Onan Microquite 4000 adjustments question

[rpgibbs]

I have an Onan Microquite 4000 Generator in my 2008 Lexington RV and need some advice in adjusting the idle speed etc. How many adjustments are there on the generator? I have replaced the air filter and the spark plugs with Onan parts. The generator runs but is constantly surging (changing speeds) and I need to know if there is a fuel/air rich adjustment screw somewhere on the front of the generator. Any other suggestions would be appreciated. Thanks

[lbrunning]

does it do this under load or not or both?

[rpgibbs]

It does it both under load and not under load but is much more noticeable when it is NOT under load. What do you suggest?

[lbrunning]

the only adjustment on the carb is the altitude adjustment witch is a air fuel adjustment. remove the cover on gen set and you should see it. the screw directly under it is the drain valve for the carb. the other thing would be when is the last time the fuel tank was filled. with the poor quality of gas these days it only takes a couple of months for it to start to go bad and will effect small engines. i use seafoam in mine it will clean out any varnish deposits.

[WTA]

I had the same problem with my Onan. I ran it every month but the carb still gummed up. Seafoam did not solve the problem. Buy a new carb and switch to pure gasoline if you can find it.

[TURBS]

Remove the carb and clean all passages.
Don't use ethanol.
If you have to use ethanol use startron.



Turbs

[WTA]

Another related problem with my Onan which was mounted in a KZ toy-hauler had to do with a check valve on top of the gas tank. I went through a couple fuel pumps before I discovered the fuel just would not come out of the tank which was mounted behind the rear axle, generator up front. The problem would occur randomly. The fuel pump would start rattling and then the generator would quit. Sometimes it would start back up immediately. Sometimes it had to set several hours before it would restart. Finally there was no fuel flow at all. Had to empty the tank and drop it. The check valve was a ball and spring affair that finally stuck completely closed.

[lbrunning]

part of the problem with generators is we do not run them enough or hard enough. it is hard to get a good cleaning with sea foam in a motor home when the gen set pulls fuel out of the main fuel tank . sea foam says one pint to 8 to 25 gallons if you have a 50 gallon tank that could be up to 6.25 cans of sea foam. the best running gen sets i have seen have been ones that are worked hard and have used any fuel additive on the lines of startron, sta-bil or sea foam on a constant basis .