Logo
FULL SITE MENU

43 liter merc sputtering problems

R

ryan_cannon

New member
"Hey everyone....im only 15, b

"Hey everyone....im only 15, but really have gotten a jump into the mechanical world a long time ago, so i do understand alot of things about engines, but there still alot that i dont know so if you could just bear with me.
My 19 footer which has a 2003 4.3 liter merc is having a very bad sputtering problem when i go to turn it off after alot of use, my step dad and i have come to the conclusion that it is a pre-ignition problem, so we brought it into his mechanic, and we timed the engine dead on. But for some reason it wont stop, we even tried higher octane gas. I read up and found it, that it might have something to do with the fuel cutoff solenoid or the idle stop solenoid, but its gonna be awhile before i get around to that project...so im open for any suggestions at what else to do to put this problem to rest. thanks alot everybody

Ryan C"
 
"Ryan
Good on you for having

"Ryan
Good on you for having a go at a young age my friend.
There are plenty of people twice your age that would not have the guts to have a go at it.
If you have a pre ignition problem with your engine there are a couple of things that it can generally be related to, low octane fuel and high engine temps can be a good reciepe for it. High idle speeds when you shut her down with a hot engine can also cause it as well as over advanced ignition timing.
You are already looking in all the right areas, what have you got the idle speed set at and what degree is the timing set to, have you noticed what your engine temp is when you shut it down and get the pre ignition happening.

Cheers
Peter C"
 
"Ryan- do a search here for 4.

"Ryan- do a search here for 4.3L Mercruiser run-on issues. I have posted the details and the technical bulletin number several times and there's a list of things to do, including what Peter mentioned. One of them is to let it idle for about a minute before shutting it down, so it can cool a bit."
 
"The engine temp is fairly nor

"The engine temp is fairly normal, but I pretty much always run it WOT wenever i get the chance, so fairly normal for me could be a little on the high side, so i think not letting it idle down as much as i could is playing a big role in it. Also i did some looking around on other sites, and found out that my idle speed adjustment is located on my idle stop solenoid, so if it was set to idle to high, when i turn off the ignition the solenoid is probaly retracting, but is set to high to let the carb intake close all of the way. Any says on this peter or jim? By the way jim thank you for pointing me to those other boards, alot of the other information i gathered was great.
Thanks alot everybody!
-Ryan C"
 
"If you have an actual idle st

"If you have an actual idle stop solenoid, Mercruiser installed that as part of their fix, since it was an accessory before. If your idle speed is higher than 600-650, get it down a bit lower. The solenoid is for exactly what you say- it's supposed to close the throttle plat completely. If the carb is set too rich, the unburned gas can cause it to run-on."
 
"I think thats my problem(

"I think thats my problem(high idle speeds)because my normal idle speed is around 1000 to maybe 1200
ryan c

p.s what year did they add idle stop solenoids, because my year is 2003?"
 
"ryan;
While at idle, try dis

"ryan;
While at idle, try disconnecting the idle solenoid and see what the idle speed drops to. Like Jim says, you want about 600 RPM max. If there is no drop, the solenoid is not working for some reason, and 1000 RPM is too fast for idle speed.
Rod"
 
Back
Top