1995 johnson 15hp. J15retb. Cant get to start?!

[Superduck1]

So started the year and things worked fine. The more I took it out the worse it has become. Sometimes upwards of 50 plus pulls amd it still wont start. It will shudder and then die. Back to more pulling. So far I have put new plugs in, took the carb off amd replaced gaskets and throughly cleaned with carb cleaner. Fresh premium gas with marine oil. Really the only way I can sometimes start it is with a bit of gas down the carb. I'm at loss of what to do or try.

 

[racerone]

A 1993 model perhaps.-------Well 50 pull clearly says that something is wrong.-------So post your compression numbers here.------Does spark jump a gap of 3/8" or more , yes or no.-----Does manual pump go hard , yes or no?----Does spark advance slightly and does throttle open slightly when tiller handle shows " start " position.

 

[oldboat1]

Not sure you carb work was complete -- lots of variation in methods. Can't cut corners.

Start with spark test (above).

 

[iggyw1]

It appears to me that the carb "cleaning" needs to be re-visited. When you cleaned the carb, did you clean all of the ports with a thin wire, like the cord from a weed whacker, remove any welch plugs and clean the ports and all passages underneath them? Did you soak the carb body in a carb cleaning solvent? Carb cleaning is much more than changing the gaskets and spraying Gumout into the carburator body & parts.

 

[Superduck1]

I do not have the compression numbers, the gap is less than 3/8. Throttle does advance in the start position, not sure what spark advance is? Carb cleaning involved complete removal and replacement of parts. New main jet in addition to gaskets. Used thin copper wire and went through all ports gently after soaking in carb cleaner. Everything that could be removed was and gone through.

 

[racerone]

But a good ignition system can jump a gap of 7/16" or more with a " snap " you can hear!-----So does spark on your motor jump a gap of 7/16" , yes , no or no idea why you should do that test ?

 

[Superduck1]

The gap on the plugs is just under 3 mm. Or is this gap you're talking about somewhere else?

 

[oldboat1]

My cue to jump in. Open air adjustable tester, about $10 or so at an auto parts store.

 

[Superduck1]

I'm a bit of a novice to all this, what exactly does that do? Also was able to get running byvpriming the carb with starter fluid.

 

[racerone]

Seeing spark on a plug is not good enough.----You want to test maximum ignition output and health of the system.----Therefor you need a test device !!

 

[Superduck1]

Gotcha. How do I use that device to test that?

 

[OptsyEagle]

Set the gap to 7/16". Put the spark plug boot on the one end and clip it to some metal part of the motor for a ground and pull on the starter rope and look to see if a spark jumps across the gap. You may need to be in a darker room to see the spark but that is the basics of the test. If you don't see a spark, close the gap a little and see if you get one. That info can be useful as well.

 

[Superduck1]

I have spark. The gaps are currently set to where the old ones which is 2.8 mm.

 

[oldboat1]

Proper plug gap is typically .030 inches. (.762 mm ?) But it sounds like you are not trying the spark tester to test ignition strength. The gap set on the tester will be much greater than plug gap (at 7/16 inches).

Set the tester at 7/16 inches and clamp it to a solid ground on the powerhead. See if you get spark, Assuming the tester shows you the ignition is doing its job, set the plug gaps to .030 inches and see if the motor fires up.

 

[racerone]

You are looking to test maximum voltage output on that motor.----The ignition on that motor can jump a gap of 12 mm if in good condition !!----Many folks do not appear to know that it does takes more voltage when sparkplug is in the cylinder , and air is compressed at 120 PSI in the 0.030 / 0.040" ( 1 mm ) plug gap !!

 

[Sailpower]

I've just had an unusual experience with my 1994 Johnson 9.9 - it became difficult to start and wouldn't tick over - had to keep it over 1500rpm. Needed a bit of choke to start it then keep the revs up.
All the advice was a blocked idle circuit which seemed to make sense, but after 2 carb cleans and refitting it obviously wasn't that - so I checked the plugs - all OK but one was a bit oiled up. The compression was around 90 on both so I was happy with that - then checked the double coil according to the manual - one was completely out of spec - but it still provided a spark even when testing it to jump a gap? Anyway, replaced the coil and it ticks over beautifully now and starts easily.
Basically leave no stone unturned - check everything however unlikely it may seem.

 

[Superduck1]

Sorry for the delay. I got the testing tool, and I got spark at 7/16th. I did notice when i pulled the lower spark plug, it was damp and didnt look like it was burning fuel compared to the upper. No burn Marks.

 

[racerone]

Does the manual fuel pump go hard , yes or no ?-----What are the compression numbers ?----Post them here.----Have you inspected fuel pump diaphragm , yes or no.------Believe it or not if you answer questions we can lead you to where the problem is !!

 

[Superduck1]

Have not checked compression yet. Have not inspected the diaphragm either.

 

[racerone]

Sorry -----But pulling it over 50 times tells me there is a problem.----The trouble shooting is simple and nobody here can see / hear / feel your motor.----Or bring it over I think it is easy to figure out what is wrong here.