usnavyvet

Hello,

I've got a Swisher tow-behind finish mower with a stalling problem. It will run great when it runs, but will periodically just stall out. Sometimes it will not restart immediately.

When the engine begins to stutter, it can be kept running with starter fluid, also a timing light verifies that spark is occuring even when it won't fire.
Plug, filter, and gas are new. Gas appears plentiful at the carb input. The mower was taken to a small engine repair shop, but they were not successful in repairing it.

I believe, at this point,that it is either dirt or a float problem in the carb, but I have a couple of questions:

The suspect carb is a NIKKI, but I can get a WALBRO replacement. It appears to be a direct substitute, but should I do this or attempt to rebuild the NIKKI carb? The price of a replacement isn't much more than the rebuild kit.

Can someone explain the function of the fuel solenoid that both carbs have?
Without a wiring diagram, I am unsure if this is a switch that turns off the ignition when the bowl empties, or if it is a relay that permits fuel flow into the bowl, or ????.

Thanks in advance

John

usnavyvet

Ok, guys, I need some help here...... I have, from another site, begun to comprehend the function of the fuel solenoid, that is, to prevent flooding when the mower is not being used, but, I want to understand just how the fuel solenoid works in the float bowl. I don't quite understand why the solenoid is necessary. Wouldn't the float stop fuel flow once the bowl was full? If so, why is a solenoid necessary to prevent flow when the ignition is off? Safety backup?
And how does it accomplish this? Does a spring restrict the float from moving when the ignition is off and the solenoid pulls the spring out of the way?....... OR....... ?????

I read in that same other forum that a bolt of the correct size and length can be substituted for the solenoid for testing. I dont understand how this would work.

Anybody know??

Basementgeek

Hi and welcome to the forum

Can you give us the complete model number off the engine? That will help us.

BG

usnavyvet

I will, but I have resolved the issue, it is a problem with the fuel solenoid. The solenoid is evidently dropping out and stopping the bowl from filling. I determined this by removing the rubber seal off of the end of the solenoid plunger (so the plunger was not long enough to interfere with the float action even when deenergized) With this test setup, I was able to run the engine successfully. I've ordered a new solenoid.

B/s model: 280H07 type: 0117E1

Also answered my question regarding the solenoid action relating to the float. How it is supposed to work is: with the ignition on the solenoid is energized, and permits the float to follow the fuel level in the bowl. When the ignition is off, the plunger on the solenoid is pushed by the spring to contact the float and prevents it from opening the bowl input from the fuel source.

k2skier

Very close. It's called an after fire solenoid, it stops the fuel flow when the engine is shut off so fuel isn't pumped into the hot muffler, and BANG, the after fire.

It actually plugs up the main jet/nozzle to stop the fuel flow.

usnavyvet

Thanks for the clarification. I suspect it isn't very essential on a gravity feed fuel system,(at least my mower is not backfiring with the solenoid function disabled). But I believe the carb is used on a multitude of S/W engines, some with and without a fuel pump. If a pump was involved, I can see how the pressure might cause gas to seep past the carb.

In any event, it mowed 5+ acres without stalling, with the solenoid function disabled. I'm awaiting delivery of a new solenoid, and my expectations that the problem is resolved is high.

Basementgeek

The after fire solenoid is to keep the engine from "back fire" when you kill the spark with engine running to fast. Always idle an engine down before shutting it off and you should have no problem with out it. Older engine's did not have them.

BG

usnavyvet

I think i prefer to replace it. With most all tools, I've found if you defer maintenance, the equipment starts a downhill slide that shortens it's useful life. This mower (Swisher tow behind) is in its fifth season, and I don't think it's at half-life yet. It hasn't had an easy life, but I do keep the essentials in good repair as possible.