On Mon, 06 Aug 2007 11:48:07 +1000, "K. Smith" wrote:

wrote:
Thanks, the oil line was plugged properly. I even changed that line
and put in a new plug. Today I tested it all out....
New lines, new diaphragms, new bulb/hose assembly. Same problem. Just
can't suck gas at anything other than at idle.
At first I had the vacuum line and gas supply lines swapped by
mistake and I noticed gas leaking from the larger diaphragm side. This
leads me to believe there must be an air leak in the fuel pump housing
itself. Both tanks have the same issue, and are clean and not very
old, so I don't think it's them. When I pump the bulb by hand, I can
do full speed.
I just hate to buy a new VRO for $350 and find out I still have this
problem. I don't use the VRO part anyway. It would be a huge help if
someone could let me know if I can just retrofit a different type of
Johnson fuel pump. All the others are so much cheaper, simpler and
probably more reliable!!
What I may try next is putting some gasket material around the parts
of my pump to see if that helps.
Could it be something in the crankcase? I can feel the suction from
the vacuum line, it's a pulsating suction, should it be constant? I
think it's normal anyway. Thanks for the help, I miss having a usable
boat and can't wait to get back out again.


Sorry Jarrod running out of stuff here.

Just on that using "gasket material" be aware things like silastic etc
dissolve in petrol & will just block the carbs.

As to using a different pump if it will physically fit when given a
vacuum pulse it will pump fuel but be very careful because at high power
if it doesn't get "enough" fuel the engine might run lean & that can
wreck it. Is there an outboard wrecking yard near you?? maybe get the
"correct" one secondhand & try it?? Even an electric fuel pump (should
be marine rated ......... but)

Maybe try pumping the bulb with the line disconnected from the tank(s) &
the line to the carbs off, that way once there's no fuel in the
line/pump system, you can block off the outlet to the carbs & should be
able to find any leaks as you keep pressure on the bulb. (air leaks out
much easier & more noticeably than fuel) while there's no fuel in it try
to apply some suction to each section (suck on the pump outlet with a
finger over the inlet & your tongue should hold pressure for a "short"
time, no crude comments needed:-)) Re-check the oil side is really
blocked off because the "O" ring on the plunger "will" leak.

If there are no leaks of air under bulb pressure & given you've replaced
the hoses etc so it's not sucking air at any of the hose connections???
You're happy it's not the non return valves or vent in the tank(S),
the diaphragm is OK? then;

are you sure the vacuum line is delivering a good clean pulse signal,
they have an inline valve to stop a backfire from damaging the plastic
pump; is that clear & not stopping the crankcase pulse??

Good luck

K

Welcome back!
--
John H