suzuki DT-40 rpm fluctuations

13whaler

Recruit
Joined
Apr 21, 2009
Messages
2
been reading the forums on this common suzuki problem. Its a mid 80's DT-40. Boat runs great at about 2/3 throttle , when you max it out it runs strong for bout 5-10 seconds then the RPM fluctuates drastically until it eventually stalls out...after a few tries will restart and perform about the same. I rebuilt the fuel pump, changed the quick disconnect fuel fitting. I read that a faulty water flow switch on the head could cause this problem, but the suzuki parts guy said that the alarm would sound when the switch fails and the rev limiter gets active. Is that 100% true? Dont want to change the switch($65) and risk breaking bolts if the carb is in need of a rebuild. BTW didnt change fuel filter yet...long shot. Thanks for helping Craig
 

cousinabe

Senior Chief Petty Officer
Joined
Nov 13, 2001
Messages
765
Re: suzuki DT-40 rpm fluctuations

definitely sounds like a fuel restriction.
change that filter and report back.
does pumping the primer ball help during the high speed problems?
 

Mas

Lieutenant Commander
Joined
Oct 3, 2006
Messages
1,656
Re: suzuki DT-40 rpm fluctuations

Gummed up carb...high speed jet?

MAS
 

13whaler

Recruit
Joined
Apr 21, 2009
Messages
2
Re: suzuki DT-40 rpm fluctuations

cousinabe ..i will change the filter and let you know thanks...Mas can the jet be cleaned without disassembeling the carb?
 

Mas

Lieutenant Commander
Joined
Oct 3, 2006
Messages
1,656
Re: suzuki DT-40 rpm fluctuations

Nope, you gotta get into the carb. Do not be affraid, carbs are not as complex as you might initially think.

MAS
 

joeseif

Seaman Apprentice
Joined
Aug 14, 2009
Messages
33
Re: suzuki DT-40 rpm fluctuations

where is the high speed needle and how is it adjusted?
 
Top