Originally Posted by RBC2017
My 2017 ACE 30.3 generator (Onan 4000) shuts down when traveling in hot weather. I think it needs a outside fresh air intake to provide clean cooler outside air . Anyone out there had this problem and solved it? I could use some ideas. I am thinking of a air vent I can open to scoop in fresh air (see photo attached), in hot weather. Then it could be closed in milder temperatures. I would mount this vent in the generator access door directly in front of fresh air intake on generator. Any of your thoughts would be appreciated.Attachment 211466
We have a 2010 Fleetwood Encounter 32bh, which is the same as the Fleetwood Storm models. The generator is located just behind the engine compartmemt on the drivers side and is surrounded by the exhaust system. This creates a lot of excess heat around the generator and since it's air cooled, it adversely affects its performance, especially in hot weather.
Ours in particular would function fine until ambient temps reached at least 90į, we reached a hill requiring the transmission to down shift AND vehicle speed dropped below 50 mph. If all these conditions were present, the generator would die within a minute.
The reason? Vapor lock. The fuel traveling from the tank to the generator would pass so many heat sources, that as soon as it reached the interior of the generator (before it reached the fuel pump) it would vaporize and the fuel would stop flowing. Turns out Fleetwood ran an uninsulated metal tube along the frame rail, above the exhaust pipe to supply the generator.
I have heard of several other motor home that have this same problem and once you wait for it to cool and airflow to be restored the generator would start right up.I
Solutions that were offered include the vent door opening you noted, plumbing an additional fuel pump closer to the tank to pressurized the whole system, adding a fan to force air into the generator compartment, and rerouting exhaust pipes, both generator and engine.
My wife didn't like the idea of cutting a hole in the side of our motorhome, so I installed a marine bilge fan and ventilation ducting from just behind the front grille to the air intake for the generator. It is on the loud side, but between the engine, road and generator noise it can't be heard at all.
It worked fine in temps up to about 100į and I thought the problem was solved. However, we had to travel through an area at a time when the temps reached 110į ! The generator died again within a minute of slowing down on a hill.
When we returned home I used some extra engine compartment insulation to wrap around the exposed fuel line from the tank until it reached the generator. We have had several high temperature hill climbs since and it seems to be solved, but we haven't encountered any 110į temps since then either.
Hope this helps! Sorry for being so long winded.