58 johnson 18 horse, starts great but dies after 30 seconds. Great prime.

[dwittig33]

Starts right up and runs and sounds great for like 30 seconds. i thought the problem was my tank, went and bought new gaskets and now have excellent prime, however it did not fix the problem. I have great compression at 100, great spark and am at a loss. The carburetors are so simple on those, but i'm thinking it has to be that problem.

i was looking at the carb, and couldn't figure out what is supposed to go into those threaded holes in the middle of the picture (bottom left side of the carb bowl). i pulled up a parts diagram but it didn't help. Any ideas? Thank you.

 

[dwittig33]

another picture for scale. thank you

 

[HighTrim]

Sorry pics are not working. This site has been "Improved" believe it or not!

You will have to use a site like photobucket to post pictures.

Are you running a pressure tank?

 

[dwittig33]

Yes on the pressure tank. Brand new gaskets. I'll work on the pictures

 

[HighTrim]

Does the tank hissss after removing the cap after it was running for 30 secs? Did you replace diaphragm? If you continually pump the primer button will it continue to run?

 

[dwittig33]

Yes it hisses. Diaphragm is brand new. No it does not continue to run if I pump it. The tank and the prime is golden.

 

[HighTrim]

Ok pull carb, clean and rebuild. I wish I could see what you are talking about but cannot see the pics. Not your fault, it is this site.

 

[dwittig33]

for the pictures try these links:

https://mail.google.com/mail/u/0/?u...64242383&rm=147b366ba0ef64fa&zw&sz=w1342-h547

https://mail.google.com/mail/u/0/?u...64242382&rm=147b366ba0ef64fa&zw&sz=w1342-h547

so i have tore apart and cleaned the carb a couple times, but did not make a difference. So i just had an realization that my lower adjustment needle does not have a gasket on it, must have lost it at some point. i have had it adjusted right (at a full turn out) but without that extra space provided by the gasket i'm in there too tight still. You think that could be what is choking my fuel supply after the initial choke burns out?

 

[dwittig33]

also this link will take you to a parts diagram for the carbuerator.

http://www.marineengine.com/parts/j...manufacturer=Johnson&section=Carburetor+Group

that washer that i'm missing is number 62. however that seems to be the only part that they don't have any information on. any chance you know the oem number or anything else about the size of washer i need? thanks.

 

[HighTrim]

Those are fibre washers behind the packing nut. They have a few functions.

Prevent fuel from leaking out
Prevent air from getting in
Keep the needle from vibrating around once set.

You will definitely need those. 1 will not be enough, I put at least 2 in, usually 3 in the high speed.

They are OEM 0307583 or Sierra 18-7106-9 for a 10 pack (better deal)

 

[dwittig33]

thank you. ordered some on amazon. were you able to pull up the pictures of the motor where i think i may be missing something on the carb?

 

[dwittig33]

a better way to see what i'm talking about would be to pull up the parts diagram again and i'm wondering what screws into number 59. Thanks for your help.