Onan 5500 surges and dies after 20 minutes, sat all summer with ethanol gas

surge then shutdown on an HGJAB that sat with old E10 is the carb nine times out of ten. the idle circuit varnishes first, so it runs ok until it warms up and the mixture leans out, then it hunts, then the governor gives up and it shuts down on a code. check the code first though. with it stopped, press the stop button and the status light blinks the code, count the blinks. code 36 is engine stopped without command, which is what a fuel starve looks like from the controller's side.

for this weekend: fresh 93 in the tank, half a can of seafoam, run it under load for an hour. sometimes that clears a light varnish. if it does not, the carb comes off, it is about 8 bolts and the choke linkage, and a new one is around 90 to 110 bucks aftermarket, more from cummins. do not try to rebuild it, the jets are pressed in on that carb.

also check the fuel pickup. most haulers cut the generator pickup tube so it stops drawing at about a quarter tank, so the truck can still fuel up and get home. if your gauge is lying you might just be low.

had the same thing on my 2020 Momentum with the 5500 after it sat through the winter. seafoam did nothing. new carb from amazon for 95 dollars, an hour on a saturday, has run every weekend since. change the oil while you are in there, mine had never been changed at 140 hours and it was black as the gas.

one more for the list since i just went through it. the fuel filter on the HGJAB is a little inline plastic one under the generator cover on the inlet side. mine was brown. 6 dollars. if you are replacing the carb anyway do it, otherwise you are feeding the new carb through the old filter. and put stabilizer in when you park it. i know everybody says it. i also did not do it and it cost me a carb.

we get this one every september so i am leaving it near the top for a while. brush country, post what the new carb did so the next guy knows if it was worth the hundred bucks.