Have to keep pushing key to run

[ZSBrownlee]

Hello all, I am having a problem with my 87 40 hp 2 stroke Johnson. Boat was given to me by my grandfather but I have used this boat my entire life. When I first got it, I took it out and it ran great. Then I shut it off and fired it up again and it wouldn't get on plane. I got home and bought carb kits for the 2 carbs. I took them completely apart then let them soak. After a couple days I put them back together with the parts included in the kit. Well I replaced some fuel lines and spark plugs while I was at it. I ran it on muffs and it ran great. Took it to the water and it will only stay idling if I push in the key every once and a while, which activates primer solenoid to give it gas. I can put it in gear and get to higher rpms. It just won't stay at an idle. Really need some help here. Thanks

 

[ZSBrownlee]

Also it's pre mixed gas vro is disconnected

 

[Crosbyman]

pushing the key chokes it so I would say your have a fuel delivery issue

vent open on the tank ?

have somebody pump the bulb instead of choking it with the key … IF it runs with the bulb then you may have a fuel pump issue

you redid the carbs… so are the floats adjusted properly ?

have you tried a different fuel hose ?

connectors and carbs not leaking when you pump it up…. If you see leaks on the hose and fittings you could be sucking air also

if the carbs overflow the flow is not adjusted properly recheck

visit the boatinfo.no site for books on your motor it is FREE

http://www.boatinfo.no/lib/mercury/manuals/40-50-55-60.html#/0

 

[racerone]

Revisit carburetor work.

 

[ZSBrownlee]

No leaks when I pump it up, how do you adjust the floats? When I rebuilt carbs and primed it I heard the bowls filling. The primer bulb gets hard when priming and doesn't loose pressure. However I will try the pumping thing tomorrow morning. I work 2nd shift so I can't tonight. I'll post results

 

[racerone]

When you operate the electric primer fuel goes into the motor.-----This fuel bypasses the metering jets in the carburetors.-----This strongly suggests that carburetors need work or adjustment.

 

[lindy46]

Soaking isn't enough - you need to blow out all the passageways, and possibly use a fine wire to clean them. Get a can of spray carb cleaner and canned air.

 

[ZSBrownlee]

Something I just thought of after doing some research.....I screwed in the low speed needle valve adjustment all the way not realizing that's what it was. Could that be a possibility of the symptoms I'm having? Thanks for the replies everybody

 

[Joe Reeves]

Yep, that'll do it!

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

Note 1: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.

Note 2: If the engine should be a three (3) cylinder engine with three (3) carburetors, start the adjustment sequence with the center carburetor.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

 

[ZSBrownlee]

Thanks for the feedback Joe Reeves! I'll post my results tomorrow if I get a chance.

 

[ZSBrownlee]

So I fine tuned it to where it run well submersed in tank. But now about every minute no matter what rpm it wants to sputter out on me. Then restart it and the cycle starts over again. There is fuel getting to carbs. I pulled spark plugs and one was about black. Hopefully it might help. If any other possibilities please feel free to let me know

 

[Crosbyman]

does it die on you if you keep priming the fuel bulb …. yes / no ??

 

[ZSBrownlee]

Crosbyman yes it still dies

 

[Joe Reeves]

With the s/plugs removed, the spark should jump a 7/16" air gap with a strong blue lightning like flame... a real SNAP! Does it? Air gap spark testers are available at any automotive parts store. You can also insert a #2 philips screwdriver tip into the plug boot, then hold the screwdriver shank away from the powerhead a distance of approximately 7/16". The gap is important.

Also, check the compression... what is the psi reading of each individual cylinder?

Are you using Champion S/Plugs QL77JC4 gaped at either .030 or .040? (recommended)

 

[ZSBrownlee]

Hey sorry I haven't responded. Compression is 145 on both cylinders. I replaced the power pack and I now have more power modrangem but still isn't planing out. I'm stumped. And yes I have those plugs which are gapped at .030

 

[ZSBrownlee]

I fixed the key pushing problem by cleaning carbs again