Onan 5500 generator

I just fixed a similar problem with a new few pump. I also replaced the fuel filter as long as I was at it.

Same thing was happening to my 5500 - run 10-15 minutes and shut down. Codes said there was no command to shut down. Replaced fuel pump and problem solved. Hope yours is just as easy.

Might want to check the air filter, mine would not run, pulled the air filter and very dirty, changed and ran great, mine is at the back of coach, so when going down the road with genny running, picks up a lot of dust. and that was with about 6000 mi on coach, don't know the hours on genny.

BAD Fuel Pump

I had the same problem. It would run 15 minutes and stop after about 10 minutes it would start again and after 15 mins stop again.I unhook the fuel pump and connect it to my car battery and it ran for 15mins and stop. So i replace the fuel pump and problem solve.

Other possibility is overheat.
If your generator is not remembering the codes, you can buy one of those infra-red thermometers and check temperature right after it stops.
Air flow on those coaches can be pretty tricky. I had the issue with my inverter, that was placed mid-ship in storage bay in my conversion and used for AC.
At high speeds it would overheat, but never when rolling in heavy traffic.
Somehow the hot air from rear engine was making it into midship storage bay.

Thanks, my oil level is fine. I am not totally sure but it did stop running after I went around a sharp on ramp. The other times it stopped I think I was going straight down the road.

Your fuel line is now 15 years old. There is a possibility that it has deteriorated to the point it is sucking some air and when under a heavy load the fuel flow is not sufficient.

I had a similar problem with an Onan 7500. It is hard to diagnose going down the road. Like others said make sure oil level is good and plenty of fuel. I found that my problem was the converter was failing to provide 12 volts to the coach. The genset takes 12 volts to run. So look for loose connection on converter and check the voltage out of converter. After I replaced my converter the intermittent problem went away. Your symptoms were just like mine, ran fine at home then problems on the road. Check charge state of batteries as well.

Did you check for codes?

Ours will sometimes stop when we hit a rough spot on the road. Don't know why yet, code just says engine stopped without being commanded to. Fuel nor oil low.