1975 Johnson 25 HP Not Running

[saltchuckmatt]

I tried to use a spray bottle earlier today through the carb to try and keep it running, however it was not successful. I got curious and pulled the plugs and they were not wet at all. I have also rebuilt the fuel pump since I got the engine. I disconnected the hose from the carb and when I pull on the engine fuel comes out of the hose.

I see.....I re-read the thread and it said you cleaned the carb, try rebuilding the carb. You might not have cleared everything as well.

 

[z.fields27]

I see.....I re-read the thread and it said you cleaned the carb, try rebuilding the carb. You might not have cleared everything as well.

My mistake, I forgot to mention that I have rebuilt the carb using a sierra marine kit. The whole thing doesn’t make much sense to me. I have done about everything I know to do and have hit a stopping point.

 

[Crosbyman]

so the pump works . sorry to ask can you confirm fuel enters the carb. ?

to check open the bottom bolt to see if fuel drips out. if none then the inlet needles/float is not working properly. float adjusted level with carb bodey and on the right side ??

did you do a blow test on the carb

air in right side up
no air goes in if upside down.

check the vacum pull on the carb... hold a piece of paper in front of the carb while cranking.. does it pull the paper shut on the carb face ??

did you check the idle channel and drip chamber incl. the side channel. did you blow carb cleaner in the upgoing side channel and see carb cleaner exit the small carb drip holes?

did you install the proper gasket with the side hole lined up with the idle channel ?

did you check the needle tip on the top needle. (should be fine & pointy)
did you try to unscrew the needle half a turn to allow more fuel to be extracted by crankcase vacum ??

 

[racerone]

You put in 6-1/2 drops ( bit of humour ) to quickly determine where the issue is with a motor.----If motor fires it proves spark at the right time and compression.-----So the issue on this motor is fuel delivery.-----Maybe the high speed jet in the carburetor bowl is plugged.----Or maybe the NLA choke detent is broken and choke is NOT FULLY ON during starting effort.----The trouble shooting should not take more than 15 minutes to determine where the issue is.----Fixing it may may take longer depending on many factors !!

 

[Crosbyman]

got gasket #40 in place also ? if not . crankcase vacum could be sucking air instead of fuel
anything further would be beyond my limited skills.

 

[z.fields27]

so the pump works . sorry to ask can you confirm fuel enters the carb. ?

to check open the bottom bolt to see if fuel drips out. if none then the inlet needles/float is not working properly. float adjusted level with carb bodey and on the right side ??

did you do a blow test on the carb

air in right side up
no air goes in if upside down.

check the vacum pull on the carb... hold a piece of paper in front of the carb while cranking.. does it pull the paper shut on the carb face ??

did you check the idle channel and drip chamber incl. the side channel. did you blow carb cleaner in the upgoing side channel and see carb cleaner exit the small carb drip holes?

did you install the proper gasket with the side hole lined up with the idle channel ?

did you check the needle tip on the top needle. (should be fine & pointy)
did you try to unscrew the needle half a turn to allow more fuel to be extracted by crankcase vacum ??
View attachment 392375

Fuel indeed fills the carb up. The float is adjusted level with the body. Vacuum pull was my next test, the plugs are not wet at all despite all of the cranking. In fact the reed valves were not wet at all. Maybe they aren’t pulling vacuum correctly. The correct gasket is in place and the carb was clean how you mentioned. I did unscrew to a turn and a half.

 

[z.fields27]

got gasket #40 in place also ? if not . crankcase vacum could be sucking air instead of fuel
anything further would be beyond my limited skills.

Yes it is in place. I am going to check crankcase vacuum today.

 

[z.fields27]

You put in 6-1/2 drops ( bit of humour ) to quickly determine where the issue is with a motor.----If motor fires it proves spark at the right time and compression.-----So the issue on this motor is fuel delivery.-----Maybe the high speed jet in the carburetor bowl is plugged.----Or maybe the NLA choke detent is broken and choke is NOT FULLY ON during starting effort.----The trouble shooting should not take more than 15 minutes to determine where the issue is.----Fixing it may may take longer depending on many factors !!

I dont believe that the engine is pulling any vacuum at all, so I an going to troubleshoot that today.

 

[racerone]

Be hard for both crankcases to fail at the same time.------Is the choke detent in good shape and working properly , yes or no ?----It is item #21 in the parts diagram.

 

[saltchuckmatt]

Fuel indeed fills the carb up. The float is adjusted level with the body. Vacuum pull was my next test, the plugs are not wet at all despite all of the cranking. In fact the reed valves were not wet at all. Maybe they aren’t pulling vacuum correctly. The correct gasket is in place and the carb was clean how you mentioned. I did unscrew to a turn and a half.

I assume you tried screwing it out more correct?

 

[z.fields27]

I assume you tried screwing it out more correct?

I did try that

 

[z.fields27]

Be hard for both crankcases to fail at the same time.------Is the choke detent in good shape and working properly , yes or no ?----It is item #21 in the parts diagram.

I will have to go check that. What exactly does that do?

 

[racerone]

It ( item #21) holds the choke during the starting process.----Makes sure that the flapper is closed completely and stays closed !----In my opinion this should be an easy fix to get this motor running.----But you never know what the 3 previous owners did to this motor !

 

[z.fields27]

So after today I feel like I havent gotten anywhere. I already had the reed valves off so I checked the vacuum on them, all was good. Put the carb back on, same with it. Tried and tried to start it with no luck at all. I pulled the flywheel to check points again and realized that the flywheel was a little loose. I also realized that the bushing that holds the key and the flywheel has a crack. What would those cracks do? Could it stop the engine from running? I put the flywheel back on to torque spec and pulled on it. To my surprise it started and I quickly shut it off to get it in some water. I got it in some water and it began to start but didn’t have enough to start. It also began backfiring horribly at this point. At this point I am not sure what to check for or try.

 

[z.fields27]

It ( item #21) holds the choke during the starting process.----Makes sure that the flapper is closed completely and stays closed !

It was not working the way intended and I have known this but I have figured out a way to hold the flapper shut completely.

 

[racerone]

Hurry to a boat repair shop if you can find one to work on that simple motor.

 

[z.fields27]

Hurry to a boat repair shop if you can find one to work on that simple motor.

Trying to avoid that since they want $125 an hour just to look at it. Between being laid off and just wanting to learn how to work on things myself I would prefer to keep troubleshooting myself.

 

[saltchuckmatt]

So after today I feel like I havent gotten anywhere. I already had the reed valves off so I checked the vacuum on them, all was good. Put the carb back on, same with it. Tried and tried to start it with no luck at all. I pulled the flywheel to check points again and realized that the flywheel was a little loose. I also realized that the bushing that holds the key and the flywheel has a crack. What would those cracks do? Could it stop the engine from running? I put the flywheel back on to torque spec and pulled on it. To my surprise it started and I quickly shut it off to get it in some water. I got it in some water and it began to start but didn’t have enough to start. It also began backfiring horribly at this point. At this point I am not sure what to check for or try.

Post pictures of cracks....began to start but didn't have enough to start....enough what?

Backfiring is typically timing so your on to something. Make sure your plug wires are on the right plug.

 

[z.fields27]

Post pictures of cracks....began to start but didn't have enough to start....enough what?

Backfiring is typically timing so your on to something. Make sure your plug wires are on the right plug.

I dont have a picture of it right now but will get one posted on here tomorrow. The cam magneto along with the flywheel is what is cracked. It started and just seemed to die out as if the spark gave out, that is the best I know how to explain it. I will double check those again tomorrow but I am almost positive they were on the right one.

 

[z.fields27]