Buick lasable Fuel Pump

I changed a fuel pump that a service shop said was bad. It would start and run for a few minutes and then stop. If it started at all. I dropped the tank and put a new pump in. The car did not start at all, not once. Not even fire. I had to install a new electrical connector inside the tank on the pump. The connector was different than the one in there. I connected black wire to black and grey to grey, thinking that made sense. Took off inline fuel filter next to tank. Had someone turn on key to see if fuel would come out. Nothing. But I did hear fuel running loudly through the return line. Which confused me at the time.

Thinking of it over night, could it be not likely, very likely those lines are in reverse, causing the pump to pump backwards. Which is why I heard fuel going through the return line? If this is the case I am going to try tomorrow to reverse the lines going into the tank. Instead of the fun of removing tank again.

What are your opinions on this. Why would pumps have black and grey wires that hook up differently? Do they? Anyone have this problem before?

Don’t know if this will help but I installed a new in tank fuel pump & could hear the pump running but had a no start problem . Outside the tank there was two rubber fuel hoses that connected to the pump/tank & the other ends connected to two metal lines that ran toward the front of the vehicle . I mistakenly crossed those rubber hoses when I hooked them back up .

I suppose the wire polarity could be reversed but since the wire colors matched it seems unlikely that is the trouble. The post that @Sloepoke wrote and talks about the reversed hose lines makes a lot of sense.

I did not remove any hoses besides the one that holds the filter.

Do not some pumps come with different polarity? Since then would they not have the same color wires, just the polarity would be opposite? I do not know for sure, but it seems possible at least.

Okay. Since you didn’t move any hoses then reversing the wires should do the trick.

Do you have a schematic of the pump circuit? Are the pump terminals labeled with numbers on the case of the pump? Might be able to resolve the wiring connections that way.

Sounds like you have the wrong pump.
Can you get the right one? My next move would be to do that, get the correct connector, and reconfigure everything back to stock. I never butcher wire harnesses because it far too often doesn’t work.

I don’t understand how you could replace the pump and not have disconnected the fuel lines.


I don't understand how you could replace the pump and not have disconnected the fuel lines.

It would certainly explain why the car didn’t start after the job was done. :wink:

“Instead of the fun of removing tank again.”

Model Year?

Is This Car Really Old? The LeSabre Models That I’m Familiar With Have A Fuel Pump Access Cover In The Trunk. No Need To Remove The Tank.

Access cover? Slaps forehead.

My feeling is that if I had a GM fuel pump go, I’d trade cars. I’ve had more GM fuel pump problems. Two out of the box no good. One lasted a week. Another couple a year to the week. Replaced pig tails, relay, wiring etc. and still problems. Can’t remember how many times my two Rivieras were towed due to fuel pumps. Used to carry a 5# hammer, a test light, and fuel pressure gauge in the trunk just to quickly diagnose.

At any rate, back to square one and check your work. Pig tails need to be replaced as well as the relay so that you don’t wreck another pump. My understanding is that you can’t bench test the pumps dry without burning them up but I’d start with a good look at the service manual.

Replacement in tank fuel pumps are one area where I wouldn’t cheap out. I’ve heard too many nightmares about after market fuel pumps. As far as GM in tank fuel pumps are concerned my last seven cars have had them and only one failed and that was at 267,000 miles.

Also, it was mentioned in a post above that there in as access cover in the trunk for the fuel pump. Isn’t the tank mounted ahead of the rear axle under the back seat? Correct me if I’m wrong.

Many GM cars have a fuel pump test plug under the hood. This is a single small wire with a tiny female connector. A jumper wire can be run from the battery positive terminal to that plug and the pump should operate. It’s usually located on the passenger side near the firewall and ECM depending upon year model.

This is a test plug only. It is not meant to remain connected.

“Also, it was mentioned in a post above that there in an access cover for the fuel pump in the trunk. Isn’t the tank mounted ahead of the rear axle under the back seat? Correct me if I’m wrong.”

Those trunks are rather voluminous, measured is sets of golf clubs! The access plate, if there is one, is located forward and to the right of center of the spare wheel well, almost to the back seat, way up there. You just about need to camp out in there and get comfy to work on it.
Picture an open rear door and the tire behind, to get an idea of proximity.

Also, I concur, in hundreds of thousands of miles on GM cars I’ve never had a fuel pump problem. Fuel sender (on the pump) ? Yes, one.


I think that @knocksensor has either figured it out,or he’s not talking.

It doesn’t make sense that he pulled the fuel filter and when the pump was energized, he could hear fuel being pumped back to the tank from the return line. With the filter disconnected, where is the return line getting fuel from.

I wonder if he had something other than the filter disconnected.

It would be nice to know what year beast this is.


I didn’t disconnect lines because I changed it under the car. It turns out it was connected right. I took the tank off again and tested it and it worked. Put everything back together and it would not start. Had 5 gallons of gas. I then put the jack in the front of car to push the gas to the back of the tank and it started and ran fine. And it kept running for a long time without stalling. Filled tank and took for test drive. Car ran fine.

It is a 98 and the tank is under the back door in front of the back tire.

Having 5 gallons of gas in the tank should be more than enough to supply gas to the inlet of the pump. It sounds like the pump isn’t seated correctly in the tank to pick up the gas.

It makes no difference @knocksensor weather you pulled the pump out and took it to a bench, changed it under the car, or held the car up with a sky hook to change it. The old pump had to be disconnected from a line somewhere.

It is a pump!
It pumps fuel!
You remove the old pump and there is an open line, until you put the new pump on.