Strange problem on Johnson 40HP 1996

[leotzian]

Hi to all again
I had fixed my engine with your help in my previous post.
http://forums.iboats.com/showthread.php?p=2884797#post2884797

Now I have a new problem
As I write before I had disable vro with the steps you recomended.
This problem happened twice, when I have 1 week to use the boat , ( I have it at home in a treiler ) when I start the engine, ( it starts fine ), and try to open full trottle, the rpm is limited in about 3000, no alarm, no light on the panel, this happens about 5 minutes, after that the engine suddenly starts running like a charm, as many hours as I want to use it no problem WOT at about 5500-6000rpm.
Second time tried to use it exact the same problem.This time I tried this. I let the engine in the sea in the dock, and I was using it every day for four days ( I was going fishing ) for 3 - 8 hours every morning the engine was perfect, no problem at all

I don't know what to think.
I think SLOW was activated, but why? it happenes only with cold engine
I had tried to ground the tan wire comming from the heat sensor, only the "hot" led lights.
But when the problem occurs no light at all.
And another question, is it necessary to warm up the engine 5 minutes before I open full trottle?

Thank you in advance
Leonidas

 

[Joe Reeves]

Re: Strange problem on Johnson 40HP 1996

If your engine has the S.L.O.W. feature, grounding the heat sensor wire would activate that feature..... don't do that. And no, it's not necessary to warm the engine up before hitting full throttle.

What spark plugs are you using, and at what gap?

With the engine being cold and the problem existing, check the compression, and with the spark plugs removed, check the ignition (spark). The spark should jump a 7/16" gap on all cylinders with a strong blue lightning like flame.... a real SNAP!

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:

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[leotzian]

Re: Strange problem on Johnson 40HP 1996

Yes my friend my engine has SLOW, I had grounded alot of days before the heat senson cable to see if the hot lights on.
As for the spark plugs, I bought them from the dealer in Greece, are Champion QL78YC Marine, I didn't checked the gap, I put them as I bought them.
I didnt' checked the compression ( I don't have the instruments to do so ), and the spark is very good and not electricasl leaks.

How do you explain, that the engine was working fine for four days, that I had it continiously in the sea, and working it every morking for several hours? ( read my post above )

 

[Rick.]

Re: Strange problem on Johnson 40HP 1996

I've got a 1995 - 40HP and I have experienced a similar condition with it. What I've determined is that one cylinder is flooded and it takes a few minutes of running to dry it out enough for it to fire. When this condition happens it is like the SLOW is in charge but for me it has been a flooded condition it one cylinder. Best of luck. Rick.

 

[leotzian]

Re: Strange problem on Johnson 40HP 1996

Perhaps you are right

The truth is that the one tube in the top of one carb that comes from the choke was eaten by mice and I had added a tube with a bigger inside hole the original tube was I.D 2mm O.D 6mm, perhaps this supplies one carb with more fuel in prime mode