Changed fuel pump now car won't start?

[jrichker]

Well I disconnected the pigtail by one of the straps that hold on the fuel tank. There were four prongs. One registered at 8 votls the other at 7, does that sound right? Wouldn't it need 12v?

Go back and read my first post. Everything you need to troubleshoot the problem is in there.

If you can read elecrical diagrams, you would see that the pink/black wire is the power for the fuel pump.
Anytime the ignition switch is in the Run postion and the test point is jumpered to ground, there should
be at least 12 volts or whatever battery voltage is, present on the black/pink wire.

 

[TheUser]

Have you measured voltage at the battery? If the battery voltage is only 7 or 8v, then you'd only get that much at that pigtail connection like Jrichker mentioned.

The whole thing with the charger makes me wonder if the alternator is working properly? Have you changed the alternator wiring?

However, I don't think a non-functioning alternator would cause this problem so quickly. I once drove home (about 10 miles...20 min counting stoplights) at night w/ my headlights on for about 4 of the miles. I had to cut them off to conserve the power and I made it about 1/2 mile from my house before the car wouldn't go anymore.

I say go w/ Jrichker's advice and measure the voltages of both sides of the wire and see what you get.

 

[69Rcode_Mach1]

Okay guys I undid the pigtail under by the gas tank, I hit it with 12 volts at the black/pink wire and then touched one of the grounds out of the four prongs, it caused the pump to run fine. So
I also checked the wires at the relays and they were getting the 12 volts necessary. I went to the ECC connector and grounded it, the relays clicked, and the pump ran, now it did this once or twice, then when I tried to jump it again, only the relays clicked again no pump. So we know the pump works. This sounds like there is a bad ground somewhere but I don't know where to start. I tried starting it, and it started and died after a few seconds, it did this again, then started and ran fine. I tried shutting it off again, and restarting, back to the hit and miss, sometimes it primed and started and died, sometimes it won't even prime. The battery is getting 12 volts, and the alternator is a new 85 amp alternator. What do I do? I am in bad shape and need to get this freaking thing running today.

 

[69Rcode_Mach1]

Also I did Jrichkers test he stated in the last post. The pink/black wire got 12volts with the ECC connector grounded, and using a chassis ground. Now I got 8 volts from the yellow wire, and .005 volts from the two black grounds. Now I noticed something, every once in a while like I stated when I jump the ECC connector it primes, but now I also notice that when I jump it and leave the it grounded, even though I can't hear the pump, I hear what sounds like someone peeing in my gas tank, or like it is boiling. Again this happens any time the connector is grounded. Could my lines be hooked up backwards? I don't understand how the car could run sometimes if they were hooked up backwards?

 

[HISSIN50]

I went to the ECC connector and grounded it, the relays clicked, and the pump ran, now it did this once or twice, then when I tried to jump it again, only the relays clicked again no pump.

The pump should run non-stop (with the key on) when the self-test connector terminal is grounded.

If the car ran fine with your jumper power hooked-up at the tank, you might deduce your plumbing is okay and it's a control side wiring issue. I'd want to be testing things during one of the times when the FP relay clicks but doesnt work as it should.

Good luck.

 

[69Rcode_Mach1]

Okay when I hook the battery up to the charger and put it on the 225 amp setting (Start) and then I just jump the ECC connector, the pump will run for as long as I keep it connected, the car will start, idle, and drive just as it should, but it seems like it needs a little extra juice to do it. I can disconnect the charger at that point and drive the car, and it will be fine, but if I shut it off again, no luck. What is the deal? The pump and the wiring is okay, and I put in a brand new battery which didn't do anything, except on the first attempt it primed, started, and drove, after that same situation. It's like my battery is not big enough. AHHHHHHHH!!!!!!!! And yes it is the correct twelve volt battery. I have no idea at this point what is going on. I have also tried disconnecting the battery for a day, and resetting the computer to see if that helps, with no luck. Any ideas?

 

[jrichker]

Use your DVM to measure the voltage across the battery while the engine is running. You should see a minimum of 13.8 volts.

 

[69Rcode_Mach1]

I think it is the fuel pump itself. Now that it is on 225amps it will start, but not stay on. That's what I get for buying a piece of **** autozone remanufactured pump. I am trying to get the voltmeter on it but i can't keep it running long enough. I know the alternator works it is a new one, I just replaced it because my old stock one crapped out. The battery is brand spanking new also. I have warranty on it, so it looks like I am going to have to drop the tank again, where can I drain it from cause it is full now. And go get a new one. What do you guys say?

 

[69Rcode_Mach1]

Okay I managed to keep it on while my brother took a reading for me. I had to keep feathering the gas to keep it running for a 15 seconds, and it was around 1500rpms which put it at 14.0 volts on the voltmeter. I don't have one bright idea.

 

[HISSIN50]

I'd take a step back and start over with the diagnostics. Jumping around leads to bad testing theory and ideas get omitted (I speak from experience). Go back over the lists of things to check.

A couple things to remember:

The best pump in the world will not work if there's not sufficient amperage or an intermittant wiring issue.

New parts doesn't = good parts. I've received batteries that would not pass a load test brand new (I have new batteries and electrical items bench tested before I buy them).

Before assuming the pump is bad, you need to assure you *always* have 12.6+ volts reaching it (and more like 14 volts with any amount of RPM over idle). If you dont, there's no way of knowing the pump is bad, and a new pump will act the same way as the old one.

Good luck.

 

[69Rcode_Mach1]

I understand I am just getting very very stressed out over this. I need to have a car, the Mach 1 is not a daily driver. I am getting the voltage necessary, and the alternator is doing its job. It's just hit or miss, one time it works, one time it doesn't. I don't understand how all this stuff could go wrong. All that happened was that my fuel pump died. I know that it was the pump, because the pump was very loud for the last couple months, then I ran the tank dry, and the car shut down. Put gas in and no prime, no start. So I know that the old pump was bad. The only thing I would tihnk that is causing all this headache would be the pump itself.

 

[HISSIN50]

Did you happen to jiggle any of the solenoid's wires around to see if that makes any difference?

If the issue is really that intermittant, goosing the wiring till it acts up is something I might try.

We don't want you to have to hot wire the FP so you can get around, but it has been done..........

 

[69Rcode_Mach1]

Well guys I went through with it, and got another new pump. Car fired up and ran like a champ. Oh well atleast I know all my wiring is in great shape. But now that seal on the filler neck to the tank is bad, I am driving and dripping gas everywhere. Do need to drop the tank again to get that, I really hope not. Can I just undo the filler neck from the top and bottom and pull it out to change that seal, and just press it back in?

 

[HISSIN50]

Well guys I went through with it, and got another new pump. Car fired up and ran like a champ. Oh well atleast I know all my wiring is in great shape. But now that seal on the filler neck to the tank is bad, I am driving and dripping gas everywhere. Do need to drop the tank again to get that, I really hope not. Can I just undo the filler neck from the top and bottom and pull it out to change that seal, and just press it back in?

I don't know how little one can get away with doing. I can say the last one I did (on an SN95 but same difference) was still simple. The filler neck was loosened and the tank straps undone. This gave enough room to R/R the gasket pretty easy. I'm sure guys have done less to swap one but I didnt want to rip a new gasket on a Sunday afternoon (it was the owner's driver).

Good luck.