Slight hesitation ! ? 3.0ltr merc

[Welsh Rob]

Hi Again from the UK,<br /><br />I have just returned from a short fishing trip in my pride and joy............Rio 600 fisher,<br /><br />Running a Yr 2000 3ltr mercruiser 135hp alpha drive.<br /><br />All seems really good exept a simmilar prob to many threads I have read so far on this forum,and that is the 3ltr lump is quite a lumpy unit on 600 rpm tickover!!<br /><br />My concern however is......... when i depart the marina and increase the revs I get a very slight hesitation as if shes going to die but then she picks up just fine!!??<br /><br />I use unleaded fuel but not sure of the octane rating! (could this cause it)?<br /><br />Any suggestions appreciated gents,<br />Many thanks<br />Rob<br /><br />PS AWESOME SITE THIS!

 

[chrisg]

Re: Slight hesitation ! ? 3.0ltr merc

Welcome for over teh big pond!<br /><br />I have the same issue with my 3L 4 banger. I noticed that if I accelerate slowly at first and get up to speed, it is fine from then on.<br /><br />I my case, it only happens when the engine is cold. Once I have run it once, it is fine. I actually had my die if I 'gun it' immediatly. I just run the boat once befor trying to pull anyone up on skies.<br /><br />Perhaps other can explain what is happening. <br /><br />good luck!

 

[SeaSkwurrel]

Re: Slight hesitation ! ? 3.0ltr merc

Sounds like accelerator pump or passageway issues. Have you rebuilt the carb recently?

 

[chrisg]

Re: Slight hesitation ! ? 3.0ltr merc

Perhaps Don Can provide some insight into this. Someone told me that the Merc appears to be cold blooded.<br /><br />I asked others with I/Os and they say its the same for them. They also say it is not only engines, lots of people act the same way. Are you able to get up and go full out first thing when you get up in the morning? Most people ( and this engine) have to start-up gradually before they are off and running. (Coffee helps)

 

[Welsh Rob]

Re: Slight hesitation ! ? 3.0ltr merc

Thanks to all<br /><br />Think the problem is now sorted<br /><br />Boat had been unused for nearly 8 months,ran the fuel tank real low,refilled with fresh and added a dose of fuel/carb cleaner,ran her round the bay for a couple of hours and behaving fine now!<br /><br />Cheers<br />Rob

 

[QC]

Re: Slight hesitation ! ? 3.0ltr merc

Originally posted by Welsh Rob:<br /> Thanks to all<br />added a dose of fuel/carb cleaner,ran her round the bay for a couple of hours and behaving fine now!

I had a 1984 3.0 OMC 140 (same engine). I had that same problem for the 10 years I owned it. This is very unscientific and flies in the face of something, but what worked for me was a little bottle of ANY cheap fuel treatment. Didn't matter if it was lead replacement or STP fuel treatment, or injector/carb cleaner. With a bottle in the tank, no issue, without, I had the hesitation. Like night and day. If you are pulling skiers, feathering the throttle is just not an option . . .

 

[chrisg]

Re: Slight hesitation ! ? 3.0ltr merc

I Just got some of that sea foam(sp?) stuff, will have to dump the tank and see if it works like you guys say.<br /><br />This site does have some good advice.