!! - 89 Fuel Tank / sender electrical question - !!

[unstable]

if anyone has any insight here I would appreciate it.

When I dropped my tank I couldn't really see to the top of the tank and I was doing my best to disconnect lines and everything blindly.

electrical
There was a dongle with what I think is a 3 pin connector on it coming from the harness to the sender. I disconnected this badboy and it felt like there was an additional wire going to the frame. I traced it with my fingers and it was indeed going to the frame and it was held in by a rusty screw. I couldn't tell if this was factory or what, but I decided that the screw wasn't going to come out under those circumstances and I needed to just snip the wire.

Snipped.

After the tank came down I notice (maybe it was white) wire that was tucked into some electrical tape that was wrapped around the wires going to the sending unit...the wire didn't appear to be attached to anything on the sender side...I assumed that the opposite end was going to ground...I pulled the wire out of the tape and tossed it aside...figuring that it must have been some garbage left over from some other job at some point.

Well I put the tank up last night and she's not starting...I'm assuming that I kind of need that ground strap, but I'm not 100% positive and I don't want to blow myself up

The sender sits in a rubber ring so it's somewhat isolated from the tank...I checked the wiring diagram and I'm not an electrical engineer but it looks like the tank is grounded somewhere..

do I need a line from the top of the sender to the frame?...any insight is greatly appreciated.

 

[unstable]

I hath discovered the problem...
the sending unit has 3 wires that goes into a connector that ties into the harness on the frame...there is one additional wire off of the sender that goes to the frame/ground...in my case, the wire had broken off flush where the wires go into the sending unit down into the fuel tank...

awesome.

 

[unstable]

the saga continues

Last night I thought about this minor issue of that wire being broken off. I cursed the GM engineers a little because I don't understand why that ground wasn't part of the weather-proof connector, but I guess in the end that it doesn't make too much of a difference.

I had a few options...I could have tried to repair that wire even though it was broken off flush...I didn't like this approach because I honestly am not a fan of the fuel pump being inside of the tank anyhow. Plus with plans to replace the whole TBI with a carb in the near future, I'm going to have to do some modifications to the fuel system anyways...

I settled on picking up one of the Holley Blue electric fuel pumps...I almost went ahead and bought the relay and all of that other stuff along with it but I started thinking that I can probably tie into the existing harness/connector and be good to go...which is what I'm going to try. If anyone has any advance knowledge / wisdom that they wish to impart on me before I go making things worse, please let me know.

 

[unstable]

I got this from another forum with my question and I hope that this helps someone else...

The fuel pump wiring is a little unusual on these trucks. The relay only powers the pump when the engine is being cranked. This relay is only controlled by the ECM. This is how the pump turns on for two seconds before you have oil pressure.

Once oil pressure closes the switch, the pump is run directly through the oil pressure switch, bypassing the relay. The relay is de-energized by the ECM after two seconds and does not close again until the next time you start the truck. Both of these circuits are connected together at the pump, so you can simply wire the Holley pump in place of the stock pump with a single wire connection. The other wires to the sender are for the gauge.

 

[Fast 95]

Send the Holley pump back, i had a red pump that lasted for about a year, went to the blue pump and it lasted a whole 8 months or so. If you are going carburated, use a mechanical pump IMOP. I'm only suggesting this cause i have been where you are about to go, but i went with aftermarket gauges so the only wire i used from the harness was the level sending wire.

 

[unstable]

wow that sucks...Holley's Q&A must be crap now
Problem is that I'm in somewhat of a limbo-area where I have the existing TBI / ECU controlled advance dizzy and any repairs that I'm trying to make, I'd trying to make provisions for the motor swap in the future.

I thought those fuel pumps were warrantied at least for awhile...did you have any trouble with that? I do agree though, mechanical fuel pump would be fine if I had a carb right this second

 

[Fast 95]

I dident even waste my time with a warranty, I had 2 of their eletric pumps go bad my self, i have several friends that have had the same outcome and went through multiple pumps. I wanted to get away from them all together.

 

[DRAGGIN95]

Why not keep the in tank pump with the carb, and run an adjustable regulator at the engine? I have personally had many different mechanical pumps fail as well, I also have ran a red holley, and they definitly don't last.

 

[unstable]

I hate the design of the pump in the tank...dropping a gas tank is a pain in the ass, especially if it's full of gas. Say you had 20 gallons of gas in your tank and your pump failed...you're going to have to pump out 4-5 gallon jugs of gas out of that thing to drop the tank...that sucks.

Despite the warnings with the Holley, I went ahead and re-plumbed everything and got rid of the in-tank pump. I have to go back through and tighten up some fittings and she should be good (at least until the Holley fails)...With the cost of those pumps I'm surprised you didn't warranty them.