Generator wont stay running

[dennis1492]

My generator which is a 4K Onan genset which I bought and installed in my MH will not stay running? I installed a electric fuel pump which is 2.5 pressure, The gen. will start run maybe 45 seconds then the carb, will try to rev like the governor is surging but it dies, does anyone have any idea what I might try to get the thing running? Is there a spring in carb. that controls the governor? I have over 1/2 tank of gas and if I take the gas line off and crank the engine I get gas comming out, I put sea foam in tank and also whil it was running I sprayed carb. cleanner in breather and when it started to die I would spray more cleaner in and it would keep running?Any help would be greately appreciated.
Dennis

[RickO]

Hi and welcome to the forum.

Sure sounds like it's starving for fuel but I'll let our experts chime in on this one.

Best of luck.

Rick

[fire8033]

I am having the same issue with my generac Generator. It fires up and runs great for all of 30 seconds to a minute then dies. Seems to be getting fuel.

[jimmyjnr]

Fuel filter ? Just a thought ,

[Senior Chief]

First I would check/change fuel filter and fuel hoses. The hoses may be collapsing or split and sucking air.

Next would be to check the fuel pump.

[Chaffeekid]

Hey Dennis, what year is it? Does it have electronic ignition or does it have points and a condensor? If it does, my brother had the same problem, and I opened the points to about the thickness of a match book cover, (old Harley trick) and it settled down and ran fine.

If you check on the web you will find a lot of information on the generators. If it is a Onan, what model number put that in a search engine and you should come up with some info.

The points on my brothers was operated by a pushrod system and set in a little cover behind the carb if I remember correctly.

Hope this helps
Happy Trails
Jim

[mgscott4]

Try this,

Get a few feet of fuel hose and attach one end directly to the fuel pump inlet and the other end into a gas can with gas in it. If it runs off of the new fuel source then you know the problem is toward the tank and not the generator. If it doesn't then troubleshoot the generator.

[bjsheldon]

Had a similar problem. After several phone calls with an Onan gen engineer, I found out Onan had a problem with their fuel pump supplier. The suggestion above is a good start. Try running the generator off a can of fuel using a line from the fuel pump to the can of fuel. If it runs OK the problem is in the fuel system to the main tank. Remove the fuel cap and try blowing air thru the line to the tank. If the above doesn't solve the running problem, support the external fuel can ABOVE the carburetor and connect the fuel line directly to the fuel filter, If the gen set runs its the fuel pump, if not its the filter or something internal to the genset. Hope this helps. Remember gasoline is extremely flamable so be careful.

[jimbo16720]

Originally Posted by Senior Chief

First I would check/change fuel filter and fuel hoses. The hoses may be collapsing or split and sucking air.

Next would be to check the fuel pump.

Hoses was my problem. When I bought mine it would start and surge. It had a shutoff valve in the line and it was to small for the size hoses on it. I could spin the shut off valve inside the hose. It was sucking air around the valve.

[clyon51]

Originally Posted by fire8033

I am having the same issue with my generac Generator. It fires up and runs great for all of 30 seconds to a minute then dies. Seems to be getting fuel.

Generacs are really finicky when cold. The start button is also the choke. After the engine starts, leave the button held down for 10 sec or so and you may have to do this twice or hold it down longer. There is a sensor that disengages the starter when the engine exceeds starting RPMs. I'm not saying this is your problem, but could be. Most Generac owners are not aware of this "feature".

If you are still having problems, start a "Generac" thread.

[dennis1492]

Hi All
Well these are all good sugestions, I put a new fuel filter on along with the new fuel pump, but it has another filter inside the case which I didn't change now with the line off the carb. and the fuel pump turned on no gas comes out but then crank the gen. over and gas comes out? does this sound right? Guy here in Bradenton told me since it has sat for a year that the carb. needs to be taken off and cleaned as the jets probally are gummed up and dirty does this sound possible? I guess anything is possible with mechancial stuff

[Wolfpack Fan]

Originally Posted by dennis1492

Hi All
Well these are all good sugestions, I put a new fuel filter on along with the new fuel pump, but it has another filter inside the case which I didn't change now with the line off the carb. and the fuel pump turned on no gas comes out but then crank the gen. over and gas comes out? does this sound right? Guy here in Bradenton told me since it has sat for a year that the carb. needs to be taken off and cleaned as the jets probally are gummed up and dirty does this sound possible? I guess anything is possible with mechancial stuff

I was having trouble with my Onan 7k when we first purchased our mh. It's good now, but it drove me crazy till it started running right. With mine I ran some Marvel Mystery Oil through the gas tank and it cleared up the stumbling intermittent engine miss I was experiencing. In the process I spoke to a Onan technician at a RV repair shop and he told me Onan carb is very sensitive to sitting without running for extened periods and the carb will gum up easilly. In the process I also got on just answer dot com and worked with a certified Onan technician. I think I paid less than $20 for the expert advice. Here's the final answer he gave me, copied and pasted. Maybe it can help you.

First, let's see if the set has given a fault code.
Go to the genset and use the switch on the set itself.
Press 'Stop' 3 times within 5 seconds. The light in the switch will start flashing.
If the light flashes 3 times, pauses for 3 seconds, and flashes 3 more times, press and immediately release 'Stop' one more time.
This will put the controller into Fault Read Mode.
The light will flash (X) number of times, pause for 1 second, and flash for (X) number of times again. Count the flashes before and after the pause.
This will be the Fault Code.
Example: flash, flash, 1 second pause, flash flash flash flash flash is a Fault Code 25.
There may be more than one Fault Code stored, so watch the light very carefully. If there is more than one code, it will display them all in order, and then start over again.
What Fault Code are you getting?
If you get a code, we can work from there.
Give the set a good tune up - even though everything may look new, you still have no idea.
Change the oil, oil filter, air filter and spark plugs.
Onan had a lot of problems with the fuel pumps on these sets, and the carbs on these sets are very, very sensitive. Any sitting at all can lead to varnish build up.
It is not at all uncommon for a spark plug (even a brand new one), to act in this manner.
If you want to try the easiest things first, get a can of Sea Foam gas treatment from your local auto parts store.
Pour about 3 or 4 ounces into a gallon can of gas.
Remove the fuel line from the pump (not from the carburetor) on your genset, and install a piece of gas line 4 or 5 feet long. Place the other end of the line into the gas can.
Start the set and let it run for about 5 minutes.
Shut it down and let it sit overnight.
Run it the next day for about 5 minutes.
Do this for 3-4 days and see how it goes.

[Senior Chief]

The classic DIY method to clean your gennie carb without removing it is to get a can of Seafoam and add it to a gallon container of gas.

Disconnect the rubber gas line and run it into the 1 gal can- run the engine and burn the entire gallon. (should take about 1 to 1 1/2 hours) The "surging" so common with gennie engines is caused by the varnish built up from evaporated gas in the carb.

As a maintenance matter, you'll want to run your generator at least once a month for at least half an hour at at least 50% load (turn on one air conditioner or electric heater). Start the gennie without a load, let it warm up for a few minutes first. Shut the load down a few minutes before shutting off the gen.

This will keep both the gasoline motor portion and the generator itself in good working order.

[dennis1492]

Update
Well I had the mech. come over on this gen. he took off carb. which prev. owner told me it was 1 1/2 years old, he cleaned it one jet was dirty. Installed it back on, pumped out some dirty gas in line started it didn't seem to run much better, finally he took off the cap that you adjust the altitude adjustment and adjusted it runs great now. Apartently with the knob on the adjustment would not let it adjust right, Thanks to all your help/ input Soon on to my next problems LOL
Dennis