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1958 Johnson 35hp RDE-19C only goes about 10mph

T

Texjmcd77

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I never really get on top of the water. Runs fine up to about 10mph, then if I push further on the throttle, the engine shuts down. If I pull back on the throttle quick enough, it does not die. Back to 10mph. This motor has had a fuel pump conversion installed on it. No pressure needed in fuel tank. Indicator at motor has (slow, start, fast) as the throttle cable goes more forward this indicator moves more toward fast. It gets almost to fast when I get to 10mph.
 
Sounds like it is running on 1 cylinder.----Post the actual compression numbers.----Does spark jump a gap of 5/16" on both leads?
 
Sounds like a clogged jet in your carb. That's #75 in the attached diagram. I'd clean the bowl really good and remove and clean this jet. If the motor has been sitting a long time, the fuel sits in the bottom of the bowl and clogs up that jet. While you're in there, give everything a good cleaning and make sure the floats actually float and move freely.
I'd certainly check for good strong spark too. You can pick up a spark gap tester for about $10 at a chain auto parts store.
 
It has been running smooth at 10mph so I didn't think about spark. The only tester I have for spark is inline with the wire and look for a flashing light. I will pull the plugs to see if one of them looks fouled out.

The motor starts up easy and seems to idle fine if I don't let it get too slow except after running around at the best speed I can get for a while. Then, on the way back to the ramp, it misfires some while running no wake speed. I have not got into the carb on this motor yet. Sounds like I need to get in there too.

Thanks to both of you. It might be a couple of days before I get back on these.
 
After watching what happens to the motor when the throttle is increased, I found that at the very point when my problem happens, that is when the high speed part of the carburetor engages. So I decided to go that direction first. I got the carburetor off and the high speed jet was all the way closed. The manual says to back out 3/4 turn. So I did that. It all looked very clean inside the carb. Maybe I have found my problem now. I put it all back together this morning. Going to need to take it to the lake to test. Not sure when. Thanks again for everybody's help.
 
Probably your carb/adjustment
These old beasts will BARELY idle on one cylinder. That high speed jet often ends up being open 3/4 to 1 turn. Be sure to use only non oxy fuel. Make sure plug wires aren't arcing to ground. There can be barely enough clearance in some places for possible abrasions and damage. So in some throttle positions, the wire/wires could be in a position to arc to ground.
 
timguy said:
Probably your carb/adjustment
These old beasts will BARELY idle on one cylinder. That high speed jet often ends up being open 3/4 to 1 turn. Be sure to use only non oxy fuel. Make sure plug wires aren't arcing to ground. There can be barely enough clearance in some places for possible abrasions and damage. So in some throttle positions, the wire/wires could be in a position to arc to ground.
Click to expand...
High speed needle not very sharp more rounded than jet needles I'm used to. I'm ready open it but it seems like it would be very rich at 3/4 to 1 turn. I really never had to set a high speed jet before.
 
Texjmcd77 said:
High speed needle not very sharp more rounded than jet needles I'm used to. I'm ready open it but it seems like it would be very rich at 3/4 to 1 turn. I really never had to set a high speed jet before.
Click to expand...
Sorry, but I don't know what non oxy fuel is. Tell me what you think about this. The guy I bought the motor from had restored it himself. He told me to mix 24 oz. outboard motor oil to every 6 gal. fuel. Normal to me is 16 oz. oil per 6 gal. fuel. I have oil all over lower unit after running in test tank and lots of smoke. Do you think I can go back to 16 oz. oil per 6 gal. fuel?
 
Oldsaltydog said:
Sounds like a clogged jet in your carb. That's #75 in the attached diagram. I'd clean the bowl really good and remove and clean this jet. If the motor has been sitting a long time, the fuel sits in the bottom of the bowl and clogs up that jet. While you're in there, give everything a good cleaning and make sure the floats actually float and move freely.
I'd certainly check for good strong spark too. You can pick up a spark gap tester for about $10 at a chain auto parts store.
Click to expand...
Could not find attached diagram but I got into the carb (which was surprisingly clean) and found the high speed jet was seated all the way in and not backed out any. I expect that this is my problem. I won't be able to test until I'm back out on the lake. I ran the motor in a test tank today and readjusted low speed jet. Thanks for all your help.
 
I took the boat out on the lake this morning, and it ran like it should for the first time since I got it. Thanks to all of you for your suggestions.
 
Great. Non oxy fuel has a "no ethanol" posting on the pump. It is a must for collector cars, most small engines, and outboards. Also ethanol not allowed in aviation fuels. Ethanol is damaging to rubbers and many synthetic products like seals, diaphragms, motor mounts, and hoses. It doesn't end there. Its hygroscopic and aggressively absorbs and suspends water, shortening its useable life as well as weakening its ability to provide proper combustion. Oil mix is 40:1 with modern petrol based, but I run 64:1 or 2 oz. Per gallon on all my old non needle bearings, (crank bushing) motors....but ONLY say this if I'm using Amsoil pre mix 100:1 outboard oil, or Amsoil Saber 2 stroke oil. I have used Amsoil products very successfully since the mid 1970's when they were introduced directly to us, (Dad and me), by the company owner and founder....longtime family friend, Al Amatuzio. He developed his company from knowledge of synthetics use by the United States military, primarily in aviation, as he was a fighter pilot in WWII. One of his very first products was the development of high performance 2-stroke lubrication in order to clean up the Marine industry as he was an avid fisherman. I am certain that there is no one on this forum that has the experience of myself when it comes to operating 2 stroke outboard motors, as well as chain saws with synthetics. 50 years is a pretty good chunk of time, brother....
 
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