fuel pump bypass line out of copper...will post some pics later tonight, if our company leaves at a decent hour....I got more to tell in a new thread!