Re: fuel issue or carburetor issue?

Posted by HH56 On 2017/8/20 8:39:30

Assuming it is something fuel delivery related, a few items that have caught others are:

If you have the optional ceramic fuel filter, those can look clean and you can blow thru them but varnish has solidified in the pores to the point that fuel flow is restricted to a trickle.

If the flex hose between the fuel line and pump is old or has been twisted it can have an inner lining that has cracked or loosened. With the suction of the pump it could be allowing a portion of the lining to move and partially block the fuel flow.

In the pump, the bottom chamber contains a screen assy. It can be a mesh screen or stacked plates that need to be disassembled to clean. Tiny rust particles can clog the screen. If the pump is a fresh rebuild that is not likely but if a substitution with an unknown pump then cannot be ruled out.

The vent hole in the gas cap could be clogged or the cap may have been changed to non vented type. There could be something floating around in the tank that is periodically pulled in to block the pickup. That pickup tube opening is nothing more than the end of the tube pointing straight down and positioned about 1/8" or so above a shallow depression on the bottom of the tank. The item could be anything from a chunk of rust or debris to a portion of tank coating breaking free if the tank has ever been treated with a sloshing compound.

If the tank is below half full, one other less likely possibility is the pickup tube could have developed a pin hole at a vulnerable spot at the top of a bend and air is being sucked in.