Johnson 200 Venom VRO '96 runs out of fuel and stalls at idle

[manitou]

My '96 Johnson 200 Venom starts and runs great. At mid and higher rpm
all is well.

Model: J200STLEUB
sn: G 043113836

However, at idle and lower rpm, it runs out of fuel. It
slowly drops rpm and then stalls. If the primer bulb is pumped it will
keep running.

The fuel lines, water separator, and filters are new, all
the fuel tank and filter fittings have new nylon ratchet clamps, and
teflon thread tape, all 3/8" lines, there is no antisiphon valve, vro
tank filter is clear, oil is pumping, ran Seafoam through it, VRO/fuel pump
is two years old, as well as pulse limiter, gas tank was drained and new
fuel added, spark plugs have low hours.

From what I have read this could be a fuel filter diaphram or clogged
low speed jets in one or more carbs.

How can I pinpoint the problem, without a lot of
trial and error part replacements?

I am willing to rebuild the fuel pump and/or
rebuild or clean one or more carbs, if the problem lies there.

There is also a VRO no-oil alarm & light (have the system check gauge) at low rpm at times, but the pump is definitely working, so I think this may be related to the fuel starvation issue and I would like to get that resolved and then see if
this alarm continue before I start looking into that system.

[manitou]

Today I plan to, first, squirt some gas oil pre-mix into the throat of the carb for the cylinder where the pulse limiter connects, at idle, to check for an increase in rpms. Then I will remove and clean the needle valve and as many other parts of that carb, to see if that is it.

If not, then I'm going to open up the vro pump to check the air motor diaphram, and replace it .

If non of that works, then I'm going to an electric fuel pump and premix for the rest of the season, and take it to the shop over the winter.

Any thoughts, comments, questions, or fantasies?

[lkhartwl]

check and replace the recycle valves on the manifold that can cause the problem .

[manitou]

I'll have to figure out where those recirculation valves are. How are they related to the problem?

In the meantime, I didn't find any change in rpm squirting gas into the carbs, and it seems to idle very smooth and the right rpm when the primer is pumped. So I opted not to go further with cleaning the needle valves or anything on the carb(s) for now.

I removed the vro pump, and opened the fuel pump chamber. I found an abrasion or area on the diaphram missing the vinyl. It's about 1/2" long, and 1/32" wide, right in the crease where the diaphram is folded down. The threads in the daiphram fabric are showing through, like a bald tire. Could that be the cause of poor fuel pumping at low rpms?

Has anyone seen this before? Is it a defect in the diaphram, or wear and tear? The pump is only about two years old and has low hours.

I' looking for the fuel diaphram kit now. I'll post results.

Any comments would be appreciated.

Thanks.

[manitou]

Added my signature




Modified by manitou at 10:44 PM 7/21/2007

[ChampioNman]

Replace the VRO.