Fuel pump issue

[turbo39151]

Here'e the deal:

Car was running fine. Went to start and got no fuel pump. Checked the fuses.- All good.

Checked my power to the rear and I get 8.70v. I checked my other TR's and they all started with 8.7v. I tap the old pump and the new replacement (since I thought the fuel pump was bad.) with a 9v battery and no response. I tap them with an 18v battery and they jump.

If I have power and ground and two known working units, what am I missing??? I am stumped. Gimme some ideas guys...

 

[turbo39151]

nobody?

 

[turbo39151]

ttt

I need to fix this weekend

 

[turbo39151]

I even swapped a known working fuel pump relay. Still no fix.

I have a hot wire kit on this but shouldn't be an issue if car isn't running.

 

[SIXBANGR]

ecm

mine did this a few years ago, turned out to be some circuit in the ecm. Swap it with your other car to check. You can run a wire with a toggle switch from the fuel pump prime wire under the hood and when it starts just turn it off.

 

[GN ERGY]

The hot wire to pump comes from the post on the alternator and should have the same volts there as the battery even if the car is not running. Check your volts there and the battery. See if there is a difference. Lat us know what you get.
Tarey D.

 

[turbo39151]

The battery is 12.4v. The alt will not put out any current unless it's running.

When I turn the key to the "on" position but not to "start" I get the 8.7v to the real fuel pump connector plug.

Why is it that I have the proper power and ground yet the pump won't kick...

Even if the ECM was not working at all, I assume that having power and ground would allow the pump to start. (Of course, then I assume that the ECM should regulate how long the pump runs for- 2 seconds at the turn of the key...etc...)

AM I completely wrong here?

 

[mikestertwo]

Are you measuring the voltage with the pump connected or disconnected? With the pump disconnected it should read the same as what's on the back of the alternator 12.4v When you connect it to the pump, it should drop some, depending on how much current the pump is drawing. I assume you are measuring the voltage at the pump connector at the back of the car.

 

[turbo39151]

First, I measured the voltage at the connector at the back with the pump connected and then disconnected. (made no difference 8.6-8.7v)

I assumed that the pump was bad since I had power and ground all the way back.

I dropped the tank and pulled the pump and "tested" the pump by tapping with with a 9v battery. (I got no response)- I tested the new pump like that and still got no response. I tapped them both with an 18v battery and they both responded.

I figured I wasn't getting enough juice to the rear. So I tested my other TR's with pump connected ot disconnected I got an average voltage of 8.6-8.7v. This voltage was suffiecent to start the cars. Why is in not sufficient to start this one.

I am curious to know if in fact there is actually 12v required or if this is speculation. And if 12v is required, why do my other cars start with 8.6v?

Can you see why I'm stumped...

 

[turbo39151]

I think I've found the problem!

It looks like the wiring harnes on the fuel pump hanger assembly is corroded and not passing the current.

I'm trying to find a new hanger assembly right now. Just got off the phone with Autozone and they say they don't have it.

Can anyone help me with a location or part number?

TIA

 

[Headcutta]

Red Armstrong has them and I think Gbody parts has them

 

[turbo39151]

Ok, not the problem.

Here's what I have so far. Pump is working. I have power 8.6v (I thought I'd need 12v but my other TR starts fine with 8.6v) and a good ground to the pump. ( I isolated the ground to be sure)

The fuel pump relay has been checked and even swapped with a known working unit. I tested the ECU to make sure that wasn't a problem.

After reviewing the factory manual I cannot seem to find any other reason for the non-priming fuel pump.

I even ran a jumper from the Battery to the fuel pump and It runs fine!

Can anyone give me some additioanl ideas? I'm stumped.