Hissing sound under car near fuel tank after pump install

[kmoore]

Hey guys just a weird question, I just installed a walbro 190 fuel pump about a week ago and everything was fine (noise wise... besides your normal wine) but now all the sudden (today) I noticed a hissing sound near the fuel tank under the car. There are no fuel leaks or cracks in the hoses. And as far as I know there are no vacuum hoses near that area, so I think it cancels that possibility out. But anyway, is this normal or does anybody have any way to fix this? Thanks

 

[Talesin]

Happens with my Walbro 255, though I'm not sure I did the install quite correctly, with the spacer on the bottom for the 1G pump bracket, it was on at a bit of an angle. Hasn't really affected drivability though.

Check your fuel pressure.. if it's good, you probably don't have anything to worry about. Might just not have noticed the hissing noise initially, as you can only really hear it when you're standing at the back of the car while it's running.. not from inside.

 

[kmoore]

So you don't think it's anything to worry about? The car runs fine its just that hissing noise. Anybody else have this issue?

 

[turbosax2]

I took the fuel pump out of my brothers car to verify it was a Walbro 255 and I noticed the hissing sound too when I put everything back together. I didn't notice the sound before I took it out but I wasn't really listening for it. I only noticed it afterwards because I was checking for leaks under the car. He hasn't had any problems with his car either and it runs fine.

 

[mach4g63t]

When I had the interior of my car stripped down to just the bare metal chassis I used to noticed an audible whine out of my stock pump... but only under WOT and boost. Is that normal?

 

[OSXer]

If there is "hissing" under the car, I would check for a fuel leak. If it's from within the gas tank, perhaps the o-ring or some other seal never sealed the pump properly and you're shooting a stream of fuel inside the tank.

When I had the interior of my car stripped down to just the bare metal chassis I used to noticed an audible whine out of my stock pump... but only under WOT and boost. Is that normal?

The whine is probably the result of the pump working harder combined with the voltage dropping. I would require the pump if you haven't yet.

 

[Strm Trpr]

Take the back seat out and remove the metal cover.
There should be a large white ring cap that holds the fuel pump assembly in the fuel tank.
Turn the car on and see if you hear the hissing coming from around this cap.
There is a rubber seal that gets sealed between the white cap and the fuel pump assembly.
If this gets twisted while you're screwing the large white ring cap back on, it will cause an air leak.
I used vasoline on the seal to prevent it from getting bunched up and causing this kind of a problem.
Take a look and get it fixed if this is your problem.

 

[kmoore]

I'm a little confused about when you say "large white ring cap" the only white cap looking thing was on top of the o-ring and that black spacer...

 

[turbosax2]

I'm a little confused about when you say "large white ring cap" the only white cap looking thing was on top of the o-ring and that black spacer...

GST's don't have the white ring cap.

 

[kmoore]

Then that is why I didn't notice it. hahah

 

[CaymanEvo3]

From what i know all high flow 255 walbro pumps make an whinning sound, especially when your fuel tank is near empty. The pump is taking more fuel then your stock pump so it's working harder.


So i guess it's normal nothing to worry about. ps it does it in my Evo 3 also.

 

[kmoore]

When did I say I had a 250 pump?
And when did I complain about the whining sound?

I know its normal for the pump to whine. I'm asking about my 190 FUEL PUMP hissing...

 

[Talesin]

Mine still hisses, and I'm certain that it's not the fuel pump bracket gasket that's doing it, as I've opened the gas cap and gotten a HUGE decompression hiss (moreso than before I'd replaced the pump... better seal get!).

I'm starting to get concerned though about the same thing kmoore is, the hissing IS there (not a whine, a hiss) and it'd make sense if it was the o-ring not fitting quite right... mine slid in extremely easily with just a little bit of spit. Still not sure if it was put on right though, sitting at a bit of an angle like that... especially as it's become increasingly difficult to start in the mornings, though that may be due to a related problem that I'm still diagnosing.

Looks like I'll be taking mine out again and see about hopefully getting a better seal.. not sure how though, unless I get into some creative bending, or toss a few more o-rings on to 'help'. :b