2003 mercury 150 saltwater issue>>>help!

[djelies]

I currently own two 2003 mercury 150hp saltwater series (carb'd) outboards. Both with about 190 hours on them. One of the engines has been giving me problems idling on the initial start-up, once its been run for awhile it behaves, but this weekend i decided to turn it up and i got on em pretty good for awhile just to see how much rpm they can turn, and it ran fine. stopped the boat, then when i went to take off again that same engine was shaking and surging like crazy! i took it easy for awhile cruising at 2000rpm then all of a sudden it picked up speed and rpm's by itself and was running fine. i took her back out and noticed everytime i hit 2800-3200rpm it does the same thing kinda like a misfire/surge and the boat gets to vibrating alittle. get past that 3200rpm mark and she runs good again, i did that several times and it still did it. boats 2 hours away so im taking any and all suggestions before i go back to work on it! thanks

 

[ufm82]

Re: 2003 mercury 150 saltwater issue>>>help!

Sounds like a simple carb issues- crud in the bowl, etc. Have the carbs been cleaned in their 7 years of life? Do you run the boat fruquently or just occasionally and do you have a fuel/water separator like a Racor on the boat? Twins typically are set up with such but who knows.
Carb cleaning will most likely fix you but with the 2 hour commute it can be daunting to mess with. Do you do your own work or do you rely on a mechanic?

UFM82

 

[djelies]

Re: 2003 mercury 150 saltwater issue>>>help!

I have been a mechanic for john deere for 15 yrs, and did automotive before that. i know my way around my tool box, but have never even seen an outboard till a month ago when i bought this boat. that being said i dont think these engines got alot of use considering the original owner bought a yacht two years ago. and the low hours on them for being 2003 motors. it does have racor with water separators, i have been running it every weekend since i bought it in june (went through 110 gallons of fuel in less than a month). good sugestion on the carbs though, trying to get all recommendations before taking the trip to go diag it. thanks

 

[snookfisher]

Re: 2003 mercury 150 saltwater issue>>>help!

I agree with ufm82 - just had a similar issue with mine once and it was all connected to gas issues (gum in the injectors (carbs for you) after it had been set up too long). If you have not done so already, go to ethanol free gas, use some Seafoam and Ringfree and try to tun it out some.

Ethanol is a killer to O/B motors - especialy carb versions.