One cylinder dieing.

[henrye718]

Hello All,

Could use some help. I have one cylinder dieing when I throttle up.

The way Im doing this is disconnecting one plug wire at a time and starting then reving the engine, one cylinder runs fine when trying to power up and the other sputters and dies almost instantly (lower cylinder).

I ended up testing for something like this due to the engine not feeling like I had the right power (compression test came out good). The motor (1989 40 hp) is new to me so im not sure how fast it should go but it doesnt seem right with a 300lb 16' duranuatic tin boat and two light people, it does 19mph on the gps. It idles without shutting off but shakes somewhat.

Can I swap the upper and lower carbs around to see if the problem follows? Are they the same? Spary some gas into the carb to see if it revs right?

How about swaping around the ignition system? The coil is one piece, powering both plugs, looks like they have seperate trigger wires that I can just move too? Is the igintion system such that if one side is working perfectly the other side is fine also?

Thanks for reading and any other suggestions for diagnosing this would be great.

Some engine info: 2 cylinder, dual carbs, 1989 Johnson J40CECTEL. I have installed new plugs, cables and a new fuel hose and primer ball pump. Starts very easy everytime.

 

[tashasdaddy]

Re: One cylinder dieing.

it will be hard to swap carbs, as one has the throttle linkage on it. you can swap trigger and plug wires, and see if it changes position. read carb cleaning, and ethanol here > http://forums.iboats.com/showthread.php?p=2014566#post2014566

 

[henrye718]

Re: One cylinder dieing.

Thank you, looks like I will be rebuilding the carbs soon, for $20 a kit its a no brainer at this point.


I had already read those how-to's a while back, thank you for writing them, very informative and what a big help they are.

 

[scrampbell]

Re: One cylinder dieing.

Good advice from Tashasdaddy.

Also, you can rule out the ignition system with a spark tester set at 1/2 inch gap. Much more fool proof than switching around components, etc.

 

[henrye718]

Re: One cylinder dieing.

Pretty sure I found the problem, suspect dieing cylinder's carberator is all kinds of clogged and dirty . Other one was in perfect condition .

Is the red area a jet? if so which one?

Now I have alot of carb rebuild questions, sigh, another thread.

 

[tx1961whaler]

Re: One cylinder dieing.

High speed jet is the one in the bottom.
You really need to consider changing all of the fuel lines. That black crud is likely to be the inside of the old fuel lines that have been eaten away. I'd invest in a bucket of carb cleaner; the kind that comes in a one gallon can with a parts basket in it, and soak the carbs overnight.

 

[henrye718]

Re: One cylinder dieing.

Yes, thank you. right after I took the carbs off at the marina I measured out all the lengths of the different diameter fuel hoses, for my shopping list.

Im kinda scared of the that stuff in a tin bucket, my body doesnt react well to chemicals. I'm gona have to do it the hard way with something safer and a lot of elbow grease.

 

[tx1961whaler]

Re: One cylinder dieing.

Yes, if you are chemically sensitive, then the stuff in the bucket will make you curl up like a spider after Raid.
In that case, I'd boil the carbs in water and strong soap, like laundry detergent or automatic dishwashing soap. If that's out of the question, then dissolve baking soda. The high speed jet can be cleaned up by running a wire through it, and the rest of the carb by using compressed air.

 

[henrye718]

Re: One cylinder dieing.

Ok got the carbs rebuilt problem has switched around. Bottom cylinder runs much better, top sputters and dies when trying to throttle up.

Chaged out all fuel lines, bulb and tank hoses included. In the process I broke the following.

http://www.iboats.com/Johnson_Outbo...2260--submit.x.38--submit.y.8--view_id.271265

Then I made a quick run to the parts guys and replaced it with a OEM, I had just replace this with a sierra part. The red handle that plugs into this was also replaced with a new sierra part due to a leak. When I went to put these two back together I noticed it needed a little to much force after going in, pulled it out and sure enough Oring on the handle valve was damaged. looks like i will be going back for a new OEM handle too.

I can now flood the engine completely with fuel if I set the the primer to manual position and pump the tank bulb a good amount. I dont remember If this was possible before. Im thinking the damaged O-ring caused this or something wrong with my rebuild (float valves not sealing) but its not doing it when the red handle valve is in the run position. I was able to blow no air when the carbs were flipped over and was able to when the carbs were the other way.


Could use some help on why the dieing cylinder moved up. I didnt do much testing after it was all slapped back together. I'll try a bunch more things tomorrow and report back. Tonight I looked at the parts diagram for the carbs on the johnson site for a good while going through everything. They are put back together right and cleaned out very well.

Im thinking there are adjustments I need to do that my clymer manual does not go into. I also believe the low and high jets/orifices on these carbs are fixed, just screw them tight and its done. So my only real carb adjustment is the single SS needle valve? All linkage is exactly the same and unchanged. Motor runs very poorly now, much worse than before the carb rebuilds and the new fuel liens. With both cylniders firing it just dies on throttle up.

Any input would be greatly appreciated.

 

[henrye718]

Re: One cylinder dieing.

Ok I changed out the red solenoid handle. Checked every new fuel line I installed for leaks at the connections. Then hooked up the water hose to the motor...

It started right up and idled pretty badly tried a few times to rev her up she just died out. I let it get nice and warm on idle for 10 min restarting everytime it stalled and then tried revving again, same results. I put my hands over the carbs and let them rev that way for a good 20 seconds. Then tried again to rev with the normal throttle. It reved right up, sounded good too. Played with revving it up and letting it drop to idle for a while, no more stalls. Pulled bottom cylinder plug wire, revved engine, revved right up. Did the same for top cylinder same results.

Set idle adjustments best I could. Dropped boat in water, headed out into habor, 37 Mph on the GPS. No stalls or hard starts.

Next day cold engine in water, started right up warmed up for 20 seconds idled out of marina, Blasted off. And fished for the next 7 hours I am happy to say she runs very well now. Plenty of speed and no stalls or odd eratic behavior.

Have no idea what was wrong when I first tried to run the engine after installing the newly rebuilt carbs and fuel hoses. I would guess there was a air pocket somewhere screwing things up. Once it cleared engine started and ran like a champ.

 

[tx1961whaler]

Re: One cylinder dieing.

Good job!
It could have been air, or the cylinders might have been flooded from the primer work and needed to burn off some of the extra gas.