Skid steer fuel

I have an old Mustang skid steer. Every thing works good except the fuel pump. It has one of those ones you see on riding lawnmowers. It is connected to the crankcase with 1/4" hose. Could someone explain how to troubleshoot that. I have to crank forever before it starts, then everything is fine. Once it warms up it starts right away.

(quoted from post at 08:47:58 11/09/19) I have an old Mustang skid steer. Every thing works good except the fuel pump. It has one of those ones you see on riding lawnmowers. It is connected to the crankcase with 1/4" hose. Could someone explain how to troubleshoot that. I have to crank forever before it starts, then everything is fine. Once it warms up it starts right away.

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Replace it with a low pressure electric fuel pump.

if i understand correctly..

you have the pump that uses the pulsing air pressure from the crank case to move a diaphragm back and forth to pump gas.

The diaphragm can get hard and not work well, or the fuel hose can get a crack and not pump well.

These pumps are pretty cheap to replace as they are on lawn mower engines..

remove the output hose and crank.. you should see pulsing gas coming out of the pump if working correctly.

Disconnect the hose from the pump to the carb crank the engine watch to see if fuel pumps out it if it does the fuel is ok if its not good the sell on e bay Amazon etc for $10 to $25.00

I thought about that, but I've seen
alot of burnt up skid steers at the
salvage yard.

is your choke working correctly,seen that be issue but blame fuel pump,take line off at carb and have someone turn it over see if you get full fuel flow into a container

The engine crankcase is sealed not vented on these type of engines. So as the pistons cycle they create a air pulse. The fuel pump has a diaphragm that contracts and expands with the pulses. This action when combines with check valves pumps the fuel.

So you can easily have a bad pump. You can check them by removing them form the fuel circuit and then putting a short hose on the air port. The using you mouth suck on the line creating a vacuum. Do this in a rhythmic manner and you should be able to feel vacuum on the inlet side of the fuel pump. Usually when they are bad you will be able to suck air straight through the pump.

On the motor side just hold your finger over the pulse line and crank the motor over. You should be able to feel the air pulsing in and out. If not than you have a crankcase leak.

P.S. I had a fellow that would complain his new mower would not start or run correctly. I went out and he had failed to tighten the oil dip stick. So the mower would run a few seconds on the fuel in the carb. and then die. He did this multiple times. He even called JDs service hot line complaining about our service department doing nothing. Got us a visit by the territory service manager. I had to show him how it would do that on a new mower that we had on the show room floor. Old fellow was so forgetful he could not remember how to do things but blamed everyone else for his troubles.

Bob why not just fix the original pump system???? The pulse pumps are much simpler and cheaper to maintain. They also will not pump your crankcase full of fuel if they fail to shut off or start to pump higher pressure. I have seen two different motors ruined with gas in the engine oil, caused by a malfunctioning after market fuel pump.

I agree with JD

I would be more suspicious of a choke or carb problem.

Unless it's been stored a long time since it was last started, or it was run out of fuel, there should be enough fuel in the carb bowl to get it started.

Be sure the choke is fully closing.

If there is a fuel solenoid on the bottom of the carb, be sure it is getting power while cranking.

Look for fuel leakage around the carb bowl. Could be the center gasket leaking or the bowl has a rust pin hole.

Thanks for all the replies. The oil dipstick has a tighten T handle and rubber stopper on it. That could be leaking. That little pump has a big job to do because the gas tank is on the bottom of the skid steer and the carburetor is 4 foot up on the top of the engine.

With a system like that, shouldn't there be a foot valve in the end of the tank pickup, to keep the line full? Perhaps it is stuck open, allowing gravity to siphon the fuel back to the tank when shut down.

You didn't say what brand the engine is in your Mustang skid steer, maybe an ONAN by chance? I have an Onan B48G in my 982 Cub Cadet. It was completely rebuilt by somebody that supposedly had done hundreds of rebuilds on them. I'm less than impressed. The rubber hose from the crankcase to fuel pump fell off, but it still ran, just was much harder to start. Even with that hose attached and clamped, and with a new pump costing over $100 it still starts hard. An electric fuel pump would get fuel to the empty float bowl quicker. If you shut it off hot you smell gas vapors immediately. I joined Weekend Freedom Machines website just to see what was wrong with the governor on this Onan. They press a nylon finger wheel onto a machined hub on the camshaft gear. Nylon, and ALL plastics grow when hot, the finger wheel slips and doesn't spin the steel ball bearings out against the spring loaded conical washer which opens/closes the throttle in the carb. Mowing into grass that gets taller the engine would pull down, but shove the throttle wide open and it would speed up instantly but would over speed when the load was reduced. Onan makes a finger wheel now I guess with a longer finger that engages a notch cast into the gear. Had the Onan stop on me once when mowing. Pulled the cover off the points. They looked like they had been dipped in 90W gear oil, covered in oil from hot oil vapor inside the crankcase. Cleaned the points and it started instantly. Tractor has been totally reliable, but I stopped using it because every time I ran it I felt the D-Day clock was ticking down to a catastrophic engine failure. OH, new points & condensers only lasted 50-60 hours and cost $100 from Onan.

I only use it a few times a year to clean the paddock. Because of all the rain, I used it once this year. Carburetor and choke work good. So yes it sits most of the time.

(quoted from post at 09:06:40 11/09/19) Bob why not just fix the original pump system???? The pulse pumps are much simpler and cheaper to maintain. They also will not pump your crankcase full of fuel if they fail to shut off or start to pump higher pressure. I have seen two different motors ruined with gas in the engine oil, caused by a malfunctioning after market fuel pump.

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I typically install electric fuel pumps with an oil pressure switch and a priming button.

Makes it much easier on the starter, and no danger of pumping gas if the engine stalls.

A lot of aftermarket fuel pumps come with instructions on how to connect that all up, for those who don't know.

I have (thankfully) never witnessed or heard of before, of a correct-for-small-engines low pressure fuel pump somehow reverting to pumping at a higher pressure. (NOT talking about any more modern/high-tech stuff here than a basic electric pulse fuel pump.)

I believe the pressure made by a "pulse-type" electric fuel pump is determined by the strength of an internal spring.

An electromagnet pulls back a plunger against a spring, then releases, the strength of the spring pushes the plunger, pumping the fuel, and it's strength determines maximum fuel pressure.