Erratic running A98 engine on atco 14"

[sidevalve44]

My ATCO 14″ with Ally A98 engine is running rather erratically. It starts on first pull, but after a few minutes even if the throttle is half open the revs drop to fast tick-over and then after a few seconds rev back up again. The carb is new (NOS) and adjusting the governor spring makes little difference. When I bought the mower I noticed the fuel tank was quite rusty inside. I have cleaned it up as best I can but, have noticed that the fuel that is entering the carb is quite red looking (despite having an in-line fuel filter). Could this problem be caused by dirty fuel upsetting the mixture ? I have a new B&S tank that I could jury rig if necessary. Appearance is unimportant, I bought it to work.

[wristpin]

If you still have the original fuel tap with the gauze filter, there are now two, the combination of which may be causing some fuel starvation. Try rigging the BS tank on a temporary basis with no additional filtration and if normal running is restored, you have the answer.
Internal cleaning of a rusty steel tank can be done by electrolysis and is very effective. Fill the tank with water with a spoonful or two of washing soda and insert the positive electrode through the filler but insulated from it and not touching the base of the tank. The tank itself is the negative electrode.
It may take upto a week to clean it.

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[sidevalve44]

Thanks Wristpin. That could well be the problem now you mention it. Strangely though, I have another ATCO with Villiers 2T engine that also has 2 filters. The second one that is a red B&S one though, whereas the one on the A98 is one of those clear ones with a little paper filter inside and is probably more restrictive.

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