# Honda GCV190 w/auto throttle



## York_v45 (Jun 17, 2020)

This is a Simpson 3100 PW with a Honda GCV190 with auto throttle. The PW is a few years old and has surged and stalled at idle since purchased new. It starts and runs fine at full throttle as long as the wand is held open I should have taken it straight back to the box store but I had a job to get done. When I release the wand the engine will try to idle back but the result is wild surging that usually results in the engine stalling.

How do I adjust the auto throttle? I'm not finding much information online about it. Some posts refer to the pilot jet as a source of surging but that is with no reference to the auto throttle. Thanks in advance for all suggestions.


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## tabora (Sep 6, 2018)

Surging is not usually a throttle issue. Start by draining the carburetor bowl and letting some fresh fuel flow through it. Surging usually indicates a lean condition and water/contaminants in the bowl will also cause that to occur. If that simple step doesn't cure it, try cracking open the fuel cap and see if the surging stops. The vent may be partially clogged and fuel isn't flowing properly until the engine throttles up. If the problem still exists, it's probably time for a proper carb cleaning including the jets.


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## York_v45 (Jun 17, 2020)

Thanks for the suggestions.
It has done this since day one. I did take the carb apart when it was brand new, found no issues and the problem remained after reassembly. I will give it one more shot and the next step will be a new carb.
I've always assumed the problem was with the auto throttle because if you throttle it by hand it runs perfectly.


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## tabora (Sep 6, 2018)

I suppose it's possible that the idle screw is just set too low. What RPM range is it surging in? What is the actual full Simpson model number? Is it the MSV3024-I or something else?


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## York_v45 (Jun 17, 2020)

When surging it oscillates between idle and full RPM (3200?) at approximately a 2 second period. I got it up on the bench tonite and started some basic maintenance that was overdue. Oil change, plug, air filter. The auto throttle seems pretty simple. It's just a vacuum diaphragm attached to manifold vacuum, high vacuum pulls the throttle back to idle. Low vacuum allows the throttle to open. This works as part of the governor linkage, there is no adjustment for the auto throttle.
The float bowl was clean as a whistle, like new inside.


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## York_v45 (Jun 17, 2020)

I will get the model number


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## York_v45 (Jun 17, 2020)

I got it back together tonite and did accomplish some improvement. It starts and runs strong now and will cycle without stalling. What it's doing is cycling against the unloader. 
When the spray gun closes the load comes off and the auto throttle pulls it back to idle, as it approaches idle the pump unloader cycles and that throws the throttle open again. This repeats continuously. Before it would normally die but now it will continue to cycle. Is this normal operation? Is there something wrong with the unloader?


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## Melson (Dec 8, 2019)

Maybe your unloader has a leak and is always bypassing a small amount?

I say that based upon the way my washer's unloader holds pressure even after the engine stops. To me this normal operation.
But I only have experience with one washer so I don't know.
However, it also doesn't seem reasonable that a manufacturer would sell a unit that constantly cycles.


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## York_v45 (Jun 17, 2020)

I believe that most of my engine issues were caused by a loose main jet making it rich. It always ran better with no air filter. Now it runs good with the air filter in place.
My next step is to check the unloader for smooth operation. I've never had one of these apart before, I assume the unloader comes out without major surgery on the pump?


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## York_v45 (Jun 17, 2020)

I washed the entire house today to prep for painting. Ran 2 full tanks of fuel through it and it never stalled once. The surge at idle is gone and this is the best it's ever run. The biggest issue was the loose main jet. The surging I had the other day after working on the carb never happened today, it ran perfectly.
I never touched the unloader.


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## Melson (Dec 8, 2019)

Awesome. Good repair work. And thanks posting back the full outcome.


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