I have a 96 blazer 4.3 4x4 4dr. I just replaced the fuel pump about a week or so ago. Drove fine for a few days then I got the P0440 code, cleared it and hasn't come on in a day. The truck rides and accelerates fine but, I noticed now with the new pump my gas gauge will swing about a quarter of a tank either way depending on if I'm braking or accelerating. I have a half a tank right now and haven't completely filled it yet since having the pump replaced. Any ideas? I replaced it with a delphi pump. Anything will help at this point, it has 195k on it and I'm trying to keep it mechanically sound but I'm unemployed and don't have a bunch of money. I can't put it in the shop and let them fish around or buy this part and that part right now. Thanks in advance.

 

Sounds pretty normal to me, unless your being conservative on the amount of needle sway. hope it helps!

 

Did you replace the wiring connector when you installed the new pump? Sounds like you are having a connection issue.

The fuel pump sender signal should be conditioned to take out any fuel sloshing effect when braking or accelerating. If the sender ground or signal is dropping out at any point during these events, it would be a significant change in the signal back to the PCM which would cause a noticeable difference in the gauge reading.

 

Yes, the new pump came with the wiring harness. I went out and took down my spare and checked the plug on the top of the pump, it seemed a little loose so it may not be plugged in good. I didn't see any pinched wires, I am going to get a better look at it tomorrow and see if I can't make sure it's plugged in properly. The gauge does sway a full quarter of a tank and wasn't that bad before so it may be something with the new pump installation.. I'll post any findings. Thanks

 

What brand of fuel pump did you install? On my 96 it had an Airtex pump that someone had put in it and the swing was horrible. It could not make up its mind on what to show. I ended up having to replace it when I took out the fuel tank to look for a leak, and I used a AC/Delco pump and now it just has a small amount of swing to it. Which is normal for these vehicles. Also the old pump was so noisy it sounded like it was going to take off.

 

I put in a delphi pump, I had heard bad things(read the threads on this website) about the Airtex pumps so I made sure I stayed away from them. The pump is pretty quite, the original made more noise on start up.

 

i just installed a delphi (after buying a used pump and a new cheap pump that were both dead) on saturday and i was noticing the same thing. but hey, i'd rather have a swaying gauge than a dead blazer. must just be a delphi thing

 

Yeah it's not a big deal, but if there was an easy fix for it... and if I figure something out I will post it. Thanks for the info though, atleast I know it's not just mine.