Onan Emerald Plus 5000 won't keep running

Romer1 · 08-06-2007, 12:13 PM

My generator will run fine as long as I'm traveling down the road. If I'm stationary, i.e.at a campsite, it will run for about 5 minutes and stop. It starts up right away and stops after another 5 minutes.
Full gas tank, full oil, new filters and fuel pump, slight smell of gas, like it's running rich.

Any ideas where to look?

Romer1 · 08-06-2007, 12:13 PM

My generator will run fine as long as I'm traveling down the road. If I'm stationary, i.e.at a campsite, it will run for about 5 minutes and stop. It starts up right away and stops after another 5 minutes.
Full gas tank, full oil, new filters and fuel pump, slight smell of gas, like it's running rich.

Any ideas where to look?

gunny · 08-06-2007, 12:35 PM

If it smells like its running rich, it probably is. Deal with that first.

Sounds like it might be over heating.

Are you trying to help it cool by opening the compartment door? That is not a good idea as that door is part of the cooling system, it keeps hot discharge air from being drawn into the cooling air intake.

What are you using for oil? Is it the right weight and not diluted with gasoline, something that happens when they run too rich. Synthetic oil is an excellent choice in air cooled engines.

You aren't overloading it while stopped are you? Added electrical load of water heater, microwave.

Is the engine extremely dirty? Are you storing stuff in the generator compartment that might affect air flow? Not stacking stuff under it on the outside that might block air flow are you? Missing a baffle that diverts discharge air away from intake air.

This is all assuming that this is an overheating issue, a WAG on my part.

tomsm · 08-06-2007, 12:37 PM

Could it be an overheating situation? Maybe the extra cooling airflow while traveling is making the difference. Check for any obstructions to the cooling airflow. Also check your manual - most Onans will give an error code if preemptively shut down.

David K · 08-06-2007, 03:26 PM

If you changed your coolant with the maintance, make sure that you refilled the coolant sufficently. I changed mine and filled the coolant through the overflow location next to the oil dipstick. Gen would start and run and then shut off. Was getting an overheat signal on the error code. Was really puzzled as I would take off the cap and it was full. Read some more and found out that the radiator fill was under the panel next to the start button -- you remove the panel and then under it is the fill for the radiator. After I filled it that way, no more problems. Just a thought.

Sammie · 08-06-2007, 03:31 PM

Try looking at your fuel line. If its rubber it could be cracked somewhere between the generator and the fuel tank in which case it could be sucking air and starving for fuel.

Romer1 · 08-07-2007, 04:24 AM

Gunny,

Doesn't matter if door is open or closed, same result. Oil is Castrol 15-40. Stops even with no load. Engine is not dirty and not storing anything in the compartment.

I think it might be overheating also, but don't know why.

Tomsm, Where would I look for error code.. this is a 1994 vintage.

Sammie, I would think if the hose were the problem, it wouldn't run for 4 hours while moving, would it?

DavidK Not sure what coolant you're talking about???

Clay L · 08-07-2007, 06:19 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Romer1:

Sammie, I would think if the hose were the problem, it wouldn't run for 4 hours while moving, would it?
</div></BLOCKQUOTE>

My Onan 5.5 shut down intermittently. It would usually run while stopped (but not always) but would often shut down while driving anywhere from 10 minutes to four hours.
The problem turned out to be a loose hose clamp where the rubber fuel line connected to the metal line from the gas tank. It was sucking air at that point.

Two dealers and one Cummins/Onan shop failed to find the problem. A tech at the Winnebago factory found it.

tomsm · 08-07-2007, 10:01 AM

Romer1 - I'm guessing you don't have a manual. If it does give an error code the manual would tell you how to read it. Here's a link to Onan's support site that might have a manual for download. Link

gunny · 08-07-2007, 10:13 AM

Tom:
A machine that old doesn't have self diagnostics so no codes.

I'm still thinking overheating. Any way to beg or borrow a thermal infrared gun and see just how hot it is getting before the shut down? I'd shoot the oil filter, see how hot that oil is. Do ti with it stationary and then do it moving downthe road. Well you'd have to stop to do it but you know what I mean.

Also try running the engine when the genset is running, while stopped and see if that makes a difference. If it does, then look for something fuel related.

Let us know.

Romer1 · 08-07-2007, 10:57 AM

Downloaded the manual for this unit. Noticed it said not to overfill oil or could cause shutdown. I think I may be slightly over full, so we'll go drain some oil out. Also will get some new fuel line and see if that helps.

Will also try the engine running suggestion, since it runs well while going down the highway, will be interesting to see what happens when stationary and engine running.

Romer1 · 08-08-2007, 04:10 AM

Ok, here's an update. Drained the oil and refilled with 10W40 making sure I didn't overfill. Fuel hoses were/are in good shape. Started right up , but running rich after about 5 minutes. Discovered adjustment on bottom of carb was wet with fuel so, not knowing anybetter, started fooling around with it. Actually got the fuel to stop leaking and genny ran smoother than ever before. Put a full load (both a/c's) on it and it ran for 10 minutes and died. After that it would only run a couple minutes and die. Did notice the carb was cold to the touch. Internal icing, maybe? Outside temp was 95, humidity was above 89%.

Guess it's off to Onan.

peter griffin · 08-08-2007, 04:43 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Synthetic oil is an excellent choice in air cooled engines. </div></BLOCKQUOTE>

when i check and fill (i beleive it says 2 quarts on the front label..)I always level the rv first.

NeilV · 08-08-2007, 11:52 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Romer1:
Ok, here's an update. Drained the oil and refilled with 10W40 making sure I didn't overfill. Fuel hoses were/are in good shape. Started right up , but running rich after about 5 minutes. Discovered adjustment on bottom of carb was wet with fuel so, not knowing anybetter, started fooling around with it. Actually got the fuel to stop leaking and genny ran smoother than ever before. Put a full load (both a/c's) on it and it ran for 10 minutes and died. After that it would only run a couple minutes and die. Did notice the carb was cold to the touch. Internal icing, maybe? Outside temp was 95, humidity was above 89%.

Guess it's off to Onan. </div></BLOCKQUOTE>

It may be time to take the plug off the muffler and decarbon the unit. With the low decible ratings these are dsigned for the muffler system does load up and when it does could cause overheating and fuel mixture issues.

gunny · 08-09-2007, 01:10 PM

Possible that it is icing but not the first thing I'd look for.

Let us know what Onan finds

peter griffin · 08-09-2007, 03:10 PM

how many hours on this unit and when was the last time you changes both fuel filters and had a tuneup?

Romer1 · 08-10-2007, 05:08 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by peter griffin:
how many hours on this unit and when was the last time you changes both fuel filters and had a tuneup? </div></BLOCKQUOTE>

About 350 hours. Bought MH June '06 and replaced fuel filter, air filter, and fuel pump shortly thereafter. Runs OK as long as we're traveling down the highway, just won't keep running when parked for boondocking/working on inside.

Will be changing plugs next week.

GeneratorJim on RV.net has also given me some things to check. I know the needle valves need some adjusting.

When the humidity = the outside temp (90+), I try to not work on anything outdoors, maybe next week will be better.

peter griffin · 08-11-2007, 08:54 AM

please let us know what happens after the plugs...also how many fuel filters did you change. I know the late models have two. One just to the right of the air filter case and one below the generator...

Romer1 · 08-15-2007, 02:48 PM

Changed the plugs today, readjusted carb needle valves to 1 1/4 turns out from finger tight and started it. Ran best it's ever run since I own it.... for 15 minutes. Couldn't get it restarted.

Must have something to do with it warming up.

Peter... only can find one filter, just off carb

Calling Onan tomorrow, they're about 10 miles away and opebn til midnight.

peter griffin · 08-16-2007, 04:30 PM

i dont have an emerald but the 4000 has two fuel filters and my 5000 gold marquis does so i would assume yours has 2 fuel filters...also, I have learned that if you dont use the generator under a load at least once a month they like to gum up....good luck at onan..