Kohler Genset - Lift Pump

[scottscar54]

Hello all. Have searched and searched but nothing close to what I am experiencing.

Kohler 4CZ23 genset on a searay sundancer 270.

Genset would not start but suspected a fuel problem. Checked the fuel and turns out there is a lift pump (old skinner coil driven lift pump in the fuel line about 4 feet back from the genset). The lift pump did not seem to be working so tried a generic low pressure automotive fuel pump. Was only able to get it to start if I mess with the valves on the carburetor (have to hold it about half way until it warms up some then it idles mostly okay).

Can get generator running but it seems to starve for fuel (know because installed a valve in line I can close or open to test fuel flow which when closed even half way has no effect). The genset shuts off after a minute or so. When I apply a load like AC, it then shuts down almost immediately.

Have searched for a similar fuel lift pump with no luck. What I do know is that the original lift pump was rated at a maximum of 3psi but it did not say its pass through capacity. Furthermore, I assume the pump turns off when it reaches pressure and the genset takes care of it with the built in fuel pump.

Anyone have suggestions on a suitable lift pump replacement? I have found an electric fuel pump from Carter that is low pressure (6 psi max) that shuts off when it reaches pressure and has more than sufficient flow through of 72gph (way more than the genset should need) and is RATED FOR MARINE USE. Don't want to buy it to find out that it doesn't work for my needs.

Main concern is that the max psi of the carter pump when running is too much and will cause the genset to run rich causing the genset to shut down without messing with the carburetor. Tried to find original manuals for genset in order to hopefully find its fuel consumption requirements but can't find it at all.

Any help is greatly appreciated!!!

 

[ehenry]

Re: Kohler Genset - Lift Pump

The symptoms you're describing indicate that the carburetor may have an issue if you put another pump on the genset and fuel is getting to the carburetor. I dont understand what you're saying when you say "Was only able to get it to start if I mess with the valves on the carburetor". Do you mean the choke ? If this is the case I'd say the carburetor need a rebuild that the main jet is partially stopped up.

 

[scottscar54]

Re: Kohler Genset - Lift Pump

Thanks for your response.

Yes. I guess that would be the choke after finding the manual yesterday (sorry not so familiar with the maintenance of the genset).

The reason I am suspicious of the lift pump is that the orignial lift pump died. There was NO FUEL from it at all (tested the fuel delivery of that original lift pump and found no output at all). I found a low pressure pump that I thought would work but it is an automotive pump that I put in temporarily. Not sure that it self regulates or allows for flow through that is why I ask. It does provide fuel but not sure in the right quantity. I am still suspicious of the aftermarket pump I bought and was hoping someone might have a suggestion for a suitable low pressure lift pump specifically approved for marine use for this application.

The other thing I noticed was that when I put a load on the genset when it was running, the genset seemed to starve for fuel and then die out (shut off). Power down the AC unit, restart genset, and it runs fine, until I try running the AC again. The original manual I have for it indicates this in its troubleshooting section as a possible lean condition. That adds to my suspicions of the lift pump replacement.

Guess I could work on rebuilding carb on top of fixing up the fuel delivery problem. Is it at all like the old automotive carbs? If so, I am more than confident in my skills as have rebuilt literally dozens for cars.

Thanks for your help.

 

[kg5388]

Re: Kohler Genset - Lift Pump

all parts used in a boat must be marine approved parts they may be/ look the same but the part numbers must match those for marine use.

use a pump from napa for automotive use and something happens insurance will not pay

put a gauge at the carb and see if fuel pressure drops when you hit it with the load

sounds like a carb problem and you need to rebuild/replace or since it runs mix some fuel heavy with seafoam and run it for awhile and see if it helps

 

[scottscar54]

Re: Kohler Genset - Lift Pump

Thanks again for the help. Found an electric fuel pump from a online boat parts dealer and have installed that.

Went back to an old trick my dad taught me decades ago on every boat we owned - Marvel Mystery Oil in the fuel tank.

Also cleaned the carb with carb cleaner.

Still ran rough at first but after a few minutes, finally went back to running like it used to.

Sure the fuel lift pump was faulty but may also have been gummed carb so took care of both just in case.

Thanks.