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Onan Stalling Issue - Gas Tank Vacuum?

reppans
Explorer
Explorer
I own an '08/09 RT170 with Onan 2800 Microlite and had my first repeating stall episode while doing my monthly exercise routine. I *think* it may have been due to a gas tank pressure vacuum, as I had just topped the tank off.

While I was doing the monthly exercise using the Cool Cat AC, my the genset would cut out after 5-10 mins. The engine initially runs smoothly but after few minutes it would start hunting and then quit, sounding much lIke my lawn mower does when I turn the fuel line off. The motor would have a hard time restarting immediately from stall, but wait a few minutes and it was easy to restart. This cycle repeated 6-8x, before I gave up for the day.

The next day, I thought about the potential vacuum issue and opened the RT's gas cap to test it. Genset ran perfectly for the 2hr exercise. Interestingly, I closed the cap at the end of the exercise to see if I could get it stall, but it did not - although to be fair, I didn't wait very long (8-10mins?). Perhaps the gallon of so fuel usage was enough to break the vacuum issue?

Just wondering if anyone else has run into this behavior, or is this a symptom of my Onan fuel pump going bad?
4 REPLIES 4

reppans
Explorer
Explorer
didn't notice any air noises.... will have to check in a few days, we are traveling by air.

thanks for the advice

enblethen
Nomad
Nomad
When you remove the gas cap, does it sound like air leaking or sucking air? If it does not, it could be a bad gas cap.
If you hear sucking then look at the vacuum canister. Should be in front right side near wheel well for a loose vacuum line.

Bud
USAF Retired
Pace Arrow


2003 Chev Ice Road Tracker

reppans
Explorer
Explorer
It's an '08 Chevy Express base vehicle - the short wheelbase RT170 version.

enblethen
Nomad
Nomad
Gas cap issue or the gas vapor problem. The gas tank should vent back through the evaporative canister system.
What kind of chassis?

Bud
USAF Retired
Pace Arrow


2003 Chev Ice Road Tracker