Need help/advice/ideas on 1986 Honda BF75 (7.5hp) 4 Stroke motor not starting/running

[tuggeyt]

Hello.... I need some help/advice/suggestions/ideas on my 1986 Honda BF75 (7.5hp) 4 Stroke motor.
Ok so here it goes... Got the motor with a boat few months back. When I got the motor it didn't run
due to carb being dirty. I took the carb apart and cleaned it and got it running within the first week
and it was running pretty good. Had to fix a couple minor things on the boat and well the boat ended up
sitting for a little over a month.

Went to try to start it and it wouldn't so figured carb again.
Took it apart and cleaned it. Put it back on and when I pumped gas in to it, it would **** out everywhere.
So figured the float got stuck or some dirt under it somewhere so took it back apart and cleaned it
again and put it back on and it started and was fine. However after about 5 minutes it died and now I
cant get it started again. Cleaned carb 3 additional times. Took out every jet and used a needle and
cleaned every small hole I could find and this still did not work.

I am getting gas, I am getting spark, and compression is good.
Has new plugs/wires, new fuel/fuel lines. I cant figure it out. :mad-new:

 

[Sea Rider]

Gee, that's a 28 year oldie. What's your fuel pump diaphragm condition ? Is it hardened, cracked, balooned, if so, replace. Was tank vent opened when engine dropped dead ?

Happy Boating

 

[tuggeyt]

Yea I know but still kicks like a champ when it runs lol.
And I have not checked the fuel pump diaphragm but I'm sure
it is the original so could be replaced.
And my gas tank doesn't have a vent.
I see where this could kill the engine after running due to the vacuum created.
But my thing now is I cant get it started now.
didn't get to play with it much started raining but got a minute to give it a couple
pulls and get nothing.

 

[Sea Rider]

E fuels are very mean to thin rubber diaphragms compared to non E fuels. If engine produces a good visible spark you already have solved 50% of any troubleshooting procedure. After 28 years using original diaphragm, likely your fuel pump diaphragm is already kaput, nothing is eternal, diaphragms much less. Don't lose precious boating time wild guessing. Personally no way going boating with a 28 year old fuel pump diaphragm. Aircrafts and boats have special considerations compared to cars...

Happy Boating

 

[tuggeyt]

Would the diaphragm cause it not to start? The carb still gets gas.
I got a couple hours of sun before rain hits today hopefully so I am
going to go play with it. Ill double check the spark and everything else.

 

[tuggeyt]

Well got it to start.... took the plugs out and cleaned them, filled and emptied fuel in it a couple times.
Got it started and it ran for about 30+ minutes... stopped it and took a lunch break lol.... came back and it wouldn't start again.
So did the same thing over... started again after about 10 pulls.... ran it for about 20 minutes and shut it off...
gave it about 5 minutes tried to start again and again a pain to start at about 6-10 pulls... this time is started ran
for about 10 seconds then the carb started to spit gas out :facepalm: :mad-new: sooo emptied the gas from it. blew in some of the lines.
etc... started it again and it spitted out gas again.... Stopped for the day and will return to it within the next couple days when I'm off work.

New question... Once I started it first and second time... Oil spewed from a drain line or something?
only upon start then stopped... Also if I put it in gear and revved up the engine for a second it did it again a little...
Is this suppose to happen? a purge or something? Also oil had a smell of gas in it too....

 

[Sea Rider]

How's carb's needle tip and valve seat condition ? Tip must be evenly pointy, if not it's not closing properly against seat, will make starting diffficult and even flood the engine.. When attempting to start after several cord pulls, if you remove plugs, are they wet ?

Happy Boating

 

[tuggeyt]

From what I could tell when I cleaned the carb they looked fine to me.. I think some debris is stopping it from closing so
when I play with it again I will take the carb apart and clean it and check them again to make sure...
Also sometimes they are wet and sometimes they are not?? I remember when I couldn't get it started at first I took them out and
they looked wet.... but the second time it wouldn't start I took them out they looked fine...
and the third time I couldn't get it started the top plug was clean but the bottom plug was wet..