Chraftsman 18hp. twin fuel problem

[Rick]

We have an 18 hp. twin fuel pump on the side of the carb . It was working fine and then quit . It appeared that it was lack of gas as it would start and run as long as you pored the gas in the carb . I rebuilt the fuel pump and it still wasn't getting fuel . I took the top off the carb and it was bone dry . I replaced the needle valve and it still didn't get fuel . This time when the carb was apart I pored some gas in the bowl and pored gas to the fuel pump line doing it several times and turning it over to prime the pump . When I put the carb back together it started right up and ran good . I took it out to try mowing with it an again after about 10 minutes it acted like it was starving for gas . Then it stalled again . Same problem . The fuel pump seems to be powered by a vacum hose coming up from the crankcase . Is there anything in the crankcase (filter)or something that would plug up ? I can feel som air coming out of the hose when I turn it over . I can suck fuel out of the gas line at the fuel pump connection from the tank...Any ideas...Rick

[Srgnt Billko]

I don't screw around - I go to NAPA and get a low pressure electric fuel pump and install that. I haven't had to remove the old diaghram pumps yet - but when the tanks are low and in the rear I mount the electric pump back there. The one I installed a couple weeks ago I ran from the light switch that was no longer used so I can shut it on and off. Others I have right from the ignition switch.

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[Art]

That pump works off of alternating pressure and vacuum from the crankcase. They do not develop much pressure at all. I've never seen a pulse line get plugged. When you rebuilt the fuel pump did you clean every speck of the old gaskets off? I usually run a flat file over the pump body and cover lightly several times to make sure it is clean and flat. The thin rubber diaphragm goes against the body, then the gasket, then the cover. Check the pickup in the bottom of the tank, many have screens, and clean as needed. If there is an in-line fuel filter replace it with one from a small engine shop. Do not use an automotive or paper type fuel filter. That pump will not develop enough pressure to get the fuel through it. Also check the fuel line. If it is cracking at the ends or is soft and squishy, replace it. Also check that the fuel cap is vented.

You are on the right track. Good luck.

[Art]

I've never done that. Have you ever had any problems with the carb flooding? My concern is that even a low pressure electric pump might overcome the pressure on the needle from the float.

[Rick]

Thanks for responding , I'm curious , how many LB. pressure pump do you use . I kind of would like to figure out the problem . It has worked flawlessly this way for 25 years . Rick

[Rick]

Thaks for the info, The filter came from Laser Sales (a small engine supply ) It is clear plastic and the filter media inside looks like a GM filter (the small ones that go in the carb . I can suck gas through the line right from the connection at the fuel pump . I light sanded the surfaces to make sure I had everything . I wasn't aware there was a pickup screen in the tank . I will check on it . I certainly acts like the fuel is being restricted . Rick

[Srgnt Billko]

No - and my nephew uses the same approach. He buys and sells - I just collect.

[Srgnt Billko]

I just put one on a 18 HP Briggs twin on a 1984 Agway (Murray). I have one on a 1960's 70's Sears Suburban 16 HP single (Tecumseh). And I put one on a

1980's Sears twin that I sold. As I said above, my nephew also uses them.

[Srgnt Billko]

All good advice - especially the file rather than sand paper.

[ds549]

replaceing all the fuel line and pulse line could help too.