johnson 40 hp

[Paul Moir]

Re: johnson 40 hp

Throttle position does not matter, that's completely arbitrary. What matters is that the throttle butterfly valve on the carb should *just* begin to move when those line up. You want to exaggerate the movement of the butterfly valve shaft by attaching a wire on it. The service manuals recommend crimping a stiff bit of wire into an alligator clip which you then attach to the shaft.<br /><br />I think once you get that needle secured your sneeze will go away. Do you have the packing nut which goes over the threaded part of the knob? Have you tried tightening it? If the knob is loose at all it'll leak air and cause lean running.

 

[rod087]

Re: johnson 40 hp

Hi there i checked the packing nut and yes there was no packing left in it so i put a o-ring in it and it seems to work fine and running alot better it did backfire throught the carb and it did backfrie out the exshast a couple of times also untill i adjusted the needle, but it seems to be laboured when it is idling.I was going to try and do the link/sync but the rod where the remote cable hooks up to the shaft that goes to the top of the engine there was a little peice broken so there was alot of slop in the mechanizim, so i fix that and was going to adjust the throttle cam so the marks line up with the pointer on the intake and then do the link/sync.After that if all is fine i would like to put the timing light on it, and i read before that the flywheel marks should be in the middle of the marks on the mag plate, but at what throttle postion or rpm should that be set at?<br />Thanks<br />Rod

 

[rod087]

Re: johnson 40 hp

Well i thought that i had cured the backfire problem but no it is still backfiring throught the carb, does anyone have any suggestion besides bad crank seals?<br />THanks<br />Rod

 

[rod087]

Re: johnson 40 hp

I did some more checking today and the timing plate is quite lose and moves aruond so i think that ill have to fix this.What is in there is it a bushing or what that can be change?<br />Thanks<br />Rod

 

[Paul Moir]

Re: johnson 40 hp

There's the Joe Reeves wobbly armature plate fix, which works very well and costs nothing:<br /> http://forums.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=28;t=020981 <br /><br />

<br /><br />With the timing light check, it does not matter what the throttle position is or what RPMs the engine is turning because the armature plate where the marks are turns with the throttle.

 

[rod087]

Re: johnson 40 hp

Thanks Paul we did check the timing and it was a little out it was line up with one of the marks instead of in the middle of the marks.As far as the wobble in the armiture plate do you think this could be the reason for the backfire problems that i am having or is it likely something else?

 

[Paul Moir]

Re: johnson 40 hp

It's worth a shot and it could certainly be the cause. At the very least it'll make the engine run much quieter. If you warp the ring too much then the armature plate will be too stiff to be turned by the spring that pushes it. If that happens, then simply take the ring off and flatten it out a bit.<br /><br />If you have a bad crankcase seal, it'll turn up as different markings on the firing ends of the the spark plugs after idling a bit since it'll affect one cylinder more than the other. At full throttle it'll usually hardly make any difference. The bottom crankshaft seal is rarely an issue on these, but unfortunately it's very hard to check. <br /><br />If the top seal is leaking, you'll find oil all over the ignition coils and flywheel. Also, you'll likely be able to see where it's bad. It can be changed out without disassembling the engine.<br /><br />If you've got the marks lined up (even if it's at the edge) you've set your points very well. Don't bother trying for better, you'll gain nothing.

 

[rod087]

Re: johnson 40 hp

Well i tightend the armature plate and put it bake together checked there is spark at both plugs but it wouldnt start at all, i sprayed a little gas in the carb and still wont fire up when i checked the plugs the one was wet so i dont know if it is loaded up on fuel or what but you would think it would fire at least the one plug was dry.This is starting to get quit frustrating.<br />Thanks<br />Rod

 

[rod087]

Re: johnson 40 hp

Can anyone out there have some idea whats wrong now it has spark and i sprayed a little gas in the carb but it doesnt fire at all,i dont know what to try next.<br />Thanks<br />Rod

 

[Paul Moir]

Re: johnson 40 hp

Got sparks 3/8" long? If so, it must be a fuel problem. Try putting a lot of fuel down the carb's throat, and if that doesn't work, spray a shot in each cylinder and try cranking it over.<br /><br />Oh, hey, you don't have the spark plug wires on the wrong plugs do you?