[bluegoose]

Good afternoon folks....

So I have been having some issues with my Pro-8 running smoothly, and then about 6-8 weeks ago, the machine finally croaks while working it. Suspecting the fuel pump, and then removing the line and visually confirming that no gas is spurting upward, I order a new one, and replace the old one. Bingo--it's up and running again! But not so fast :tango_face_sad: - a couple of days later, I go to start it again, and the same thing happens - machine "wants to start and run," and will run on starting fluid, but not on its own. So today I finally pull the carb (thinking that's the problem), and although the bowl has some residue in it, it looks good. Just for grins, I crank the engine again, and nothing is coming out of the (new) fuel pump deliver side - again :tango_face_sad:. Gas is flowing from the fuel line to the intake side of the pump - and I was able to siphon gas out of the delivery side of the pump as well. But the darn pump will not push the gas through on its own. Any thoughts as to whether I have another faulty pump (it is a aftermarket purchase), or whether I have an insufficient amount of gas flowing for the pump to prime and do its thing - or whether I have something totally different going on?

Thanks for the help!

 

[GravelyNM]

Is the plunger mechanism traveling enough to activate the pump?

Sent from my XT1575 using Tapatalk

 

[bluegoose]

Is the plunger mechanism traveling enough to activate the pump?

Sent from my XT1575 using Tapatalk

You got me on that one. Not sure how to check for that functioning. The activating arm that drives the pump is fully inserted into the engine cavity - beyond that I am not sure what testing to perform.

 

[Bigskyguy]

How does the fuel line look? Its possible its too soft and the pump is sucking the line shut. Also check the vent on the gas cap.

 

[nhgravely]

I believe these pumps are made by Airtex (spelling) and if so, they are the same general design as the pumps used on the military designed engines (1A08, 2A016, 4A032). Had the same issue, no pumping but could blow through the pump and fill the carb. Took one of these apart and the check valves are part of the diaphragm and get stiff from the ethanol gas we are stuck with these days. Soaked it in WD-40 and reinstalled. Worked OK. Suggest adding a little Marvel Mystery oil to the gas or as a friend does, add a little 2 cycle oil (like 75:1 or so). Seems to help with the ethanol problem and makes the gas more stable over time.

This ethanol gas (even @ 10%) is a real problem with our older engines. Have switched out to Cam2 race gas in all the 2 strokes I own but @ $9 a gallon it is a little too much for the bigger 4 cycle engines. And it is real stable for a much longer time in the can or in the tank. In my road bike for the winter just for that reason.

 

[ultane]

This ethanol gas (even @ 10%) is a real problem with our older engines. Have switched out to Cam2 race gas in all the 2 strokes I own but @ $9 a gallon it is a little too much for the bigger 4 cycle engines. And it is real stable for a much longer time in the can or in the tank. In my road bike for the winter just for that reason.

https://www.pure-gas.org/

There is also an iPhone app for pure-gas.org

 

[nhgravely]

Thanks, I knew of the pure-gas site and in fact buy my Cam2 gas at the listed Hudson, NH station.
The problem with most of the listed venders/locations is that they are carrying the small containers of non-ethanol gas mostly for lawn mowers and 2 cycle engines. If you want to buy in quantity you have to find the airports and marinas that carry the pure-gas in bulk. They are tougher to find, at least in our area.

 

[ultane]

I’m not sure what cam2 gas is. Does it have lead in it for the valves or seats?

Actually, EVERY gas station that I’ve been to (that’s on the pure-gas app) in Idaho, Oregon, Nevada, Wyoming, Colorado, Nebraska, Kansas, Iowa, Missouri, Arkansas, Tennessee, Mississippi, George, South Carolina, North Carolina, Virginia, and Florida were free standing gas stations that had a separate pump for ethanol free gasoline, along with the normal E-10 gasoline from their regular pumps. The 100% gasoline ranges from 87-93 octane depending on the source that the gas station uses for their fuel.

 

[tracktortag]

FWIW I had similar symptons with one of my fuel pumps. When I took it apart I found that one of the check valves had dislodged from it's seat in the plastic fuel pump housing. I cleaned up the seat area, an reset the valve in it's recess using a little MarineTex epoxy (impervious to gas). It's still working well.

This may not be your problem, but could be worth checking.

 

[bluegoose]

How does the fuel line look? Its possible its too soft and the pump is sucking the line shut. Also check the vent on the gas cap.

This K181 design was the last one...that has the fuel line behind the motor and out to the opposite side, where the carb and fuel pump are located. It's not the best design, if for no other reason than the fuel is prone to get warmer than it should. Portions of this line may still be original to the machine--which is a late 80's model Professional 8. It's just a strange situation, in that I can manually siphon the gas out from the ejection side of the aftermarket fuel pump, but when keyed to start, the fuel pump will not propel the fuel outward. Starting to wonder if there was anything wrong with the original pump at all...:tango_face_plain:

 

[Ietrucks]

Hello,
So the fuel itself may be the issue, according to the responses here? I have a Pro12, and after a few minutes, it too starts to shut off for no apparent reason. Going to try the marvel mystery oil.... Good luck with your Pro 8!!

 

[edwardgoodridge]

Run a gas line directly from the tank valve to the carb and check it that way. Use only gas rated rubber line and make connections secure before attempting a start. My experience with a Pro 10 is that gravity feed is sufficient most of the time for running these tractors. I never bothered to replace the pump on mine when it failed. The safety interlock switches on this series like the handle bar operator presence switches are known to fail and may cause a stall. I jumpered the handle bar switches on my Pro 10 as they were giving me huge back fires when they cut in and out. A replacement kit was offered for those it probably is still available as a NOS item.