Hi, all,
I have asked this before, and didn't get an answer that
pointed me to a source. Well, the thing popped again, so
I am in need again. I made a little fuel pump for my insane
yard tractor rebuild some years ago. I used some misc.
rubber material for the diaphragm, and it holds for about
2 years, then starts to leak. I bought some stuff specifically
sold for this purpose, with some cord sandwiched between Neoprene.
it is really too stiff for the little motor, and it only lasts
a couple months before is breaks up at the cors and starts leaking.
Grumble! So, does anyone know of a source for a good pump
diaphragm material that can take continuous exposure to auto
gasoline, and is still pretty flexible? I might have to buy
some cheap mechanical pump and take the diaphragm out of it,
or find a tiny commercial fuel pump that I can use.
I don't need a lot of head pressure, this needs to lift the gas
no more than one foot, and deliver maybe 2 GPM if it was on
all the time.
OK, here's the whole scoop (I ought to put pictures on my web
site.) It is a 1968-vintage Bolens tractor with a 12 Hp
Wisconsin engine. It had this hideous little updraft carb
that was poorly made to start with, and in worse condition,
with no parts available. I had a Honda motorcycle carb
laying around, and jury-rigged it, and it worked great.
But, it needed the gas delivered higher than for the updraft
carb. So, I put a little header tank above the carb, and
put a float switch in the header tank to turn on the pump
when the tank was low. This all works fine, except for the
pump diaphragm.
Thanks in advance if anyone can point me to a source of a
good diaphragm material.
Jon
Jon, you're making this far too difficult for yourself. Bypass the
mechanical fuel pump and go buy a simple universal electronic fuel pump from
an automobile parts store. Like these Purolator pumps from
formatting link
Purolator PRO04SV: Fuel Pump, Universal
Electronic; Solid State; POSI-FLO® Pump; 1.5-4 PSI; 25 GPH;
3 Month Limited Warranty
Ships in 1 day
$39.99
Purolator PRO06SV: Fuel Pump, Universal
Electronic; Solid State; POSI-FLO® Pump; 4-7 PSI; 32 GPH;
3 Month Limited Warranty
Ships in 1 day
$39.99
With one of these, you can probably scrap your makeshift header tank too.
Regards,
Michael
Jon,
You could go find a junker tractor someplace and take the vacuum
operated fuel pump off the side of the engine. They have an "in",
"out", and vacuum port which works of the stroke of the engine using
the crankcase vacuum. You wouldn't need the extra tank above the carb
and they last almost forever.
Ken
It's not cord-reinforced, but Santoprene sheeting will take the exposure to
the solvents. It's a modified polypropylene/butadiene rubber; immune to
most solvents. Not great on heat, though.
LLoyd
The vacuum fuel pump on my old 18HP Sears tractor was made to mount on
the firewall instead of the carburetor so one like it would be even
easier to adapt.
It didn't work when I was given the tractor (not much else did,
either), but it just needed the rust from wet coast-of-Maine gasoline
cleaned out.
jw
OK, do you know where to get some of this? It sounds like something to
try. I really don't know what the problem here is. As the existing
material lasts 2 years, I don't think it really is a solvent breakdown
problem, but a wear problem, or maybe a combination of the two.
Thanks again,
Jon
No, the motorcycle carb is designed for very low gravity fuel pressure,
and I don't think it likes any more than a few inches of head above it.
These things are $40 plus tax, and then I'd still have to add a check
valve (I think) and a switching circuit to turn it on and off. It
delivers way too much fuel, so I'd probably need an orifice to throttle
it back some. It does look like it would work after all these
adjustments were made, though. 25 gal/hr? Who could possibly need
that much fuel flow?
Jon
| Hi, all,
|
| I have asked this before, and didn't get an answer that
| pointed me to a source. Well, the thing popped again, so
| I am in need again. I made a little fuel pump for my insane
| yard tractor rebuild some years ago. I used some misc.
| rubber material for the diaphragm, and it holds for about
| 2 years, then starts to leak. I bought some stuff specifically
| sold for this purpose, with some cord sandwiched between Neoprene.
| it is really too stiff for the little motor, and it only lasts
| a couple months before is breaks up at the cors and starts leaking.
| Grumble! So, does anyone know of a source for a good pump
| diaphragm material that can take continuous exposure to auto
| gasoline, and is still pretty flexible? I might have to buy
| some cheap mechanical pump and take the diaphragm out of it,
| or find a tiny commercial fuel pump that I can use.
|
| I don't need a lot of head pressure, this needs to lift the gas
| no more than one foot, and deliver maybe 2 GPM if it was on
| all the time.
John I think that jet-skis and similar watercraft use a fuel pump that
has enough head for your application. IIRC, the exhaust gas pulses operate
the pump, but I may be wrong. Sound like what you need, though.
How about viton? Excellent resistance to oil and fuels and high
temperatures. See
formatting link
part 86075K31. It's a little stiff
at shore 75A but should work ok. Browse their catalog, you might find
something better. I know they have buna N as soft as 50A but I think
the viton would resist the fuel longer.
--
Regards,
Carl Ijames carl.ijames at verizon.net
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