I think the pain thinner destroyed the walbro pump.
 Not sure yet. Thinner is squirting out the relief hole
 on the top of the pump.
   Paul Lamar

Your friend is quite a joker.  He's probably laughing his head off.
"This will fix Paul!"

Mark Waldron

Probably but can anybody tell me what is wrong? Hint.. take a look
at the plumbing picture I up loaded.


Paul Lamar

The valve on top of Walbro GSS 341s ("255lph high pressure") can be a
bit unreliable. Enough so that I'd be wary of using one for an
aircraft without disabling the valve somehow.

When I was trying to troubleshoot fuel starvation issues under boost
on a friend's car, we discovered this valve had failed. After plugging
it with epoxy, there haven't been any problems.

-Chris Wood

I agree with that. I am not happy with the one I have as the valve is
popping off
all the time as I have only one injector on it right at the moment and
the injector is off most of the time. The other thing I don't like about it
is the plastic
hose barb. Vinyl hose slips right off at over 60 psi no matter how tight the
hose clamp.
I had to change the hose to rubber to keep it on. That is scary for aircraft
use. I have two Walbro type pumps and both have plastic barbs.

The pulse width modulated high pressure
pump is long over due but I am setting that project aside for another time.
In the mean time I am turning down the pump voltage just enough to maintain
fuel pressure. The other thing I have learned is that Aeromotive regulators
are
leaking vacuum so bad I am unable to pump it down to less than 15 inches of
Hg.
I have not put a condom on it yet as per Larry suggestion. I sure wish
I had one that does not leak.

I bought a better used pump from Klaus that Air Flow Research sells. It has
metal hose barbs and is much more robust. It looks a lot like an MSD
pump. It could in fact be an MSD pump. Tracy used to sell a pump but I don't
see
it on his web site now.

The Ford Explorer looks pretty good with a metal hose barb.

BTW the paint thinner seems to have somewhat higher viscosity than
gasoline so I am not sure what affect that has on the pumps.
The RX8 injector deals with it well at 55 psi so far with a very fine
mist.

Paul Lamar


Walbro makes an inline version of that pump with hose barbs on either
end, but it is more expensive and less commonly available if I recall.

Vacuum leaking seems to just happen on those regulators. I have tried
teflon tape and grease with some success, but both are less than
ideal. In my application the leak was small enough that the regulator
pressure/vacuum stayed virtually the same as manifold pressure.

Ford uses returnless systems with pulsewidth modulation on recent EFI.
It might be closely calibrated to specific fuel pumps because a friend
who deals directly with those systems says they become unreliable with
changes of the pump.

-Chris Wood

Thanks Chris. Interesting info on the PWM pumps.

I'll try to talk Larry into making some pressure regulators that don't
leak :) An interference fit long nylon nut might be the answer.

Larry, can you make an interference fit nylon nut? Will it
require a custom tap? Lets apply for a patent :)


Paul Lamar