Strange fuel starvation issue solved!

[ohthetrees]

I thought I'd post just in case this ever helps anyone else.


I had a persistent fuel starvation issue that was slowly getting worse over time. Running at low engine power was fine, but I couldn't go more than 6 knots without the engine starving. Fuel was clean, changed filters, and so on. A long time ago I had a fuel starvation issue that came from a bad load of fuel, and I ended up with gunk clogging my fuel selector valve, and clogging the fuel filter housing before it ever got to the primary filter. Rebuilding those parts fixed my previous issue. Naturally my suspicions turned there again, but dissembling those parts again didn't yield the fix...


There was a lot of frustration and trouble shooting, but I finally figured it out. I have plastic tanks, and the top of one tank has become bowed down. You may have seen plastic dinghy tanks that take on a permanent bow, it is like that. As the tank top bowed inward, the pickup tube was therefore pushed down against the bottom of the tank. There is a angle cut into the pickup tube end, but the downward pressure was enough to cause the tip to bend and the tube to bend, making the opening for fuel very small.


Anyway, hope this helps someone in the future googling for fuel starvation issues when their filters and fuel are apparently clean.

[Khaos13]

Wow! Who'd have thought of that? Great catch; I'll file that away in my "2 million things that could never happen" file. Thank you for posting!

[kieranhood]

I haven’t seen the bowed plastic tanks before, it’s seems strange to me that this would be a thing. Do you think that the breather on your tanks could be blocked, creating a vacuum and causing the tanks to deform?

[Nekton73]

Good catch indeed, and thanks for sharing. One more tidbit to tuck away for future reference.


My thoughts immediately went to the breather tube as well.

[Wotname]

Good catch

It is always something!

[Chotu]

Wow! I don’t envy the process of elimination that you had to go through to arrive there. I am very glad you posted this however. Hopefully it will help someone.

I can easily see this happening. My plastic tanks also take on a somewhat unnatural shape.

[Compass790]

Man I could see that causing severe hair loss!

[s/v Jedi]

Note that this was the pickup tube, not the breather getting plugged.

One way I have seen to deal with such problems (plus accumulating water on the bottom of the tank) is to add a piece of flexible hose to the bottom of the (shortened) tube and cut it to a length so that the end is sitting horizontally on the bottom with the hose making a 90 degree bend.