Johnson 40HP... HELP!

able2zero

Cadet
Joined
Jun 19, 2010
Messages
15
Hi,

I am new here, but have been referencing this site for a while.

I have 19 boats at the moment, 8' to 42', and I am now trying to bring a 1988/89? Bass Tracker Pro 17 back to life, and convert it to a CC work vessel. Its been sitting in the weather for 8 years I know of.

It has a Johnson 40 hp VRO, Model# TJ40DELCEO. I have it running now, just it will start half ***** backfiring/spitting when I start to give it gas. won't die b/c I can keep it running at the carbs by pumping the carb linkage. I have repaired/replaced/cleaned the entire fuel system, and the carbs are so clean I could eat my lunch off'em. (cleaned them 3 times so far).New tank, lines, fittings, plugs, ect... I had to rewire the thing and the switch is right now at stern with the neutral safety taped, and no kill switch.

Any ideas on what could be causing this problem? I don't have a compression tester, but I can make one if I knew the pressure tolerances to match with the cylinder volume. Also the top cylinder plug is wet, but not oily like the lower plug is (both are hot after running), and the lower carb does not seem to suck as much air as the upper, but blows about the same out of the plug end.

BTW, the guys here at the shop couldn't believe that I got this motor running in less than 6 hours, when it took that much just to clean out the leaves, and "trees" growing in it. like I sad, Its been sitting for a decade.

Also, if there is anything I am missing,. please let me know. I don't need this boat breaking down 10 miles out in the Gulf.
 

tx1961whaler

Vice Admiral
Joined
May 31, 2008
Messages
5,197
Re: Johnson 40HP... HELP!

Start by checking the spark at both plugs using a spark tester. It should pop a 3/8" gap easily with a blue snap.
You can borrow a compression gauge from the auto parts store.
 

able2zero

Cadet
Joined
Jun 19, 2010
Messages
15
Re: Johnson 40HP... HELP!

Both plugs have a good spark. And dam it if I didn't get japed by "BOTH" when checking! Great way to start the morning. I "almost" had to switch to decaf.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: Johnson 40HP... HELP!

compression tester are cheap. if you can afford all those boats, you can buy a compression tester. spitting back is a sign of bad reed valves, but back fire is a sign of timing being off, which would cause it to spit. suggest full linc n sinc on the motor.
 

able2zero

Cadet
Joined
Jun 19, 2010
Messages
15
Re: Johnson 40HP... HELP!

Well I spent most of the day messing with this thing.

Reeds are good, Compression is good.
I have it running smooth, all the way up to WOT. Shifts nice. I now just have to find a way to make it idle. It starts and idles, but when I rev it then let off it dies. I guess I'll just have to play with it some more tomorrow.

BTW, I won't be able to afford anything new, if I keep buying stuff I already have on hand.
 

able2zero

Cadet
Joined
Jun 19, 2010
Messages
15
Re: Johnson 40HP... HELP!

Well, after I posted my last reply, I drank a cold one, and got pissed that I couldn't figure out what was wrong with it. So I give it one last shot for the day.

GET THIS. It started right up and runs perfectly. No problems at all. I was so happy I printed out some new decals, painted, and striped it.
 

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able2zero

Cadet
Joined
Jun 19, 2010
Messages
15
Re: Johnson 40HP... HELP!

Update..........

I'm getting the whole thing buttoned up and will be test running it this weekend at lake Hartwell.

Pics from test coming on Monday
 
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