:confused: Bad carb?

[whiskerchasin]

I have a 1985 Johnson 40hp j40elc0B. It will not start unless i spray premix in the bottom carb. It backfires or pops when i spray some in the top carb and does NOT start. I have pulled and cleaned both carbs 3 times over the last month (though i may be doing something wrong. i am not a mechanic but iboats and a repair manual is great help). After cranking it i pulled the plugs and the top plug is dry and the bottom is wet.

Any ideas on what could be wrong?

All suggestions are greatly appreciated.

 

[dc095]

Re: Bad carb?

fuel pump?

 

[whiskerchasin]

Re: Bad carb?

Fuel pump is brand new sierra non-vro replacement. I disconnected the lines from the carbs and i get spurts of fuel when turning the motor over.

 

[BonairII]

Re: Bad carb?

Did u crank with the plugs connected ? If they were ...then bottom cyl probably isn't firing.

 

[whiskerchasin]

Re: Bad carb?

Did u crank with the plugs connected ? If they were ...then bottom cyl probably isn't firing.

Yes the plugs were connected. about 2 weeks ago I tested with a spark-gap tester? (metal thing that hooks up and the spark jumps about 1/4 in) and there was bright blue spark on both cyls

 

[Rick.]

Re: Bad carb?

Did you set your slow speed needles? Might be a good time to check compression as well. Best of luck. Rick.

 

[BonairII]

Re: Bad carb?

Yes the plugs were connected. about 2 weeks ago I tested with a spark-gap tester? (metal thing that hooks up and the spark jumps about 1/4 in) and there was bright blue spark on both cyls

I'm having some similar issues. Bright blue spark one day...then "not so blue" the next. Test your spark again just to be sure. Test it with engine cold.....and also after it's warmed up.

 

[metriccrescentwrench]

Re: Bad carb?

When did it start acting like this? Have you checked compression?

 

[Sander]

Re: Bad carb?

I agree with Rick, if the slow speed needle is set too low it will cause problems. Re adjust your slow speed needles.

 

[whiskerchasin]

Re: Bad carb?

Rick. I have ATTEMPTED to set the slow speed needles, but dont really know what im doing. I screw them in until lightly seated then back out 1/4 of a turn, this sound right?

BonairII I will borrow that spark tester again and try what you suggested.

metriccrescentwrench (great name btw) The boat and motor are new to me and have not run since ive had it. My buddy that is a diesel mechanic did a compression check and said it was good and the #'s were pretty close on both cyls. I dont remember the exact #'s though.

 

[slag]

Re: Bad carb?

I thought low speed needles were 1-1/2 turns on these models. Maybe I'm mistaken though.

 

[whiskerchasin]

Re: Bad carb?

You sir are probably right. TBH i have no idea where i came up the 1/4 turn.

I will sure try that.

Thank you to everyone.

 

[Sander]

Re: Bad carb?

You should find the correct adjustments here : http://forums.iboats.com/showthread.php?t=167352

Good luck!

 

[Rick.]

Re: Bad carb?

Well 1/4 isn't enough unless it's worn out (LOL). My 1995 - 40 HP manual calls for 2 1/2 turns out. Not sure if that would apply to yours though. Rick.

 

[whiskerchasin]

Re: Bad carb?

Well i've come to believe that I have the fixed slow-speed orifices and not the adjustable needle valves.

 

[Rick.]

Re: Bad carb?

Sorry for the misdirection. Are you certain the slow speed orifices are clean? Still, I think it's a good time to check your compression numbers and let us know. Rick.

 

[whiskerchasin]

Re: Bad carb?

No problem, i appreciate all ideas. the orfices are clean i am pretty sure of that.

I will get a compression check as soon as i can and let ya know.

 

[whiskerchasin]

Re: Bad carb?

I still haven't gotten my hands on a compression tester. I did find out that my primer solenoid is not working, but i spray premix in the carb and she fires right up. While its running i can pull the top coil off the spak plug and the motor doesnt change at all.

Is there anything i can do to troubleshoot until i get a compression test?

 

[whiskerchasin]

Re: Bad carb?

I read about a "shade-tree" compression check that i could do, pull plugs out 1 at a time, put hand over hole and slowly turn the flywheel.
I did this and sadly there was quite a bit a difference in the amount of pressure.

i bought some sea-foam to attempt a decarb in hopes of freeing a stuck ring, but not sure how do this. the can says put directly in the air intake and run motor, but if theres not enough compression to suck fuel in on that cylinder, how would the sea foam get to the piston?

should i put seafoam directly in the head through the hole for the spark plug?

 

[whiskerchasin]

Re: Bad carb?

what do you guys think? pull the heads?