Surging Johnson 6 hp.

[Crosbyman]

Bummer I guess ....



suggestion... up to you .....but if your 4hp works fine transfer the magneto parts to the 6hp. if surging stops you found the area of concern.

if surging does not stop...fuel starvation is occuring..... back to fuel , carb, hose tank issues.
Try the engine with the cowl off in case (rare) you have exhaust fumes leaks killing the carb fresh air supply .


you did check compression and check temperatures. ?

 

[jitterbug127]

Bummer I guess ....



suggestion... up to you .....but if your 4hp works fine transfer the magneto parts to the 6hp. if surging stops you found the area of concern.

if surging does not stop...fuel starvation is occuring..... back to fuel , carb, hose tank issues.
Try the engine with the cowl off in case (rare) you have exhaust fumes leaks killing the carb fresh air supply .


you did check compression and check temperatures. ?

Compression check was 90/90 so it’s good.

I’ve not checked the temperatures, but I’ve got a thermometer I think would work.

I will swap the magneto components to give them a try. Both these motors are 1976 so I think should line up well. This 6 hp is a gorgeous Johnson motor so I’m pretty excited to fully restore it. I’m ordering a new recoil part of it as well.

 

[airshot]

Try some fresh fuel and be spot on with the oil mix. Often bad fuel comes directly from the station where you bought it. Do I recall you doing a spark gap test ??

 

[jitterbug127]

Try some fresh fuel and be spot on with the oil mix. Often bad fuel comes directly from the station where you bought it. Do I recall you doing a spark gap test ??

I haven’t done a spark gap test in a while but I’m thinking it jumped a 1/4” gap no problem. Will check and try again.

 

[jitterbug127]

Fresh fuel no improvement.

I think I can diagnose or at least describe a second symptom.

At idle shell sputter our and die
At high speed shell run strong and just die. I was hoping fuel pump but 2 fuel pumps run strong on my 4 horse power

 

[Crosbyman]

pump is ok carb is clean and adjusted .... ignition works.... fuel/oil is fresh... hand pumping does not help

BTW HS jet orifice
"I checked the bottom jet and it looked pretty good." ....looked and clean are not the same.. did you clean it ??

Cylinders need the fuel to work and that comes from pulling it in from the carb on the upstroke then pushing it into the cylinders on the downstroke.

possible problems to be explored ...
does skirting fuel in the carb face help ?
Grey hose collapse syndrome ..
crankcase suction on the carb... can you feel it on the carb face ?
poor crankcase vacum (to suck in the fuel) due to a bad crankcase seal air leak
exhaust output impaired due to heavty carbon build-up.

 

[airshot]

Fresh fuel no improvement.

I think I can diagnose or at least describe a second symptom.

At idle shell sputter our and die
At high speed shell run strong and just die. I was hoping fuel pump but 2 fuel pumps run strong on my 4 horse power

Even though fuel is fresh, test it !! Often folks are buying fuel that has water in it without knowing. Many stations do not perform proper maintenence and change their filters, they just sell gas !!

 

[saltchuckmatt]

Motor could just be wore out. At 90 90 if they run bad I turn them into parts motors or rebuild them.

2 things to note...
"Running in a barrel at full throttle" ? (Not advisable) "flow problem " (might still have an issue? IR gun with multiple shots while running on a boat)

Spit balling here really.

Congrats for being persistent.

 

[Crosbyman]

"Patience brings joy"

chasing to many rabits.. let it sleep for a week or few days start over with a fresh methodical approach

 

[jitterbug127]

Y’all have been great as always! I have only done the following few things to check out this motor this time around

1. Cleaned the entire carb again including the bowl high speed orifice.
2. Bought new fuel and mixed it properly at 50:1. (I didn’t test it honestly never have even thought of doing it).
3. swapped the fuel pump I had on the 6 with the one I had on the 4 hp. The 4 hp ran good with either fuel pump on it.

 

[jitterbug127]

I’m am not good at technology but here is a video. I moved the motor to my big barrel after this but the video didn’t save for whatever reason

 

[saltchuckmatt]

Video is fine....I transfer my videos to YouTube and send the link.. easier for people to see.

You have no choke knob....is the choke staying open?

 

[jitterbug127]

Choke is working just fine. I cleaned the carb and haven’t put the knob back yet. I was just doing it by hand Incase I had to take choke back off.

 

[oldboat1]

Tank vent? Also, it looks like you need more water in your barrel -- run it about half way up the shaft. When right, there should not be any water thrown from the prop, only spray from the discharge ports under the powerhead, or from the tell-tale outlet (if provided). Run it as slow as it will idle without coughing or stalling (adjust accordingly). Higher speed operation is tested and adjusted when running in the lake.

 

[Crosbyman]

your running much to fast ...water will aerate in the bucket and be hard to get pumped to cool the engine. no need to run that fast

in my humble opinion it is just running out of fuel ...carbs have 2 circuits LS HS run at low speed to see it if "fuels out"

if not..... the HS circuit is messeg up . sorry to say

recheck HS orifice HS throttle post side holes if any
do a visual on all path.

check to see that the air vent is working on the carb (small hole in front to balance ambiant air pressure )

recheck the screen on the pump

 

[jitterbug127]

Tank vent? Also, it looks like you need more water in your barrel -- run it about half way up the shaft. When right, there should not be any water thrown from the prop, only spray from the discharge ports under the powerhead, or from the tell-tale outlet (if provided). Run it as slow as it will idle without coughing or stalling (adjust accordingly). Higher speed operation is tested and adjusted when running in the lake.

Tank Vent was open all the way. Thank you for the update on the barrel. I have a 55 gallon barrel I got out of the backyard to run the motor in. I am testing in that barrel now. She wants to sputter out and die at idle.

 

[jitterbug127]

your running much to fast ...water will aerate in the bucket and be hard to get pumped to cool the engine. no need to run that fast

in my humble opinion it is just running out of fuel ...carbs have 2 circuits LS HS run at low speed to see it if "fuels out"

if not..... the HS circuit is messeg up . sorry to say

recheck HS orifice HS throttle post side holes if any
do a visual on all path.

check to see that the air vent is working on the carb (small hole in front to balance ambiant air pressure )

recheck the screen on the pump

I will check all of this! Thank you!

 

[Crosbyman]

I will check all of this! Thank you!

did you actually remove the main hs post of the HS circuit by unscrewing it and flushing it incl the small side holes if any on your model ?

careful if you unscrew it use proper fitting flat blade don't strip it .

On some carbs the HS speed post side hole help to vaporize the fuel sucked from the carb see this old model ..yours has no HS needle or carb glass bowl but they are all the same basic carb

here is one more test...


forget the square fuel pump... hook up a small container with fuel and gravity feed fuel into the carb inlet see what that does ???

check the rear alingment of the crankcase pulse port behind the pump gasket to ensure proper operation of the pump.

 

[oldboat1]

Tank Vent was open all the way. Thank you for the update on the barrel. I have a 55 gallon barrel I got out of the backyard to run the motor in. I am testing in that barrel now. She wants to sputter out and die at idle.

Try adjusting the slow speed needle counter-clockwise 1/8 turn. Repeat if still stalling (richer adjustment -- more fuel).

 

[jitterbug127]

did you actually remove the main hs post of the HS circuit by unscrewing it and flushing it incl the small side holes if any on your model ?

careful if you unscrew it use proper fitting flat blade don't strip it .

On some carbs the HS speed post side hole help to vaporize the fuel sucked from the carb see this old model ..yours has no HS needle or carb glass bowl but they are all the same basic carb

I did unscrew and clean the high speed post. It has 3 tiny holes that are all completely cleared out. The high speed post and that high speed orifice are both completely cleaned out and look perfect.