1973 65hp Johnson fuel pump issue???

[dfrants]

Got a 1973 65hp Johnson that starts right up great, idles nice. Took her out for a spin. She has plenty of power and pushes my 16' Sylvan 32mph with a 17"pitch prop. Ran it around the lake and did a couple of hole shot tests. Then headed back to the landing and as I was slowing down off plane, she died out like she ran out of gas. I checked the fuel line and the bulb was hard, like pressurized. I couldn't squeeze fuel at all. She wouldn't start till I choked her, and ran just enough to get back to the dock. Does that sound like a fuel pump problem??? or something worse???

 

[Keyboardman]

Is your tank vented?

 

[boobie]

If this mtr has any fuel line connectors on it , check them.

 

[dfrants]

yes the tank is vented, the vent was opened. It's a brand new SeaSense fuel line with OMC style connectors. I have an OMC brand fuel line that I know is good and will try that one tomorrow.

 

[racerone]

Sounds like the gas line was not connected properly at the motor.----That would be the only reason for bulb to be hard and you could not pump fuel !

 

[oldboat1]

Overheated? Have you tried it again after that episode?

 

[dfrants]

not yet. as soon as the engine stalled I lifted the cover and felt the block. It was warm but not too hot to touch.

 

[oldboat1]

That's good. Back to fuel or ignition (compression test to see what you have).

Could be a fuel issue (old fuel, maybe water contamination).

 

[dfrants]

did a compression test...125 top, 125 middle, 110 bottom. Looks like the head gasket been replaced so possible rebuilt at sometime back in the day? what kind of behavior would uneven compression have?

 

[oldboat1]

Can be a number of issues -- stalling among them. Also difficulty getting it tuned and running smoothly.

May not have been a rebuild. Might want to pull off the head cover and replace the gasket. Check for damage (scoring, broken ring). But the compression fix might be as simple as resurfacing the head and replacing the gasket with proper torque. Relocating a tell tale elbow to the top is recommended on some to avoid cooling problems.

 

[Taylor9988]

Is there a possibility there is a clogged main jet in the carb or a needle and seat issue? Fuel filter?

 

[dfrants]

so it was running idling good at my place in a test barrel. I tilted her up and headed to the landing. put her in and started her right up. that's one thing that is very impressive about this old motor...it snaps off and starts like right now! but when I put her in gear the advanced the throttle she bogged down for a couple of seconds then took off like a raped ape. ran her around the lake a few times and thought I got er fixed, then she did the same thing as last time and died out before getting back to the landing. had to choke it to get it running again and brought her in.

 

[oldboat1]

Everything is apparently still on the table. Think I would start ruling out some systems or issues, and maybe hit on a solution in the process.

Try borrowing a known good tank and hose assembly -- see if that is an improvement.

The fuel pump is still in the mix, and you might open it up and check the diaphragm for holes or tears. It should be flexible. If it has taken on a set (sometimes has a texture similar to cardboard), replace it.

Pull off the head cover and inspect the bottom cylinder, as discussed earlier.

Check the fuel connector at the engine, and all fuel lines and connections. Repair or replace as needed.

Rebuild carbs (disassemble, soak, install kits). Radjust needles after rebuild.

Check spark on each lead with a spark tester -- measure it at somewhere around a half inch. When the motor wants to go into its stumble, pull off plug wires one at a time (I would start with the bottom plug) -- see if there is any change. No change means that cylinder likely isn't firing.

(You might choose a different order, of course. Do the simple stuff first.)

 

[dfrants]

Thank you for all the great advice. I took the carbs apart and found a very small piece of old fuel line in the top carb idle jet, the one on the side of the bowl. after test her again I now believe the motor is flooding out at idle. it takes awhile but eventually her will slowly idle slower and die out. when tis happens the plugs are wet. thinking it a needle/seat float adjustment issue?

 

[oldboat1]

Let's see -- fixed jets on that motor (my mistake in referring to needles). I don't think you can tell much by whether the plugs are wet, but suppose it's a matter of degree. Dry would be an issue.

Not sure where part of a fuel line showed up (sounds pretty bizarre). Make sure the jets are perfectly clean -- usually means soaking the carb parts, then blowing out with carb spray. Float needle and seat should be cleaned or replaced, using the wire clip if the needle has the black tip. Use the nozzle gasket, and make sure the float is not upside down.

slowly idling down to a stall can be either a rich or a lean condition, unfortunately. You may be right thinking it's a rich condition. For idle issues, though, I would think you might be running lean (would suspect partially blocked idle jet). Also can't rule out fuel pump issue -- diaphragm might be intact, but lost flexibility. I believe that issue affects idling more than high speed, but just based on what I found with a few of mine.

 

[dfrants]

did a spark test. all three cylinders tested good. I got a good blue snap at a half inch on the tester.

 

[oldboat1]

When running, try spraying some carb cleaner around the base of the engine and around the intake manifold joint (block off carb from spray). See if rpms change -- would indicate a seal leak.

 

[dfrants]

I just realized yesterday that some previous owner changed the settings for the timing. I'm guessing the since she wouldn't idle he moved the settings forward(tightened) to make the motor run faster. So I'm now trying to get the settings back to where they should be

 

[boobie]

If you want to play with the timing go to the top secret file at the top of this forum and look up the " Joe Reeves Method ". Never have to get it in the water.