2000 50hp idle issue? Tilt or no Tilt

[beleau]

2000 Johnson 50hp j50plssm. After experiecing enging trouble a couple weeks ago (stalling at idle with no restart) I took it to the shop for an engine check. Compression good, spark good, fuel good, this is what they said. They suggested a carb rebuild an tune up for $595. I picked the boat up and did the rebuild myself. All seemed good on the hose. Took it to the lake and basically had the same problem; fine at top end, stalling at idle and unable to start. I did somehow figure out that if i tilted the motor up with the exhaust out of the water it started fine. I did this at the dock multiple times, at idle, let it start to stall out, tilt motor up, engine comes back. So it basically runs better with no pressure on the exhaust. (Im assuming thats what it is) When it is not having the problem it idles fine, I have it about 1000-1100 in neutral. Any ideas? Could this possibly be a fuel pump issue?

Thanks in advance for the help, I need it.

Steve

 

[tashasdaddy]

Re: 2000 50hp idle issue?

Re: 2000 50hp idle issue?

you set your idle rpms with the motor in the water and in gear. if it were fuel pump you would not get to the top end. did you remove the low speed jets and clean them?

 

[beleau]

Re: 2000 50hp idle issue?

Re: 2000 50hp idle issue?

I did remove them and clean them. I set the idle initially on the hose of course, set it a bit high at about 1200. When I got to the lake initially it idled fine, about 1000-1100 in neutral then about 800 or so in gear so I didn't adjust it any further. For the first half hour or so of running it seemed perfect. I took it through all ranges up to wot, back to idle in gear, back to neutral etc many times and it was perfect. Then I shut it down for about 20 minutes and thats when it had trouble starting again, had to tilt motor up to get it to start. Did the same thing, ran through all ranges etc, same. Shut it down and the same happened, had problems starting, had to tilt, fine at higher range. So its almost like it has the problem after I shut it down and go to restart. Got it back to dock and thats when I sat there with the hood off. It would idle fine for 5 minutes or so, start to stall, tilt motor up, motor would come back. So its almost like it got worse as I ran it more. I did try pumping the bulb when it started to stall and at first it did seem like that helped. Should the bulb be hard all the time? And should there always be visible fuel in the filter? Because as I was watching this at the dock I could see the filter slowly empty out after I filled it with the bulb. Not sure if that is normal. One more thing, any suggestion on a homemade test tank that I could use?

Thank you so much for the help,
Steve

 

[tashasdaddy]

Re: 2000 50hp idle issue?

Re: 2000 50hp idle issue?

check for blockage in fuel system, closed vent on fuel tank. air leak in fuel fittings. sticking float needle valve.

 

[beleau]

Re: 2000 50hp idle issue?

Re: 2000 50hp idle issue?

now its getting even weirder. Now it does it on the muffs as well. ie, wont start ...tilt up = start, tilt down stalls. however now if i push the primer in when it begins to stall, it comes back.

 

[tashasdaddy]

Re: 2000 50hp idle issue?

Re: 2000 50hp idle issue?

starving for fuel, dirty carbs, stuck float needle. pushing the primer bypasses the carbs, and inject fuel directly into the intake. so the carbs are your problem. BRING the motor to me i will gladly tune it and rebuild the carbs for $595. that would give me atleast a $350 profit. those carbs are really easy to do. http://forums.iboats.com/showthread.php?t=299680

 

[beleau]

Re: 2000 50hp idle issue?

Re: 2000 50hp idle issue?

well thats what I of course thought initially as well. both carbs rebuilt and seem very clean. I might add when i did them that they both looked pristine, no visible anything whatsoever. any ideas as to why it runs better when tilted up? that one has me baffled.


should the throttle plates be fully closed at idle?

 

[HybridMX6]

Re: 2000 50hp idle issue?

Re: 2000 50hp idle issue?

Just curious, did you try re-setting your idle yet? It's a long shot, but it could have vibrated a bit from where it was.
Also, did you replace the fuel hoses with newer ones made for ethanol? I'm doing my 2000 55hp commercial motor right now and am doing all hoses and both carbs, I have a miss at idle, but runs great once it gets over about 1500 rpms.
If you did not replace the hoses, or at least blow them out, you could have got some buildup from them into the carbs.

 

[countvlad]

Re: 2000 50hp idle issue?

Re: 2000 50hp idle issue?

now its getting even weirder. Now it does it on the muffs as well. ie, wont start ...tilt up = start, tilt down stalls. however now if i push the primer in when it begins to stall, it comes back.

by pushing the primer you are bypassing the carbs and dumping fuel straight in to the intake manifold... so i think your carbs are the problem or fuel pump related

 

[HybridMX6]

Re: 2000 50hp idle issue?

Re: 2000 50hp idle issue?

If it was fuel pump it definitely wouldn't get up to the top end.

 

[beleau]

Re: 2000 50hp idle issue?

Re: 2000 50hp idle issue?

well....replaced fuel lines and new fuel pump. so as of now, I have rebuilt the carbs, new pump and lines and started over about five times. it seems much better on the hose, idles all day tilted down no problem. however when i tilt up, far up, almost all the way, it picks up about 100-200 rpms. then when i tilt down it drops slightly below original idle and struggles. it will come back with the bulb or throttle. and what is even stranger is that it is doing it on both carbs. I verified this by pulling the plug wire on each cylinder and doing it. fricken strange....I'm stumped.

 

[HybridMX6]

Re: 2000 50hp idle issue?

Re: 2000 50hp idle issue?

Well, all lines are new, pump is new, carbs are rebuilt, so something is up, and sounds like it's still fuel related. Is the fuel line and primer bulb new as well?

 

[beleau]

Re: 2000 50hp idle issue?

Re: 2000 50hp idle issue?

yep, sure is. I know this one is very weird. its almost like when i change the angle on the carbs things happen, yet i know the floats are not sticking because it does it on both carbs.

 

[beleau]

Re: 2000 50hp idle issue?

Re: 2000 50hp idle issue?

well took it out on the lake today. at first all good. started right up, idled perfect, took it through all the ranges, back to idle ect, all good. ran for about 20 min, shut down for about 20 min. did not tilt up. started up good, idled fine in neutral, struggled a little in gear, fine above idle. ran for another 20 min or so, shut down for about 30, did not tilt. started up and did same as before, struggled in gear at idle. ran again, shut down and tilted up this time, sat for about 30. went to leave, tilted back down, no start. tilted up, start.

so basically now it seems that if i run at mid-upper range for any time then bring back to idle it is perfect. however if i shut down it will struggle at idle until i run it up again and if i shut down and tilt motor up it wont start unless i tilt motor up (relief back pressure i guess). what the ....