"K. Smith" wrote in message
u...
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
Not an answer to your problem but I'm following this thread with a great
deal of interest as my Evinrude 70hp, ca 1984 is doing exactly the same
thing. It still has the oil tank hooked up. It will idle and go about 1/4
throttle perfectly, no misses but move the throttle any further toward wot.
and it stalls out as if it ran out of gas. I've put on a new gas tank and
am going to try now the new hose and o ring. Tell me where the fuel filter
is on the engine if you would. My problem started after we disconnected
everything to install a new deck on the pontoon boat. It ran fine the
season before the redo. I haven't done anything to the carbs except drain
the fuel bowls. Found a little clean water and oil when I pulled the drain
plugs which I understand could be partly because I ran the engine with hose
disconnected until it stalled to winterize it last fall. I've also cleaned
out the oil tank and put in new oil. Fonnd some brown sludge at the bottom
indicating water had gotten in the tank. I've not tried pumping the fuel
bulb while running to see if that makes a difference but I notice the bulb
will never pump up hard when priming. Maybe an air leak or faulty
bulb/hose?
Hated to make you guys do all the work so I guess I'll have to try some
things myself now that the boat is in the water.

Tom G.

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

That's got to be it then! I saw fuel squirting out of the seam where
the large diaphragm housing is screwed to the body of the fuel pump.
This was when I had the vacuum and fuel lines mis matched, but that
tells me if fuel can squirt out then air leaks in and the vacuum
doesn't get to have the proper pull on the diaphragm. I will find an O-
ring to fit into the housing and make it air tight, hopefully that
fixes it!
I'm surprised in this design, they don't have a gasket or O-ring on
that side of the pump.

wrote in message
ups.com...
That's got to be it then! I saw fuel squirting out of the seam where
the large diaphragm housing is screwed to the body of the fuel pump.
This was when I had the vacuum and fuel lines mis matched, but that
tells me if fuel can squirt out then air leaks in and the vacuum
doesn't get to have the proper pull on the diaphragm. I will find an O-
ring to fit into the housing and make it air tight, hopefully that
fixes it!
I'm surprised in this design, they don't have a gasket or O-ring on
that side of the pump.


A ridge on the circumference of the diaphragm does the sealing between the
halves.

Tom, the fuel filter is right near the fuel pump. Just follow the
lines coming into the engine.
I'm going to try a new tank next. I've done everything else short of
a new fuel pump, but I can't see what's wrong with the old fuel pump!
I still think it just has to be an air leak that developed somewhere.