Fuel pump autopsy....

Chuck Leeper

Toxic old bastard
Staff member
Just did an "autopsy" on a 2 y/o Walbro pump.
BI: 55 Chevy/LS combo. A Tanks Inc tank & in-tank pump, external regulator.
Car sees very little use and sits in a temp controlled garage. Maybe 500 mi/yr.
Pump E10 premium with Stabil added.
Initially, the car would sputter, start, die. Owner pulled fuel filter... Full of what I call "corn starch".
Installed a new filter. Engine starts. Owner heads out for a Sunday drive.... Nope. Back to no start, and the fuel pump lets out it's dying screech and locks up "tighter than a bull's ass in fly time"!
We pull the tank and take a look. DAMN!! What a mess.
Here's some pics.
IMG_1605.JPG

The sender unit gasket. Appeared to be rubber. The fuel ate it up and left it in crumbles. The dissolved "rubber" is all over the
bottom of the tank.

IMG_1606.JPG


This is the interior of the sock. The filter media is totally rotted and crumbles when touched.

IMG_1607.JPG

This is the inlet side of the pump housing.
IMG_1608.JPG

This is the pump pressure plate.
Being this pump is only 2 yrs old I'd think that it would have been built with ethanol fuel in mind.
It's obvious that moisture has been introduced into the system.
Here's a link to the reason the rust is the culprit, and the small engine mfgrs say not to store ethanol fuels for more than 30 days.
Fortunately, this is a NA engine, and quit before the driver was out of the driveway.
Imagine what could happen to your v sicks at 30psi!
 
I wonder how old the gas was. Did it smell old like varnish? You know the smell, kind of waxy and heavy.
 
I wonder how old the gas was. Did it smell old like varnish? You know the smell, kind of waxy and heavy.
Sure did!
The shop still stinks from that stuff.
I got after him months back about the nasty smell in his house garage.
He supposedly pumped the tank, changed injectors, and put fresh fuel in...
 
Does he live in humid area? Methanol is hygroscopic too. I test my meth to be sure it's still in a good range. So far I haven't seen anything below 99%.
 
A
Just did an "autopsy" on a 2 y/o Walbro pump.
BI: 55 Chevy/LS combo. A Tanks Inc tank & in-tank pump, external regulator.
Car sees very little use and sits in a temp controlled garage. Maybe 500 mi/yr.
Pump E10 premium with Stabil added.
Initially, the car would sputter, start, die. Owner pulled fuel filter... Full of what I call "corn starch".
Installed a new filter. Engine starts. Owner heads out for a Sunday drive.... Nope. Back to no start, and the fuel pump lets out it's dying screech and locks up "tighter than a bull's ass in fly time"!
We pull the tank and take a look. DAMN!! What a mess.
Here's some pics.
View attachment 393591
The sender unit gasket. Appeared to be rubber. The fuel ate it up and left it in crumbles. The dissolved "rubber" is all over the
bottom of the tank.

View attachment 393593

This is the interior of the sock. The filter media is totally rotted and crumbles when touched.

View attachment 393594
This is the inlet side of the pump housing.
View attachment 393595
This is the pump pressure plate.
Being this pump is only 2 yrs old I'd think that it would have been built with ethanol fuel in mind.
It's obvious that moisture has been introduced into the system.
Here's a link to the reason the rust is the culprit, and the small engine mfgrs say not to store ethanol fuels for more than 30 days.
Fortunately, this is a NA engine, and quit before the driver was out of the driveway.
Imagine what could happen to your v sicks at 30psi!
Good post
Unfortunately I have seen plenty of this
 
Any chance the fuel was from a gas station that had a flood? I have used E10 in everything for years and haven't seen rubber crumbling like that. I have rubber fuel lines on my snow thrower that's 25 years old and on my lawn mower. Either show any sign of failing. Have they run any other kind of fuel?
 
Any chance the fuel was from a gas station that had a flood? I have used E10 in everything for years and haven't seen rubber crumbling like that. I have rubber fuel lines on my snow thrower that's 25 years old and on my lawn mower. Either show any sign of failing. Have they run any other kind of fuel?
No flooding here.
I suspect the "rubber" was some cheap Chinese shit that is common with about everything these days.
The pump hanger o'ring wasn't affected.
No other fuel ever used.
I built the car from scratch and sold it to him 10 yrs ago.
 
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