A On going Problem

[Phunahm]

Fuel line to engine has been replaced all threaded fitting were sealed by me, and all new bulb fuel lines including carb to carb were replaced, tank was removed and flushed, the rechecking of carbs i dont think they are the issue because carbs were rebuilt long time ago for this issue and last summer again by me same results...

 

[Phunahm]

well gonna be in the 40,s Sunday here Ill try Dukedogs suggestion but it will be on the hose see if that rough idle improves........

 

[Phunahm]

I advanced the timing at idle to 9* runs some what better but idles at 1150-1200 on hose. temp guage at halfway point rpms at idle seems too hi??

 

[Dukedog]

wouldn't get to concerned with either till ya able ta tinker with it under a load/water pump full..........both should change slightly.....were ya able ta see tha reeds

make sure your temp buzzer/horn works.....

 

[Grub54891]

Nobody talked about crankshaft seals, good place for an air leak. Wish I could help more.

 

[Phunahm]

No i didnt dig that far (reeds) I want to do the easiest first.... i have all the gaskets i need to change them. I might just cuz of the age of engine... I dont know

 

[sutor623]

Nobody talked about crankshaft seals, good place for an air leak. Wish I could help more.

I'm with you on this. I actually did mention crankcase compression which was overlooked. I think the carbs need to be pulled again and the reed valves checked. But, normally if a reed is shot it will spit fuel from the corresponding carburetor.

Maybe he could take some carb cleaner and spray around the block sealing surfaces to see if he can find an air leak. Idle surging like this and weak hole shot is classic 2 stroke air leak.

 

[Phunahm]

Nobody talked about crankshaft seals, good place for an air leak. Wish I could help more.

I did check for leaks around block, actually one of the first things I did, been so long ago I actually forgot to mention......Sorry. At this point I think its the timing, because I never thought about (in removing the Idle stabilizer)that I would have to change the idle timing also :facepalm: ...."Thanks Dukedog" for that advise ... And it did run a lot better and fired right up in 35 degree temps....I'll probably go ahead and throw some CCM reeds in.....

 

[Phunahm]

Have you tried to connect to a remote fuel supply to rule out an air leak in your fuel tank?

Have you tried the cylinder drop test at idle? Pull the spark plug wires one by one and see if all CYLINDERs act the same when you pull the wire. (Disclaimer* Wear gloves and dont shock yourself!!)

On another note, I was chasing my tail with an issue similar to this and ended up having scored piston skirts and cylinder wall on one cylinder. BUT, compression numbers were perfect. Even passed a leak down test. Go figure........... I would think that you either have air entering from the boat side fuel tank or there is a minor mechanical issue in the block affecting crankcase compression at idle. Do you have access to a bore scope by any chance?

I do have a bore scope. Sorry i did over look your earlier question.....

 

[Dukedog]

any little hesitation and/or slight stall is usually a timing or carb (inside and/or outside gasket general culprits) issue of some type.. but then again its merc so nothin' can be ruled out!... seen 'em do some really weird things over tha years..... jus remember tha book idle timing numbers aren't cast in stone... gl with it.

 

[sutor623]

jus remember tha book idle timing numbers aren't cast in stone...

If that ain't the gul durn truth right there!! I think its hard to nail it with outboards because the same 48hp pushing a 16' tinny 33MPH could be on a 24' 'toon puttering along at 12MPH at WOT. With a load margin that significant it's hard to say what idle timing would need to be at!!

 

[jimmbo]

I would take another look at your fuel pump. Particularly the check valves. You said the primer bulb would go soft, then hard when the engine was acting up. Primer bulbs only get hard if there is no flow into the engine. If the fuel pump inlets wasn't sealing it might be sending enough fuel towards the tank to firm up the primer bulb. I know the primer bulb is supposed to flow one way but... if the outlet valve on it isn't perfect fuel can get in.

 

[quicktach]

Sounds like a lagging advance problem.

 

[Phunahm]

Sounds like a lagging advance problem.

I dont really understand your term "lagging advance"

 

[Phunahm]

I would take another look at your fuel pump. Particularly the check valves. You said the primer bulb would go soft, then hard when the engine was acting up. Primer bulbs only get hard if there is no flow into the engine. If the fuel pump inlets wasn't sealing it might be sending enough fuel towards the tank to firm up the primer bulb. I know the primer bulb is supposed to flow one way but... if the outlet valve on it isn't perfect fuel can get in.

Ive rebuilt pump 3 times already.... It might be four times because I just ran across another R&R kit in my garage.

 

[sutor623]

I dont really understand your term "lagging advance"

Sometimes the trigger can be sticky and need a good greasing at the base. If it doesn't keep up with the throttle position is it "lagging."

 

[Phunahm]

well new CCM reeds are installed do a sync and link then wait till no ice on lake Ill time it and see where we are.....

 

[quicktach]

How were carb needles and seats when you did carb work?

 

[Phunahm]

How were carb needles and seats when you did carb work?

I replaced the needle and seats...

I do have a Update: It finally got in the 60's here and was able to fire it up on the hose I primed it turn the key not hardly a full stroke she fired right up no sneezing, misfires or anything , less smoke now and sounds great! Its idling at 1150rpm on the hose. I have a video but I cant figure out how to post it.... All i need now is open water(ice still on lake) then I can fine tune