Another B&S Engine mystery.

[SARG]

I have a Husqvarna 2354GXLS tractor with a B&S engine. Yesterday I changed out the transparent in-line fuel filter. Today I used the machine for about an hour without any issues. Before I put the machine away I lifted the hood from the seat to double check that the new filter was not leaking.
I was surprised to notice that the fuel within the transparent filter looked like it was boiling ......... a multitude of "air bubbles" were entering from the tank side.
I have never noticed this before and now I wonder if there is an issue I should address.
Has anyone else noted this on their engines ?
I'm suspicious it might be heat related.

 

[LittleBill21]

if your not having a issue leave it alone. My mower has the gas tank above the engine. I have literally seen the gas boil on a hot hard load day, that was 8 years ago and I still haven't needed to do anything.

 

[SARG]

I just got back into the house. I can never leave anything I don't understand alone.
I replaced the spring action clamps with some worm drive to eliminate possible air intake and also wrapped the fuel line were it is near the engine components with a length of split ¾" pipe insulation.
Time will tell.

 

[oldnslo]

Was the engine running when you looked at the filter as saw the bubbles?

Where is fuel tank in relation to filter and fuel pump?

Reason for asking is that some of the lower cost filters I have seen had a pretty large seam from mold process that could allow air to leak past especially if pump is lifting or drawing fuel through the filter. Your worm clamp could solve that problem.

 

[SARG]

Machine was running & the fuel tank is in the rear over the tires.
Lots of mowing required tomorrow so that should tell if I've made any change.

 

[sd455dan]

I have a Husqvarna 2354GXLS tractor with a B&S engine. Yesterday I changed out the transparent in-line fuel filter. Today I used the machine for about an hour without any issues. Before I put the machine away I lifted the hood from the seat to double check that the new filter was not leaking.
I was surprised to notice that the fuel within the transparent filter looked like it was boiling ......... a multitude of "air bubbles" were entering from the tank side.
I have never noticed this before and now I wonder if there is an issue I should address.
Has anyone else noted this on their engines ?
I'm suspicious it might be heat related.
View attachment 810649

I had a Volvo Penta Boat engine do that but it was caused by aged fuel line,

The engine used a mechanical diaphragm style pump but had to draw through the tank one way valve which was in the front of the boat.
Boat ran great for a few years but started seeing bubbles in the clear test filter I put on when the boat started needing extended cranking to start.

I started looking very close at the 16 foot fuel line which was pushed up against the carpet under the gunnels. and noticed "dark" spots every few inches in the carpet.

At that point I did a vacuum test on the line itself and sure enough it would not hold a vacuum.

Installed new marine fuel line and the bubbles disappeared as did the extended engine cranking then reinstalled a metal cased filter.
Just another way the fuel can appear to boil- but is not a heat related boiling of the fuel.

 

[WranglerX]

I has similar "bubbles" while engine was running (B&S powered mower) .... Engine was also miserably hard to start.... Found bad fuel line between tank and filter... It had microscopic holes that would allow air into system but were not large enough to show as a fuel leak.... It was all about the size of the molecules of fuel vs air....

 

[tomplum]

You should really replace those barbless filters. Doom, despair and agony they will bring. Trim the line to get a good seal.

 

[Egon]

Chances are a vacuum is lowering pressure and gas is evaporating.

 

[SARG]

You should really replace those barbless filters. Doom, despair and agony they will bring. Trim the line to get a good seal.

Perhaps ....... But I've been using them on five machines without issue for a couple decades until this mystery.