SNAPSHOT Report post Posted March 29, 2020 I have a 2011 Phoenix Cruiser class C. Generator is an Onan 4000. It starts, however when I remove the load, it stops and will not start until the next day. Just got it back from the RV shop. They put a new circuit board in. The hour meter reads 38 hours. RV mechanic said seems to have many more hours on it. Checked the original papers and the generator serial numbers. They match. Talked to the previous owner who said he rarely used the generator. Just got new Trojan AGM batteries. The previous ones where reading 12.8 volts but a specific gravity test indicated they were no good. Thanks for your input, Steve Share this post Link to post Share on other sites
wolfe10 Report post Posted March 30, 2020 Steve, Welcome to the FMCA Forum. If that 38 hours in 9 years is anywhere close to accurate, a VERY high likelihood that the carburetor is gunked up and needs either an overhaul or replacement. Share this post Link to post Share on other sites
f442485 Report post Posted March 30, 2020 I had an issue with a customers generator about a year ago. The issue was the owner only used the gen-set to charge the batteries. It had excessive carbon deposits on the pistons and valves. We cleaned the carbon out and ran the generator for about 3 hours with a heavy load. We had the a/c on and two(2) commercial battery chargers plugged in and only got to 75%. The issues were corrected and the customer now loads the gen-set every time he starts it up. Hope this helps. Share this post Link to post Share on other sites
SNAPSHOT Report post Posted March 30, 2020 20 hours ago, wolfe10 said: Steve, Welcome to the FMCA Forum. If that 38 hours in 9 years is anywhere close to accurate, a VERY high likelihood that the carburetor is gunked up and needs either an overhaul or replacement. Thanks for your reply, Wolfe. The generator runs fine under a load. So that tells me the carburetor is ok. Am I correct? The generator stops when I take the load off. Yesterday, I started the generator. It ran fine. Turned on the refrigerator, hot water heater and the heat strip. Generator ran fine for an hour. Decided to turn off the hot water heater. When I did, generator stopped running and would not restart. Share this post Link to post Share on other sites
kaypsmith Report post Posted March 30, 2020 12 minutes ago, SNAPSHOT said: The generator runs fine under a load. So that tells me the carburetor is ok. Am I correct? The generator stops when I take the load off. Yesterday, I started the generator. It ran fine. Turned on the refrigerator, hot water heater and the heat strip. Generator ran fine for an hour. Decided to turn off the hot water heater. When I did, generator stopped running and would not restart. Maybe more of an indication that the carburetor is the problem, under load runs fine, the carburetor maybe over fueling and causing a flooded condition, choke may be sticking, or the float/needle/seat assembly may be the culprit. 4000 gensets that I have worked on in the past had issues with flooding, float was nearly always the problem. Forgot to mention that under heavy load the genny is calling for more gas. Maybe as simple as the idle screw is out of adjustment. Share this post Link to post Share on other sites
wolfe10 Report post Posted March 30, 2020 I have NOT worked on an Onan carburetor-- but have on lots of other one barrel carbs (think Solex, SU, etc). Very likely the idle circuit is different than the load circuit-- at least they are different on automotive carbs. Hopefully someone with hands on Onan carb experience will chime in. Share this post Link to post Share on other sites
huffypuff Report post Posted March 30, 2020 Cummins don't supply kits for their carbs anymore. The last carb I brought for small engine was $12 on ebay. Share this post Link to post Share on other sites
kaypsmith Report post Posted March 30, 2020 55 minutes ago, wolfe10 said: have NOT worked on an Onan carburetor-- Most were tillotson, or carter. same principle as the ones mentioned by Brett, although they all use an electric fuel pump, maybe as simple as a fuel regulator, I've changed those out before.. Share this post Link to post Share on other sites
rls7201 Report post Posted April 3, 2020 On 3/30/2020 at 4:10 PM, SNAPSHOT said: Thanks for your reply, Wolfe. The generator runs fine under a load. So that tells me the carburetor is ok. Am I correct? The generator stops when I take the load off. Yesterday, I started the generator. It ran fine. Turned on the refrigerator, hot water heater and the heat strip. Generator ran fine for an hour. Decided to turn off the hot water heater. When I did, generator stopped running and would not restart. The carburetor did NOT return to the idle circuit when you removed 1/3 of the load but remained on the main circuit. So your fuel mixture is OK. What could be happening is the carb is not throttling back when you remove the load and the generator is shutting down due to over speed (high frequency). Clean and check the throttle linkage for crud buildup and binding. If you have a kill-a-watt meter, look closely at the frequency setting when you remove the load from the generator. Onan did not use a fuel pressure regulator on its RV gas generator. Richard Share this post Link to post Share on other sites
dickandlois Report post Posted April 3, 2020 Thanks, Richard! The original poster might want to make sure the throttle return spring is in place , not damaged or disconnected. Brake cleaner work well, but make sure there are no ignition points. Like electrical switches being used or any other item that could ignite the vapors.. Any cleaning agent is flammable when the mixture is right. After cleaning the area lubricate the privot points with silicon or PTFE spray combination. Everything should be free and spring back to the Low Idle point. Rich. Share this post Link to post Share on other sites
