Got the fuel sending unit out no problem. Unhooked the old pump. Then looked at the 85 and a completely different wiring set up. My 84 sending unit has a light brown wire that's hooked up to a terminal at the top and just runs out into this box looking thing. The black wire beside the brown in the terminal goes into small cylinder type thing. Two black wires come out of that. Those two black wires screwed into the old pump.

My new pump did come with some wiring that I had to put together. I don't have a clue where they would go.

Anyone run into this before?

Thanks.

 

 

 

I had the same issue when I made that swap. You need this connector, GM part # 25117765, it runs around $20. Will need to cut off your old connector and attach the new connector.

 

The old connector was the two wires screwed onto the old pump. I spliced the old wires onto the new set of wires they gave me hooked everything back up and it won't start. I checked to see if there was power going to the newly spliced wires before I hooked everything up and there was.

 

Key is out of the ignition and I now have power going to both wires.

 

When the key is turned to the on position I have power going to pump. When the key is off and not in the ignition I have power. It just won't start.

 

I got it started. Must have cross some wires as I burnt out the fuse. Going to get some plastic heat shrink tomorrow and then tie everything together.

My old pump must of been on its last legs. I would never hear it turn on. Once I turned the key I heard the new one. We'll see how it drives and maybe I'll adjust the fpr.

 

On mine i picked up an '86 pump from napa, it came with new wires, plugs, connectors ect.

Some note about the original wiring having issues in the box...

I also one little detail that may help...
I always had issues with my fuel gauge, while i had it out i cleaned up the contacts for the sender, no change right away, however the pump uncovered another issue related to my grounding.

I added a new ground strap to resolve some running issues, but it also fixed my fuel gauge.

 

Interesting. There is a ground wire on top ofhe sending unit that I knocked off last night. It was just sitting there. It doesn't effect the power going to the pump if it's grounded or not.

I'm also going to pull the pump back out and solder the new to old wires together.

 

Well I had it all put in and running for about ten minutes. Put all the bolts back on and now it won't start. Took it out again. I have power going to the pump but nothing happens. I checked the fuse again and it's fine. I don't get it. I had the pump in and running and all I did was tighten so bolts.

 

There is a ground wire that's on top of the sending unit that connects to the main power going to the pump. It must of gotten knocked off when I was putting it back in. Funny thing is that I turn the key to on and the gas gage will move when I touch it to the bare metal on he sending unit. Only some spots. I don't hear the pump or anything else turn on thou.

Any suggestions on what I should do next?

 

Got it running again. Sending unit in with no bolts. Fired right up after I saw that the fuel gage was working. Turned the car off but kept the key to on. If I line the unit up where it needs to be to bolt down the gage stops working. If I shift it up a little it works again. Sounds like I have a loose connection inside somewhere.

 

Got the car running everything seemed to be fine. I went and had dinner last night came back out two hours later. Turned the key to the on position, I could hear the pump turn on, went to go start it and nothing. Lost all power. Sat there for about 5 seconds and the door lights came on. Crank it again and it started. Let it idle for about 15 minutes thinking the battery was dead. Turned it on and off about couple ties and it fired right up. Got up this morning to go and try it and no power nothing, won't crank.


Any suggestions on where to go next with this. I'm frustrated as I feel this job shouldn't of been so hard.

 

I did a rather quick read of the thread and I'd say for starters you need to back up and confirm the condition and the connection of the "pass-through" bulk-head connector at the tank unit flange. That and a good ground of the ring terminal you've got dangling in snapshot will get you likely corrected and running.

 

Thanks. We checked everything last night before putting it back in. Was working fine had it running and cranking over....Even this morning I get in turn the key and zero power. A minute later I turn the power on again and can hear the pump turn on but when I go to crank the car over it's like the battery is dead. I had a mechanic over yesterday who felt the issue stemmed from the fp relay. I did explain that I had no problems with the relay prior to changing the pump.

 

I ain't sayin' this will fix your issue BUT I believe from the quick read that this is where I might consider going with the issues you mention. It's a difficult read because you're "talking mostly to yourself" it seems and that's somewhat confusing by itself.

http://www.racetronix.biz/itemdesc.a...WA-C43&eq=&Tp=

Slow down .................

Do you have the FSM so you can confirm diagnostics at the required relay, connectors etc? Do you understand the FSM?

Can you repair what you've got with the addition of a correct FP51 ACD/ GM# 25117765 as mentioned earlier in the thread? Maybe if you have a pass-through that's known/confirmed good.

 

Sorry about that. I'll break it down.


-Took out old fuel pump.
-Rewired new fuel pump with supplied parts from new fuel pump.
-Put new fuel pump back in. Did not work.
-Checked FP fuse. it was blown. Changed the fuse and car fired up.
-Bolted everything back in and car wouldn't start. But it would crank.
-Pulled pump back out. Checked power to ensure all wires were connected. Only wire that wasn't on was ground on top of sending unit for the fuel gage.
- Pump somehow started to work again. Car was running then stopped.
-Blew another fp fuse.
-Called in mechanic with electrical background.
-He said no power getting to fuel pump.
-He checked all FP wiring and it would turn on no issues.
-Pulled apart FP relay. Looked dirty with some exposed wires.
-Car would start.
-Got in it last night. Turned the key to on, heard pump but everything died when I tried to crank it.
- Let the car sit for 2 minutes and it started no problem. Let it run for 20 minutes and everything was great.
-Got in car this morning tried to turn it on and nothing. Sat for a minute turned the key on and heard the pump. Wouldn't start. After that I couldn't even get the pump to go on.


Again, sorry for the previous posts. It was a very frustrating weekend.

 

The mechanic who I had over last night had a wiring diagram with him. He checked everything over and it kept coming back to the fp relay and the fact that the pump was not getting enough power. When he overrode the relay straight to the fp, it worked fine so he ruled out any wiring issue with the fp.

 

If memory serves me correctly, fuel pump relays were a known weak spot on the '84. So much so that some owners routinely carried a spare.

If you have tech pointing to the relay why haven't you just ran out and picked up a new one?