Sticky needle valves

[rob love]

Just thought I would check to see if others have been having more pronounced problems lately with the carb needle valves sticking. I went to get three vehicles going for an event the other day, and 3 out of 3 had this symptom. With fuel or ether down the carb, the engine would run until it burned that off, but would not maintain. Once I would crack the fuel line at the carb so fuel would reach the carb, then gave the carb a few whacks, everything performed as it should. But even then, a week later, the artillery tractor gets onto the trailer, heads to the display, and then has the stuck needle again. The carrier initially gave me the same problem, but now it's the other way with what would seem to be a wide open valve after sitting for just half a day.

The chev artillery tractor just had its carb rebuilt about 6 months back, the two Fords (carrier and Lynx) have not had rebuild kits into them for at least 4 years that I know of (likely a lot longer on the carrier, although we did dis-assemble the carb last year and re-assemble it after cleaning). Fuel pumps on almost all these vehicles are newer as there have been total failures of them with being parked seasonally, and I suspect incompatibility with the ethanol.

We have the 10% ethanol blend here in Manitoba. A quick google search has many, many hits with the same problem, particularly on outboard motors.

I am going to try a few different fixes as an experiment. I am going to drain the fuel from the tractor, and replace it with a higher octane non-ethanol fuel and see what the results of that are. I may also try some stabilizing additives and see if they help.

Another I will try is replacing the rubber tipped needles with solid brass needles, like the old days. For the brass needles, your fuel must be really clean, and to that end I normally have a larger fuel filter unit before the pump, and a smaller one right at the carb. Rust and debris should not be an issue.

Today’s fuel reportedly has a very short shelf life which is far exceeded by winter here in Manitoba. Several of our vehicles are due to go onto military change of command parades in the next few months, and I would like the operation of these vehicles to be seamless.

So what is the experience of the MLU collective, and what solutions have worked for you guys?