Genny carb issue or fuel pump, advice needed

[Capt Kangeroo]

Hello all. I have a low hours Kohler 8E gas generator 1999 vintage which refuses to run unless I pour gas down the carb. It will continue to run as long as I keep pouring in gas. I have changed the gas filter feeding the carb but no luck. By my way of thinking it has to be the carb or fuel pump but which? Beating on the float bowl in the event of a stuck float did not help. The fuel pump is getting voltage. Does anyone have some suggestions for tests and checks I could do to isolate the problem.


Will any 12V fuel pump work or does it have to be sized to the carb and system. The one thats on it is a Carter.



All advice / suggestions welcomed.
Thanks! KC

 

[porman]

Pull the fuel line off the carb and stick it in a container. Try starting the generator and see if fuel comes out of the line. If it does then the fuel pump is working.

 

[O C Diver]

If you remove the fuel hose to the carburetor (disconnect the power to the fuel pump first) and replace it with a piece of 10' vinyl tubing of the same size you can determine whether the fuel pump is bad. If you fill the tubing with gasoline and elevate the open end of the hose, you can generate fuel pressure to the carburetor. For every foot you elevate the hose end above the carburetor, you will gain 1/2 PSI of pressure. So elevating it 8' will give you 4 PSI to the carburetor. I would expect 4 or 5 PSI of pressure should allow you to start the engine.

Alternatively, if you disconnect the fuel hose from the carburetor and put it in a container, you can see if fuel flows from the pump when you try to start the generator.

Ted

 

[Lepke]

Any 12v pump will work. You need to determine if fuel is reaching the carb. With the key on, you should feel the fuel pump vibrate until the fuel bowl if full. You could loosen the fitting at the carb, have someone turn on the key and look for fuel. With the pump off, if there is a fuel bowl drain, try to drain the fuel into a container or rag. Remember gas vapors can explode in confined spaces. You should have the bilge blower running.

It's common for gas engines to have fuel blocking build ups when sitting for months. All gas should have a stabilizer added if it is sitting for more than 6 months. Current fuels are no longer formulated for stability and burn, but unique clean burning.
My guess if the pump works, and fuel is reaching the carb, the carb needs to be rebuilt.
If no fuel is reaching the pump or carb, you could have build ups in the tank pick up, filter, or anywhere in the fuel line. You start at the tank and work towards the carb.

 

[kehoff]

so see if it has fuel and then you may need to clean the carb if you feel comfortable , here is a video , the only thing I am not sure of is if there are any safety switch for low water etc , also a cheap fuel pump will work for it ,make sure it is low presssure, try this

 

[Bmarler]

a gas engine made in 1999 may not have been engineered for fuel including ethanol. if you have been using e-10 there could be damage to the fuel pump diaphragm or other rubber parts inside the carb itself. many fuel docks just sell straight gas, but not all.
when you replace fuel system parts it's always a good idea to check to see the parts you're installing are good to use with e-10.

 

[DavidM]

Even brand new RV gas generators from Onan have carb problems due to ethanol gas getting water in it and fouling up the small passages. I have done this a half dozen times and it has always worked, but first check to see if it is getting fuel per above.

Remove the carb and disassemble at least as far as removing the float bowl. Then soak the parts overnight in a can of carb cleaner that you can buy at any auto parts store. Turn over the parts a couple of times while soaking.

Then remove the parts, blot with a paper towel to remove residual carb cleaner, reassemble and reinstall the carb. Nine times out of ten it will start.

Then make sure if you store for more than a month or two, use a fuel stabilizer like Stabil.

David

 

[Capt Kangeroo]

Thanks guys, much appreciate the great tips. Unfortunately I live in this frozen wasteland called Canada & will have to wait until spring to try out these ideas. I'm putting my money on a defective fuel pump and given how cheap they are I think I'll buy a new one and keep it as a spare in the event it turns out to be the carb.


Incidentally, I did power the pump with the hose off the pump outlet and it seemed like very little gas to me and little if any pressure at all.


I don't think it is an ethanol mix issue as the genny draws from the main tank but I can't say for sure I haven't accidentally filled the tank with ethanol from some of the backwater marinas.


Kehoff, I also wondered about safety switches but it seems to me if it will run by pouring in gas, they shouldn't be an issue. Thanks for the video by the way.



Re the pump, If I understand correctly, I should be looking for a 12V pump with a rating of 4psi and the same size inlet & outlet? Does it matter if the PSI is more or less? Is there any other spec I should be considering?



KC

 

[rslifkin]

If the rubber fuel lines on your boat are original, at this age, just replace them. Old lines can collapse internally and block flow (especially if they're not ethanol compatible and were exposed to ethanol gas). I've seen quite a few serious troubleshooting efforts go on for weeks before finding a collapsed fuel line as the problem. And personally, I don't trust even good fuel lines for more than 10, maybe 15 years.

 

[KnotYet]

AFAIK, unless the gas you buy is marked 'ethanol free', it has some ethanol in it.

 

[Comodave]

If the rubber fuel lines on your boat are original, at this age, just replace them. Old lines can collapse internally and block flow (especially if they're not ethanol compatible and were exposed to ethanol gas). I've seen quite a few serious troubleshooting efforts go on for weeks before finding a collapsed fuel line as the problem. And personally, I don't trust even good fuel lines for more than 10, maybe 15 years.

This is certainly something to check. Also there is likely an anti siphon valve in the fuel pickup that could be bad and stop fuel flow.

 

[Pete Meisinger]

Sediment bowl or filter is probably full of water.

pete

 

[Lepke]

Re the pump, If I understand correctly, I should be looking for a 12V pump with a rating of 4psi and the same size inlet & outlet? Does it matter if the PSI is more or less? Is there any other spec I should be considering?
KC

Any pump sold for gasoline as you describe will work. Any autoparts store, Amazon or ebay. About $12 and up.

 

[Mischief Managed]

The OEM electric fuel pump on your genset is quite simple and can be opened up and probably fixed. I'd bet the sliding metal vanes are just rusted in place. Clean up the rust to get them moving again and it will likely work fine. If that does not help, make sure the check valve at the top of the fuel tank is not frozen with rust.



Those gensets have a diode on the starter solenoid that can short out internally and fry the main circuit board since there is no fuse in the circuit. Add a 10 amp fuse to that diode.