Johnson 25EL75B HELP!

dew2

Senior Chief Petty Officer
Joined
May 6, 2010
Messages
674
I am lost with this motor!! Need some advice!
Motor has new coils,plugs,points, condensers,Fuel pump,Carb kit, Starts fine, the carb setting at 1 1/2 turns open gives the lean sneeze it stops at 3 turns open (the sneeze).I cant get it to idle to do fine adjustments,I get it down in RPMs and the throttle seems to have a mind of its own,It revs and slows with just a touch of the tiller twist throttle.I have checked the sync its in range of aligning with the mark when carb linkage moves.Timing light aligns with first mark on the right,Spark test shows great spark.I am running in a barrel, motor submerged 6 inches above impeller,compression at 93 and 96
I get it running easily (starting) higher revs no problem,when I slow down the revs, it responds and slows but then it just dies,its either higher revs or at slow it seems as though it will run at idle but dies.when I turn the throttle down near idle but yet higher RPMs the motor has its own mind it revs fairly high and with just putting my hand on the twist grip suddenly drops in RPMs and dies.ANY and all advice wanted and needed!!
 

Monte1961

Lieutenant Junior Grade
Joined
May 8, 2011
Messages
1,180
Re: Johnson 25EL75B HELP!

I would check for air/vacuum leaks on,in and around carb! You can test this by spraying WD/40 or mixed fuel. good luck!
 

Cofe

Lieutenant Commander
Joined
Apr 23, 2009
Messages
1,883
Re: Johnson 25EL75B HELP!

Try pumping on the bulb, sometimes a weak fuel pump diaphragm won't work at low rpms.
 

AlTn

Commander
Joined
Mar 9, 2010
Messages
2,813
Re: Johnson 25EL75B HELP!

a clear fuel line from pump outlet to carb will help in determining air leaks in the fuel system..you should not have air bubbles present in this line with motor running
 

ultra353

Petty Officer 1st Class
Joined
Jun 21, 2009
Messages
388
Re: Johnson 25EL75B HELP!

Also when sraying the wd-40 around the carb, spray the crankcase halves to check for air leaks.
 

dew2

Senior Chief Petty Officer
Joined
May 6, 2010
Messages
674
Re: Johnson 25EL75B HELP!

Sure appreciate the advice!! But when spraying WD-40 just what am I looking for? I got new fuel line clear and no bubbles in fuel supply,I sprayed wd all over but dont seem to see anything the reason for the question what do I look for when spraying WD-40??
 

ultra353

Petty Officer 1st Class
Joined
Jun 21, 2009
Messages
388
Re: Johnson 25EL75B HELP!

When spraying the wd-40 your listening for a change in rpms, which is an air leak comming from the specific area your spraying at.
 

AlTn

Commander
Joined
Mar 9, 2010
Messages
2,813
Re: Johnson 25EL75B HELP!

how much slop is there in the idle adjust screw at the end of the tiller handle?..also...marineengine.com..cyl. and crankcase..part no. 41..is it sheared or really loose?
 
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