Hustler Super Z and Kawasaki 23hp eng.

I posted a few weeks ago about a Hustler Super Z zero turn with a
Kawasaki 23 hp engine. The engine would miss after it ran for an hour or
so. The miss was in the rear cylinder of the horizontal opposed engine.
After replacing both coils it would not start. This mower has been to
the shop several times for poor running problems. We finally replaced
the fuel pump for the third time in the last year and now runs
perfectly. New fuel pump has BS stamped in it not Kawasaki. The one the
shop installed is stamped BS also. Not sure what the original one was.
Is there a better pump out there? Does Kawasaki make their own? Don't
want to keep going thru this.
To sum this up, we had two bad Fuel pumps and at least one bad coil in
the last 6 months. Makes trouble shooting difficult.

Dave.

Holding them in my hands, I can't tell the difference between the older Kawasaki fuel pump and the Briggs and Stratton part. The Kohler Command pump is identical as well. We keep the Kawasaki pump in stock for warranty work. But for most other repairs, the Briggs part is a lot cheaper than either Kawasaki or Kohler and works just as well.

Both Kohler and Kawasaki have gone to different fuel pumps in the last few years. The newer Kawasaki pump has the ports in a different location. The Kohler pump looks a lot like the fuel pump on Predator engines, So I assume its of Chinese origin.

Thanks. Do you ever have problems with those pumps? Do I have something causing them to go bad? These run off pressure from the cylinder head correct, do I maybe have a problem there?
Thanks for your reply.
Dave.

Those pumps usually last a long time. I am guessing its fate getting you bad pumps.

If it was me doing the job, to be sure I had covered all the bases, I would change all the fuel lines back to the tank. If the fuel line goes in the top of the tank, I would also pull the pickup tube from the tank and inspect it. I found one that had folded flat about 3" from the bottom end. I have also seen three mowers this year with trash in the tank that periodically blocked the pickup tube. By periodically, I mean it could run anywhere from 5 minutes or 30 minutes before they had problems.

We are, however, telling our customers to put either non-ethanol gas in their tanks or use 93 octane gasoline. The 'regular' (89 octane) you get around here in NC has all the alcohol the gov't allows in it. The alcohol attacks plastic parts elsewhere in the system, like o-rings in the carburetor, so presumably it could attack the diaphragm in the fuel pump as well.

You asked how those work: The way I understand it, the pressure in the crankcase goes up when the piston comes down the cylinder and down when the piston goes up the cylinder. So the pump uses the change in pressure to pull fuel through one check valve and force it through another. (I have only seen one of those that could develop 2 psi, however, so the pressure is not all that great. Most only do about 1-1/2 psi.) There is just enough pressure to move the fuel.

Thank you, I we will investigate those items.
Dave

The previous description of the operation is correct. They are referred to as pulse pumps after the crankcase pressure pulse. The crankcase actually will go from a vacuum to pressure as the pistons move up/down.

What is often overlooked is the dipstick seal. If it is loose or the seal is defective the pressure/vacuum pulse is weakened and will cause the pump to fail to deliver fuel.

I have thought about putting an electric pump on our Husqvarna with a Kawasaki, if it hasn't been used for awhile it has to crank a little. I would thing with an electric pump it would start a lot quicker, especially if it has been run out of gas. Anyone ever do that?

I use a squeeze bulb like on a boat engine. Sea Sense makes a good one.