Mercury 4 stroke altitude problems?

MPMerc

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Joined
Sep 6, 2009
Messages
5
I just bought a new Mercury 4 stroke 5HP from a boat dealership in Salt Lake City. I took it up to a reservoir nearby a couple of days later to do the break in and to troll for the rest of the day. The motor was hard to start but I got it running and did the half and 3/4 throttle as the manufacture tag had instructed to do. After that, we trolled for about 5 hours with little problems. before the end of the day, it choked out and I changed the plug and ran it at half throttle a little more before I got off the lake. I took it back to the dealership and they ran it for 4-5 hours in their tank with no problems at low idle-this is where I need the motor to run to push a 16 foot smokercraft at slow trolling speeds.
I put the trolling motor back on this last Saturday and went back up to the same reservoir-(Strawberry) and couldn't get the motor to run for more than a few minutes at a time without stalling out again. If I took the remote fuel supply off of the motor, it would seem to run for a while but the second I put it back on it would flood again. I called the dealership from the lake to see if they had any suggestions and was asked to check the primer bulb, vent, and other things with no resolution. They said it was probably the remote tank which is new-and to bring it back on Tuesday to check it out again. I brought the boat home and thought I would try one more time to see if the motor would run. I put it in a clean plastic can, filled it with water and the motor fired right up. After I ran it for a few minutes at various speeds, I flipped the forward switch and turned the tiller down to the lowest spot and let the idle run almost 2 hours with no problem whatsoever.

I live at 4300 feet and Strawberry, Flaming Gorge, and the other areas I intend to fish are over 6000 feet above sea level. Strawberry is 7600 feet. What are my options here? I just bought this motor and shelled out the cash for a 4 stroke so I wouldn't have any problems and sold my 2 stroke. I am very frustrated with this situation-if anyone can steer me to a good mechanic in SLC, or give me any ideas or options-I would greatly appreciate it.

Sorry for the long post.
Thanks,
Mike
 

sschefer

Rear Admiral
Joined
Nov 13, 2008
Messages
4,530
Re: Mercury 4 stroke altitude problems?

Well, shoulda coulda woulda, the 9.9 is the best engine for you. Take this one back and get the Tohatsu 9.9 and save some major bucks. They are both nearly identical and both made by Tohatsu. You didn't buy a Merc you bought Merc decals and controls.

If you really want control get a 65 lb 24v Minkota puller with auto pilot and remote control. I put one on my 18 and with two group 27 batteries I can troll at 1.75mph for 8 hours. 6 hours if I kick it up to 2.5 when trolling with needle fish and such.

The nicest thing about it is it's dead quiet and you gotta love that. I'm serious, I was going to go with a kicker but after using this thing I'll never bother with a kicker again. I have a honda 2000 generator that I leave running on the boat at night if I leave it in a slip. The weight is about the same too.
 

MPMerc

Recruit
Joined
Sep 6, 2009
Messages
5
Re: Mercury 4 stroke altitude problems?

So what your sayng is I should just try to get the best deal on my 1500.00 and not try to solve the problem. I already have a 50 lb thrust Minn Kota maxum mounted on the bow. I bought the trolling motor to be able to run all the time if I have gas in the main tank or the remote tank. I have a 75 horse Optimax that gets me round from place to place in a few minutes.

Surely Mercury doesn't sell these motors just to have customers have a bad experience with a new motor and just bag it. I appreciate your comments but I will call Mercury tomorrow to see what they recommend. Why offer any motor to a customer above 6000 feet and tell them their SOL if it doesn't work-I have a hard time believing that. Surely there is somone on this forum who has had the same problem....

-MP
 

sschefer

Rear Admiral
Joined
Nov 13, 2008
Messages
4,530
Re: Mercury 4 stroke altitude problems?

Agree with all you say, what you have to remember is that these engines are designed to run at sea level unless you order it as a high altitude engine and some do not have that option. The 9.9 Merc Kicker is a special version that is setup to be a kicker. I've seen those run great at sea level one day and great at 5200 feet the next.
 
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