Intermittent Onan Problem

Question

When driving with the 5.5 QD running for the roof air, all or some of the outlets on one leg loose power. Sometimes it is just the A/C that stops, sometimes it is the microwave clock and/or other general outlets.  Usually, stopping the genset and immediately restarting corrects the problem for awhile. It seems to happen more when the weather is warmer. I've had two "experts" trouble shoot this at an hour each and the last one said it was a loose wire at the genset. It was supposedly fixed. It worked when doing monthly generator exercise since February but this week it began happening again when coming home from Phoenix to SoCal. Any ideas or suggestions out there. I have a service appointment with the last place that supposedly fixed it and want to be armed with some suggestions. Thanks in advance.

twomed · Answer

Fuel lines that are cracked or loose at fittings suck air and give this problem.  Low fuel pressure from a weak/failing pump do also.  AND if fuel related it will cause fault codes that say change electrical parts because the engine never gets up to speed or can't sustain a load.  Parts changer type techs will change all those part$$ and you will still have a fuel related problem.  Good luck...intermittent stuff is always harder to fix. :)  :)

cochise49 · Answer

No fault codes are displayed. I will suggest a fuel line/pump problem though. Thanks Twomed.

wolfe10 · Answer

If a fuel line issue, the generator will not continue to run smoothly.

Does it continue to run smoothly and continue to produce proper voltage on some circuits? If so, it is not a fuel line issue.

If the generator surges and/or voltage fluctuates, it very well could be a fuel line issue.

If fuel line issue is suspected, run the generator from a 5 gallon container of diesel direct to the generator fuel pump. That will eliminate the fuel line as a cause.

big_buford · Answer

Weak transfer switch? Few months ago poped the cover off mine and found a couple lose wires. Almost seems to me when they use wire with few conductors/strands they settle a bit and need to be retightened. Easy to check.

mexicowanderer · Answer

Start with the obvious. Things that "loosen" can loosen again, and again, and again. Hope it wasn't a mechanic who did little if anything, went home and prayed it wouldn't happen again for while.

Beware of loose anything that can cause overheating and a fire.

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Intermittent Onan Problem

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