Sputtering out and dying

[jitterbug127]

I have a 1976 Johnson 25 HP outboard. It continues to sputter out and die even after testing and replacing parts. I converted it over the the universal magneto from the low tension magneto because I have all the extra parts (and I like universal magneto better). Motor has brand new points (i filed before installing) and condensers. I thought the front coil was bad due to it appearing to have intermittent spark. I replaced the front coil with a couple different coils from my spare parts box. Still having same issue where it will run for 10-30 seconds and die.

My next thought was fuel pump. I replaced the fuel pump with a different one i was 100% sure worked. No resolve. I took carb apart and it looks spotless and has a OEM rebuild kit in it. Friend of mine actually cleaned carb a few months ago. I think its good to go.

Compression is 115/115. Spark will jump a 5/16" Gap with ease. This motor will start basically every single time I pull the rope. It wants to die after 30 seconds or so.

 

[jitterbug127]

Oh my question...What to check next? Im beyond where I'd normally repair. The timing on this motor is properly set.

 

[Crosbyman]

sounds like fuel starvation ..tried an other tank/hose ?
does it die if the tank is lifted above the motor ?
if you hand pump does it die also ?
any air leaks trying to suck gas.
does itdie idling only or HS also ?
venting OK ?

 

[jitterbug127]

sounds like fuel starvation ..tried an other tank/hose ?
does it die if the tank is lifted above the motor ?
if you hand pump does it die also ?
any air leaks trying to suck gas.
does itdie idling only or HS also ?
venting OK ?

Fuel Starvation was my thinking as well. The tank and hose are the same ones I use on my boat with my 1969. I fished it for about 3 hours straight yesterday, so I'm really confident the tank/hose all work well. I tried hand pumping bulb did same thing. Ive only run motor in barrel, but it would actually die at idle and HS both (HS being like 25%-50% throttle). I think it is venting ok as well.

 

[jitterbug127]

I think I've got a spare tank and hose in my shed. Ill get them out see if any differences in performance.

 

[Grub54891]

Even new condensers can be bad right out of the box.

 

[saltchuckmatt]

After it dies what do the spark plugs say to you...."we are wet? Or, man we're dry!"

Does it lean sneeze and die or other.... Try choke or cupping carb/fuel spray?

Right now you are guessing and throwing parts at it, you sound desperate.

I'm sure Mr Wilson will chime in soon.

 

[jitterbug127]

After it dies what do the spark plugs say to you...."we are wet? Or, man we're dry!"

Does it lean sneeze and die or other.... Try choke or cupping carb/fuel spray?

Right now you are guessing and throwing parts at it, you sound desperate.

I'm sure Mr Wilson will chime in soon.

I am always desperate...this isn't exclusive to motors. This motor is going to be a keeper for me (my back up) so everything being new is ideal. I don't mind putting new parts in to have her muddy river worthy.

I will shoot a video and post it to youtube this evening. It will die if i leave choke on too long. It fires right up strong. I feel like the ignition system is dialed in well. It has strong spark and I set the timing properly.

 

[jitterbug127]

I've got a spare carb that I was gonna swap on but its the wrong linkage.

 

[Crosbyman]

if you put your head in that barrel long enough you will die to....

ckoking does the same ...kills it drowns to engine and stop the inflow of air to mix with the fuel...

and don't hight speed it in a barrel !! it is not going anywhere.

 

[jitterbug127]

if you put your head in that barrel long enough you will die to....

ckoking does the same ...kills it drowns to engine and stop the inflow of air to mix with the fuel...

and don't hight speed it in a barrel !! it is not going anywhere.

Absolutely. this bad boy needs to breathe.

I don't run at high speed in a barrel anymore. I used to try to do that before i learned how horrible it is.

 

[flyingscott]

did you replace the flywheel?

 

[jitterbug127]

did you replace the flywheel?

Yes I did! I put the old style 1 magnet magneto on instead of the 2 magnet one that comes on the low tension magneto.

 

[flyingscott]

what happens when you pump the primer ball?

 

[jitterbug127]

what happens when you pump the primer ball?

same thing. It sputters out and dies. I will try one more fuel pump for good measure.

 

[saltchuckmatt]

What you say is true the fuel pump is not going to help. Pretty sure you just tried too many things on this motor instead of focusing on what was really wrong.

 

[jitterbug127]

What you say is true the fuel pump is not going to help. Pretty sure you just tried too many things on this motor instead of focusing on what was really wrong.

Very good and practical advice. Problem i've got is im not sure whats really wrong at this point. I've addressed compression, spark and fuel. Let me post a video. I'm sure it will be more helpful that my pecking on this keyboard.

 

[jitterbug127]

Solved this one yesterday. I took a break from it and have been fishing the last week or so. Low speed idle knob wasn't set properly. I reset it and it runs really well. I've pulled the leg. It will get a new impeller and be ready for the water.