2008 - 4 Stroke 50hp Big Foot - Stock Prop - No Longer Can Get Over 5000 rpms

Mdavis

Cadet
Joined
Jun 30, 2009
Messages
17
Hi everyone, I have a 50HP Bigfoot with less then 20 hours on it.

First time I took it out this year I was able to get my normal 6000 rpms, but now I can only get 5000 rpms out of her. Motor sound great/sounds normal, but don?t know why I have lost 1000 rpms. I have made no changes to the boat between the 6k to 5k rpm dip.

One thing I did notice is when I was cruising at about 2,000 rpms the motor made a little higher pitched noise (not a bad sounding noise) and rpms went up a bit then right back down to 2,000 without touching the throttle.

What do I need to check, going out tomorrow and would like to see if I can get this problem solved so I can test.

Thanks in advance everyone!
 

sxmerc

Petty Officer 1st Class
Joined
Jul 13, 2010
Messages
247
Re: 2008 - 4 Stroke 50hp Big Foot - Stock Prop - No Longer Can Get Over 5000 rpms

I don't think your problems are prop related. Sounds like a fuel delivery issue, whether it be a fuel restriction, or an issue with one of the fuel pumps. How old is the fuel, was it treated before you put the boat up?? Have you changed your fuel filters this year? Start here, and post with the results.
 

Jeep Man

Commander
Joined
Oct 17, 2008
Messages
2,803
Re: 2008 - 4 Stroke 50hp Big Foot - Stock Prop - No Longer Can Get Over 5000 rpms

+1 with sx. Replace you fuel filters (there is 2 of them) and check your tank for contaminants.
 

Mdavis

Cadet
Joined
Jun 30, 2009
Messages
17
Re: 2008 - 4 Stroke 50hp Big Foot - Stock Prop - No Longer Can Get Over 5000 rpms

Hi everyone...I would find it hard to be my fuel as it would be sporadic. This acts the same every time and boat runs/sounds perfect at any RPM range.

A couple of things I figured out while taking it out again this week. If I pushed my throttle up very, very slowly...like one minute between idle and full throttle and I was able to get up to 6,000 rpm's! Did this once and couldn?t get it to do it again...back at the 5000 rpm?s. I also notice that when I get to 5000 rpm?s I can push the throttle up about another inch and not get any additional rpm?s out of the motor. Seems that my throttle is very stiff compared to my last boat. Could I have a throttle cable issue? If so what do I look for??

Thanks in advance for everyone?s help!!
 

will941s

Chief Petty Officer
Joined
Oct 1, 2007
Messages
540
Re: 2008 - 4 Stroke 50hp Big Foot - Stock Prop - No Longer Can Get Over 5000 rpms

Far shot, but keep it on the trailer and back it in the water, or have someone drive the boat while you do this. Remove the cover, run to WOT and try to push the arm manually on the motor to see if you can get it to 6,000 RPM's. If you can, then there is a cable issue...maybe just a adjustment. Just what I would do...then again half the crap I do is'nt how a shop would do it.
 

Mdavis

Cadet
Joined
Jun 30, 2009
Messages
17
Re: 2008 - 4 Stroke 50hp Big Foot - Stock Prop - No Longer Can Get Over 5000 rpms

Ha!! Even better yet..... would I need to go to the lake?

Could I not just go out in the shop, push throttle as far forward as possible, open the motor up, and see if I can manually push the throttle cable even more? Would that work?

I figure if can manually move it forward more I need to do some cable/linkage adjustment.
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,589
Re: 2008 - 4 Stroke 50hp Big Foot - Stock Prop - No Longer Can Get Over 5000 rpms

Could be a linkage problem. Is this on a pontoon? Has it set in water over the winter?
 

Mdavis

Cadet
Joined
Jun 30, 2009
Messages
17
Re: 2008 - 4 Stroke 50hp Big Foot - Stock Prop - No Longer Can Get Over 5000 rpms

Could be a linkage problem. Is this on a pontoon? Has it set in water over the winter?

Yes, this is a pontoon but in a heated garage at all times.
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: 2008 - 4 Stroke 50hp Big Foot - Stock Prop - No Longer Can Get Over 5000 rpms

How much 'old' fuel is still in the tank from last year?

Can you rig a small portable tank of 'fresh' fuel to test?
 

Mdavis

Cadet
Joined
Jun 30, 2009
Messages
17
Re: 2008 - 4 Stroke 50hp Big Foot - Stock Prop - No Longer Can Get Over 5000 rpms

How much 'old' fuel is still in the tank from last year?

Can you rig a small portable tank of 'fresh' fuel to test?

Not a "old fuel" issue. Have already looked into this. :)
 

phillipians 2:8

Recruit
Joined
Apr 12, 2011
Messages
5
Re: 2008 - 4 Stroke 50hp Big Foot - Stock Prop - No Longer Can Get Over 5000 rpms

hey bud, i am having an identical problem with my tracker only difference is mine is a 20 hp. i got mine to get up to 5800 once and according to my speedo it said 20 mph. ispent another hour and could not get to repeat. but what i did was kept adjusting trim. maybe you need to play with the trim. i have power tilt but not trim so once i get over 2000 rpm icant raise the motor but, i can lower it so i would start out with the trim out and keep bumpin down till i got max rpms. but i couldnt get it to do it again. maybe this will help. i hope
 

Mdavis

Cadet
Joined
Jun 30, 2009
Messages
17
Re: 2008 - 4 Stroke 50hp Big Foot - Stock Prop - No Longer Can Get Over 5000 rpms

hey bud, i am having an identical problem with my tracker only difference is mine is a 20 hp. i got mine to get up to 5800 once and according to my speedo it said 20 mph. ispent another hour and could not get to repeat. but what i did was kept adjusting trim. maybe you need to play with the trim. i have power tilt but not trim so once i get over 2000 rpm icant raise the motor but, i can lower it so i would start out with the trim out and keep bumpin down till i got max rpms. but i couldnt get it to do it again. maybe this will help. i hope

Understand what you are saying, but this is not it either. I can trim at anytime and at any Rpm range. I also understand how to get the most Rpm's out of a motor. Thanks for the input though.......will open her up and look at the linkage tonight.
 

Mdavis

Cadet
Joined
Jun 30, 2009
Messages
17
Re: 2008 - 4 Stroke 50hp Big Foot - Stock Prop - No Longer Can Get Over 5000 rpms

Ok everyone, I figured it out. Was the throttle set screw back under the casing. Lessened it up, which allowed the throttle to be engaged more and in return...back up to 6,000 RPM's.

Thanks everyone!!
 
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