1999 75hp choking out at low throttle

[milehighboater]

I have a 1999 75hp 3 cyl 2 stroke (one that was built by merc) that doesn?t like to idle around in gear that much. I can leave in running at idle in neutral for hours but when it is in gear ie. when I am in a no wake or trolling it will bog down and die. It will run for about two minuites in gear before it bogs down and I can bring it back momentarily if I hit the key in to choke it but if I don't throttle up it will die. The bulb goes soft but never flat and the motor will start up without much problem with a bit of throttle. I have recently replaced the fuel filter, coupling and bulb. It is on a tracker 175 with a permanent tank so there is no fitting there, and the tank has a breather line going to the fuel fill that doesn't appear to be blocked by anything either way there is no change when I run it with the gas cap off (I was checking for a vacuum). The last thing I was going to replace was the fuel pump diaphragm but wanted to see if I missed anything. I brought the boat up from Missouri about 6 years ago had it re-jetted and I don't think the guy did a very good job tuning the idle mixture, any good procedures for that? I think the carbs are good and clean, there is no leaks I can see and I have winterized/decarbed it about once a year. After it gets above about 2000 RPM she runs like a champ, like I said earlier it will start quick and idle in neutral for hours. Anyone that would like to throw around some ideas would be much appreciated. Thanks.

 

[foodfisher]

Re: 1999 75hp choking out at low throttle

Spark plugs. Clean and right ones?

 

[milehighboater]

Re: 1999 75hp choking out at low throttle

Spark plugs are brand new NGK. And the right ones, they are the surface gap type.

 

[foodfisher]

Re: 1999 75hp choking out at low throttle

Proper timing?

 

[Lone Duck]

Re: 1999 75hp choking out at low throttle

What is your RPM at idle ? should be around 5 to 800 in gear.

 

[milehighboater]

Re: 1999 75hp choking out at low throttle

Timing hasn't ever been touched from the factory. and idle rpm is around 800 when it is in gear and just below 1000 in neutral.

 

[foodfisher]

Re: 1999 75hp choking out at low throttle

Are you sure it's loading up and not leaning out? Might be the fuel pump rebuild you're going to do will solve it. Please post results.

 

[milehighboater]

Re: 1999 75hp choking out at low throttle

I think I will go ahead and do the fuel pump rebuild does anyone have any "heads up" for the rebuilds? I know most of the kits are just a diaphram and some gaskets. Does anyone have the idle mixture settings for this motor? And I'm not sure if it is choking out or leaning out is there a way to find out?

 

[foodfisher]

Re: 1999 75hp choking out at low throttle

Don't know the specifics of your motor. Maybe Frank will chime in. Don't know how he handles PM's

 

[milehighboater]

Re: 1999 75hp choking out at low throttle

I just got the new fuel pump from Iboats and it is a Serria, no instructions though. Any tips would be helpful there is a few little parts in this kit I can only guess they are the check valves. I will be doing the work on Saturday and I will try to get it on the water by Sunday and will let everyone know how it goes.

 

[milehighboater]

Re: 1999 75hp choking out at low throttle

Just want to update, I got the pump done just fine and went ahead and did some PM too. I changed the impeller, gear oil, and decarbed the motor and carbs with seafoam. I didn't realize Sunday was easter though and my wife wasn't too happy when I brought up the lake when my in-laws were getting there in 2 hours. I should be able to get out this week, I will post my results.

 

[milehighboater]

Re: 1999 75hp choking out at low throttle

The pump did it. I got it out on the water this morning and it performed fantasticly. I idled around for about 20 minuites without a problem when before 2-3 minuites caused issues. The pump worked well but I had some issues with the check valve stems they sent . The center post didn't want to lock into place so I ended up using the orignals and it worked out okay. I would suggest getting the merc part though. They come with directions and if all the parts fit the first time it is worth the extra 10 dollars or so. Thanks for all the help.