What next?

[htr2133]

so I completed my first diy carb rebuild and fuel pump rebuild. I also installed an in line fuel filter under the cowl. Took the boat out and it starts and I got the idle adjusted, but it won't run past maybe half throttle. It's like it's governed or something. Could this be because of the fuel filter restricting fuel flow? Or is this a sign I did something wrong?

73 Johnson seahorse 6hp. Used all oem parts and I followed the fuel pump rebuild instructions very, very carefully. Felt pretty good about the carb rebuild. I did not soak the carb in a dip and could not get the high speed jet out, but did spray/clean thoroughly 2x.

 

[F_R]

That nearly always is caused by running on one cylinder. Disconnect and ground one spark plug wire and see how it runs. Then do the same with the other one. If I am correct, it won't make any difference with one disconnected, but won't run at all with the other one disconnected. That is the good one. Now find out and fix whatever is wrong with the other one. Could be as simple a bad spark plug, or possibly dirty breaker points, bad coil, condenser or plug wire. Venture to say it is not the carburetor or fuel pump.

EDIT: Somebody else will say this, but I'll say it first. Make sure you have good compression on both cylinders, and no water getting into either one.

 

[racerone]

Agreed , pull the flywheel.---You will likely find 2 cracked coils or 2 new ones already.--Did 5 of these motors over the winter and there are 10 new coils on them now.

 

[htr2133]

Thank you both for the responses. I did pick up a spark tester; I assume I can perform the same test as mentioned above with the spark tester? I hope this is not a dumb question, but how can I check for water in cylinders? Milky substance on plugs is the only test I know of.

I should also add that the motor has not run correctly at high rpm for a couple of years. It would surge at high rpm, not really a miss, just a surge and consistent run about 3/4 throttle. Everyone, including me suggested Carb first, and I needed to rebuild fuel pump bc it was leaking. This is how the motor was running the first 5 or 6 trips in March/April this year as well. Then, one trip, it wouldn't even run that well and once it died, I never could get it started. Did carb and fuel pump and now it will start and idle but will only run half throttle. Does that info change anything regarding your recommendations above?

Thanks again!

 

[gm280]

WOW so many things really need tested and checked. As usual, start off with a quality compression test and see if all cylinders are good and within 10% of each other. If so, then proceed with the spark tests and make sure you can jump a 7/16" gap with a good quality blue colored spark on each cylinder. If that is good then move to the carb. And buy a carb kit and disassembly the carb, soak it in some good cleaner and blow out every passage and reassembly again. Make sure the float is set correctly and that the low AND high speed jets are clean and tight. If all that is good, you have a fuel delivery issue beyond the carb...

 

[htr2133]

Thanks, a quick update: I just tested for spark on both cylinders and could not get a spark at all? Not that I could see anyway. I even turned the light off and got the gap smaller and smaller trying to see any spark and could not. Can this be right? Surely there is some spark or it would not start and run at all, right? I am picking up a compression tester tomorrow to verify cylinder pressures. I am very bummed that after the carb rebuild and fuel pump this little motor didn't start acting right.

 

[boobie]

Are you using the spark tester correctly ?? Plug wire on one end and the other grounded.

 

[htr2133]

Yes, I tried several areas on the engine to make sure I was getting a good ground. I also made sure that the plug wire was all the way down on the end of the tool for a good connection. Still, I can't imagine the spark being that weak.

 

[F_R]

With all due respect to the previous post, 7/16" gap for the spark is awfully optimistic. 1/4" is more like it. That is not CD ignition in a '73

 

[htr2133]

Ok several follow up ?s here guys:
1. If the motor was running on one cylinder wouldn't it be noticeably jumpy with vibration? The thing runs pretty smoot right now.

2. How do I ground the spark plug wire while running the motor? Can I just use my spark tester to do so?

3. How can I check for water in the cylinders? The plugs don't look milky.

4. I reached a crab rebuild video and the guy stated the float should be parallel or set level w the bowl body. Mine was close but the float was on a slight angle upward. Could this be causing a restriction of fuel into the bowl preventing the motor from full rpm range?

5. Does it matter what bolt or part of the motor I mount my spark tester clamp on? I still can't detect a spark at even an 1/8 or 1/6 of an inch. But the motor starts, idles, and runs about half throttle all day long.

Thanks.

 

[htr2133]

I did just test for spark again and was able to get spark on top cylinder only. Never could duplicate in bottom cylinder.

 

[racerone]

???---Posts # 2 & 3 suggest to you to pull the flywheel to do an inspection.----Here we are at post # 11 and you appear to doubt advice from folks with years and years of experience on these motors !!

 

[htr2133]

Just did compression test. Both cylinders were between 40-45 psi. If I had to say 41 and 43. Hard to tell w the gauge I had. Is this normal? I know they are close enough but just curious about the compression.

 

[htr2133]

Hi racerone; I do not doubt the advice at all and am very appreciative. I haven't had time to pull the flywheel yet. There were other suggestions also (compression test, spark test, test for water, etc) and tests that I could perform quicker and have done so. My purpose in continuing to post was to show results of the steps I have taken. I have also asked for clarity on a couple of the suggested tests. I'm sorry if I appear to doubt the advice; I am new to working on these motors.