1982 Johnson 140 Won't go over 2,000 RPM At WOT

Hi All,

New to the forum and new to boat ownership (but not boating). Here's the story. I purchased my Dad's old Champion from him and he always kept it in great shape. It has a 1982 Johnson 140 on it and i had no problems last year, ran like a bat out of hell. Dewinterized it and took it to the river to race my Dad in his new boat and do a little fishing. I put her in the water and she fired right up. No idle problems or sputtering, all seemed well. Putted out of the no wake zone and got ready to throw down the hammer. Accelerated to full throttle, but she wouldn't plane or go over 2,000 RPM. Needless to say, I lost the first race of the season to the old man, and had a perplexing problem in front of me. I would greatly appreciate the help of any seadog or river rat willing to help. Thank you in advance!

J.

Re: 1982 Johnson 140 Won't go over 2,000 RPM At WOT

First things first. Do a compression, with the engine warm. OK? If yes, do a spark test. Preferably with a spark board at 7/16" gap. All OK? If yes then look at the throttle linkage. Do the plates open to full horizontal when the throttle is moved forward? If yes. Look at the linkages. Any linkages off? (could be a link to the static timing is off or broken) If no, then you need to look at carburation and fuel supply. First check your fuel supply for water. Water does not burn so well. Also if you have a VRO, check your oil supply for water as well.

The main jets are in the bottom of the carb. They may be gummed up, while the idle circuit is ok. I would recommend starting by taking off the carbs and taking off the bottom of the carb. Look inside. See any gum or crap? If yes. Clean the carbs. If no. Look at fuel supply. Check the vacuum of the fuel supply from the tank. Should be no more than 4 inches of mercury. If okay. Check the output pressure. Should be 5-7 psi.

That would be my prescribed way of checking an engine for the problem that you are telling us about. Good luck.

Re: 1982 Johnson 140 Won't go over 2,000 RPM At WOT

GOod advice above---I posted too late!

Check the spark with an air gap tester on all 4 cylinders. You may have only 2 out of 4 cylinders firing. Maybe you just have a couple of fouled plugs from the fogging oil left over when you winterized?
If all 4 wires will jump at least a 1/4" air gap with hot blue spark, you can move on to fuel. I would check compression since it's new to you, just to have a baseline idea of what the compression is for the future---also to see if there are any major problems.
JBJ

Re: 1982 Johnson 140 Won't go over 2,000 RPM At WOT

Multimech & JB,

Thank you for your quick responses. I am planning compression test and spark test for this evening. I need to pick the testers up. Any precautions you would recommend other that the obvious: cutting fuel, pulling kill switch? I checked the linkage and the throttle seems to be fully operational. I will keep you posted on the progress. Thanks again!!

J.

Re: 1982 Johnson 140 Won't go over 2,000 RPM At WOT

Just to through another idea in the mix. I was reading another thread the other day about someone having the same problem. Evrything ran beautifully at lower RPM's but it just wouldn't get much more at WOT. Turned out to be a pin hole in the fuel pump diaphram. The pump could provide plenty of fuel at lower RPM but not at the higher ones.
Just a thought

Re: 1982 Johnson 140 Won't go over 2,000 RPM At WOT

Hi all,

Squatch, thank you for your input! Here's where I stand. I performed the compression test and it was great. 120, 120, 125, 125 +/-. Proceeded on to the spark test with a tester I got at an auto parts store. I only saw a faint spark on one cylinder. I don't know that I'm doing it right (though I think a cigarette smoking monkey could probably do it). I tried it several different ways, grounding to a few different points to ensure I had a good connection. As I said, I only saw a spark on one cylinder (lower starboard), I apologize I don't know the actual cylinder number...

So I'm curious, could this be the stator? From what I've read, power packs will fail on one side and provide NO spark. am I mistaken? Thank you all for your help! :rockon:

J.

Re: 1982 Johnson 140 Won't go over 2,000 RPM At WOT

bump