Trying to keep a 40hp Johnson running

[fintek9]

Need a little input on this one if one can give!
Friend has a 40hp Johnson (1994) Model # J40TLERE on his pontoon. His permanant gas tank is sinking in on top which allowed standing water to get in throu the dry rotted seal for the gas gage(fixed now) which in turn got water in his carbs (I took off carbs and cleaned, tank was also). He had a new gas line and primer bulb installed last year at winterization time. I hit the key prier to putting the carbs back on to clear the fuel pump if any water made it's way in there(pump worked). Primer bulb will not firm up but getting the carbs sprayed with gas and after priming the fuel line it fires up, runs like a dream but as you bring it off the fast idle into nutrual it will die as if not getting fuel and not start up unless you spray the carbs again.
(Normal start up..fast idle forward a bit, key to choke, push for 10, key to on.)
I'm picking up a new primer bulb today, the tank is vented, is there anything I'm missing thinking the problem is in the bulb itself not keeping pressure in the lines to keep feeding the carbs?
Thanks much, any thoughts would be great.

 

[fireman57]

Re: Trying to keep a 40hp Johnson running

The bulb will soften when the engine is running. Sounds like you have an air leak. Check all connections and the o ring in the ends of the fuel line where they plug into the tank and engine. When it starts to die try pumping the primer bulb and see it picks instead of spraying the carbs.

 

[fintek9]

Re: Trying to keep a 40hp Johnson running

Thanks fireman,
I do know the bulb goes soft after fire up, but does not get firm at all! barely spits out the end when you push the ball in on the end.
I thought it was funny that the tank end has no quick disconnect! it's just hose clamped to the elbow going into the top of the tank. I asked him if it had one on the old hose before he had the new one put on at the marina? he did not know.
But would that effect the stalling problem when put into neutral? I will go tonight and check the 20 amp fuse as I did not hear the telltale "click" from the starting circut, get my brothers compression gage, and once again go thru the lines between the pump and the carbs.

 

[fireman57]

Re: Trying to keep a 40hp Johnson running

Anytime you are drawing too much air it will affect the running. It creates a lean condition which is not good on your engine. As long as the clamp and hose are tight it shouldn't draw any air. I just hooked my line straight into a 10 gallon tank but still need the connector for the engine. Still sounds like you have an air leak. If your fuse is fine make sure you clean all your electrical connections.

 

[fintek9]

Re: Trying to keep a 40hp Johnson running

Might be a silly question but if that air leak is in the tight cluster of tubes between the pump and carbs can one like checking a leak on air piping or nat gas spray a solution of liqiud soap and water in there lightly while the engine is running being careful not hitting elec componates and the such to see bubbles?? anyone ever try this method? or would it work touching the hose ends with that same soap solution dipped Q-tip?

 

[fireman57]

Re: Trying to keep a 40hp Johnson running

If you have any doubt about those hoses you need to change them. If there is any brittleness or cracking you are just asking for problems. A lot of hoses break down from the inside and you will have all kinds of crap in your carb(s).

 

[fintek9]

Re: Trying to keep a 40hp Johnson running

I was just walking away thinking Duh..It would draw the solution IN if there was a crack!
I'm thinking the same as you just said...Just change em, The idle tube on the top carb was cracked at the nipple anyways, I just cut it to fresh and put it back on.

 

[fireman57]

Re: Trying to keep a 40hp Johnson running

Hope that was it. Make sure you let us know.

 

[wilde1j]

Re: Trying to keep a 40hp Johnson running

Your immediate problem is a fuel delivery problem, which can have a number of causes, such as:
. air leak on pump suction side (bad clamp, cracked hose, cracked tank pickup tube, etc., etc.)
. malfunctioning anti-siphon valve
. plugged tank vent
. trash blocking tank pickup screen
. plugged fuel filter
. collapsed fuel line
. check fuel pump output by taking off outlet hose and cranking engine over (make sure it can't start). You should see long, strong pulses of fuel. If not, pump is bad.

 

[fintek9]

Re: Trying to keep a 40hp Johnson running

fuel pump connections..checking tonight
anti-siphon..ie..primer bulb( i assume )...picking up new one tonight
tank vent...good one!..will see if any mud wasps or the such plugged the puppy up.
tank pickup screen.... is clean.
fuel filter.... is clean.
fuel line....checked it when the carbs went back on yesterday, looked good with no pinch
Cranked the motor over before I put the carbs back on to see if fuel pump worked..had real good pulse

 

[fintek9]

Re: Trying to keep a 40hp Johnson running

Thanks guys for your input. with the check list I put together from you two and from the "similar threads" below I got it going strong.

Besides getting the carbs & fuel pump & gas tank free of water, There was a dried cracked fuel line to the upper carb. His tank vent mounted on the side of the boat was turned so the vent was pointing upward and was full of crap, and the primer bulb was no good (even being fairly new) With a new primer bulb getting gas to the carbs it's all purrrrin like a kitten.

It idles in nuetral now so all of the above had to be insinc.

thanks again fireman and wilde, He can now start his summer on the lake and not be tied to the dock.

Tim

 

[fireman57]

Re: Trying to keep a 40hp Johnson running

Glad to hear it. Don't be a stranger, hang around for a while.