I just replaced my fuel pump on my 97 Blazer 4dr.
Truck runs fine.But I notice a thumping noise that occurs about 5 seconds after I turn the engine off.It sounds like the tank pops.
I believe it's from the pressure being released in the tank.

Any ideas ????

As stated,,everything works ok.

 

HA! I just posted something about this, is it like a low metalic ding? just one time? Mine does it when I start the Truck and again a few mins after turning it off.

 

More like a plastic pop bottle thump.No metallic sound.And it's only after I turn it off.

 

Yeah, I guess that could be another way to describe it....but yes I believe its the same thing....Someone else on here said it sounds like its just making noise when expanding and contracting from the heat.

Mine does not do it all the time....some times only when turning it on, sometimes only when turning it off....never regular.

 

Just replaced the gas cap also.But it still makes the noise.I guess next step will be too drop the tank again and check the vent on front of tank ????

 

The noise still persists after the new gas cap.
Check engine light has been on all week.Today as I was sitting at a traffic light I heard the thump and the light went out.After I got home and shut it off,it did not make the thump again.

I'm still trying to figure out what caused this to begin with..
Seems the pressure in the tank is not being released correctly and only releases after the fuel goes back into the tank after shout down.


ANYONE ????

 

I replaced my gas cap, did not do anything....whats your code say? have you checked?

 

Did you guys get this figured out? Vent valve? Carbon module? I didn't sweat it for years, until my fuel pressure went goose-egg on me. Can't help but think the two problems (as well as gas pumps cutting off on me at a quarter tank) are closely related. Solution? Anybody? Swartlkk?

 

Did you have any luck finding reason for this issue? Our 2000 Blazer does same thing.mwirhin minutes of shutting it off, there is a pop sound from tank. Almost like a rapid pressure change causing the sheet metal to pop on the tank. Also, my gas gauge is not working properly. I'm thinking they are related.

Thanks,

 

I totally forgot that I posted the problem on here,, hence the new name.

The problem was the fuel tank vent valve located on top of the tank near the front.
It has been doing this since I put the Airtex pump in it.

I finally had to drop the tank due to a pinhole leak in the tank itself.
I replaced the tank and the vent valve and the popping has not occurred since.

Be carefull when putting the new vent valve in.After I got the hose on it and was lifting the tank, the front slipped down and the tip of the valve broke because the hose was short..Had to get another one.So I bought a new longer hose for on it and routed it so there were no kinks.

So far everything seems ok.

Side note:
I also had a hesitation when going up a hill like it was being starved for fuel.
That problem has went away also.So the 2 symptoms were most likely due to that vent valve.