# Kohler 20Resa Starting Problem



## DPavs (Dec 29, 2017)

I have a Kohler NG 20Resa that fails to start during the auto start cycle. This pretty much started to happen when the temperatures dipped below 45 degrees. During the cranks cycle the throttle positioner goes from closed to fully open as I believe it should but the unit will not start. There is a fairly heavy smell of the NG. If I hold the throttle at about half open or a bit less it will fire up and run fine afterwards. My guess is that there is something going on with the fuel mix but a new regulator was just installed about 6 months ago. Firmware was also updated at that time. The regulator and firmware work was done to fix a seeking issue with the throttle. 

Observations and things tried-
Choke plates seem to be opening and closing correctly. 
Carb heater is installed and working properly.
I tried heating the regulator with a hair dryer but it did not change anything. (saw this in another thread)
Plugs have been changed.
Oil is 5-30w synth and appears to be fine.
New battery was installed.

Any help or suggestions as to what could be going on would be greatly appreciated.


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## KRE (Nov 29, 2011)

From your description it sounds like your gas pressures are not correct. Regulators nor mixers come adjusted, they have to be adjusted to your system after installing. That unit has heaters for the Battery, gas reg an mixer(crab) if you opted for those for where you live are they working as designed? 
The speed control should go to full fuel upon startup, normally if you have to over ride it so the engine will start, you either have a vacuum issue, or a fuel pressure issue.


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## DPavs (Dec 29, 2017)

Makes sense that it is fuel related. I am told that the regulator for the Kohler 20RESA is not adjustable so if it is not putting out the right pressure it will need replaced again. As I have to throttle back to get the generator to start, would you suspect that the fuel pressure being delivered to the throttle body is actually too high?


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## KRE (Nov 29, 2011)

Depending the reg it may or may not be adjustable on such a small unit. When your closing the throttle your probably increasing the vacuum signal. I would have to see a drawing of your unit to be sure. Some regulators are designed to not allow fuel unless a vacuum is present, an if the supply pressure to the demand reg is higher than it should be it will take a stronger vacuum single to operate the reg. With the throttle plate wide open depending the vac port design, there may be very little vacuum to open the demand reg. This would be why it starts when you close the throttle somewhat. It then has a stronger vac signal to the demand reg an then fuel flows as it should. With the engine running even with the throttle wide open you would have a much stronger signal that if the unit was just cranking over an not running. Many guys will jack up the supply pressure to try to over come a pipe run that is to small for the distance. When everything is new sometimes this issue is undetected, unless the unit is full load tested. As units age an many things were installed wrong, or never adjusted properly everything stacks up, an now the unit will not preform.
HTH,
Kenneth


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## DPavs (Dec 29, 2017)

I think I understand. A question though. If insufficient fuel was the issue when it is at full throttle during the crank cycle... would I be smelling a lot of gas like I do? If anything it seems like it's getting too much gas because of the strong smell.


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## KRE (Nov 29, 2011)

DPavs said:


> I think I understand. A question though. If insufficient fuel was the issue when it is at full throttle during the crank cycle... would I be smelling a lot of gas like I do? If anything it seems like it's getting too much gas because of the strong smell.


Missed that sorry.
Are you sure the fuel smell is from the exhaust only? When you engage the starter the DC voltage operated fuel control valve opens an passes fuel to the system inside of the enclosure. If the fuel smell is coming from the exhaust only, then I would suspect either high fuel pressure at the mixer (carburetor), or very weak spark while cranking.


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## DPavs (Dec 29, 2017)

KRE said:


> Missed that sorry.
> Are you sure the fuel smell is from the exhaust only? When you engage the starter the DC voltage operated fuel control valve opens an passes fuel to the system inside of the enclosure. If the fuel smell is coming from the exhaust only, then I would suspect either high fuel pressure at the mixer (carburetor), or very weak spark while cranking.



Thanks this is pretty much the conclusion I am coming to also. So it would be either replace the regulator again or perhaps try replacing the coil pack. Do you think the coil output could be affected by lower temperatures and thus causing a weak spark or would you suspect something else?


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## KRE (Nov 29, 2011)

I doubt the coil pack is suffering from the temp change, but if the battery is not 100%, that will drop the voltage to the pack an spark plugs quick. 

I would not replace anything until I was sure that component was the problem. You should be able to find a service manual somewhere.


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## DPavs (Dec 29, 2017)

Battery is brand new and unfortunately the Service Manual only pointed back to things which have already been tried which is why I was hoping someone had run across this same thing before and found some magic fix!


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## DPavs (Dec 29, 2017)

Just an update and resolution. It was the new fuel regulator which was installed several months ago. It was defective right out of the box apparently or mis-configured from the factory. During warm weather it was not apparent it was not allowing adequate pressure through but in the cold weather it was not providing enough fuel to start the generator.


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## Handyhiker (Sep 29, 2016)

Thanks for the update!!


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## mxsmith4 (Dec 22, 2019)

Thanks posting the solution. I had a similar problem with my 20RESA when the temperature went below freezing this year. The unit was installed and manufactured in 2012 and recently started to fail the weekly exercise with an overcrank failure. I checked the battery and purchased a manometer to check the fuel pressure at the fuel switch in the generator, pressure was 10 inches. The unit would start if I manually pulled back the throttle and would continue to run but it would not start on its own.

I replaced the fuel regulator and the unit now starts on it's own. For others that want to replace their regulator the new regulator that I purchased had a different size plug for the test port. I believe the original regulator had an 1/8" plug, the new regulator had a 1/4" plug so check that out before you start the job. I was unable to remove the gas supply hose to the carb from the regulator outlet so I just unscrewed the outlet with the hose attached without cracking the hose, the hose was loose enough to let the outlet spin I just didn't want to risk cracking the hose as I did not have a replacement handy. So keep that in mind too, you may need to replace the rubber hose.


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