[kemhardt]

The previous time i took the boat out was about 2 weeks ago with my gf and our two kids. Boat ran great and had just added smart tabs. So I was trying a new setting (#4) that day and the boat was running better than ever (54mph). I also had basically 3/4 full tank of gas from last winter with stable in it.

I took it out sat. and the boat ran terrible...started fine...idled fine....but when i went to go it just didn't have any umph? Top speed was about 30 and it sounded like the prop was spinning faster than we were going? The sound of the motor was fine expept the throttle was all the way down and we weren't going any faster but the rpms were where they should be.

All the guages read normal as to any other time I had the boat out.

I have a 96 shahbah 180 with a 4.3 alpha 1.

Any ideas? I am really leaning towards the gas but not sure as after my first trip out i had a half tank of the old gas so sat. morning topped the gas off full with new gas. almost wish i would of just ran the old out then put new in.

I'm going to put some sea foam in it.

I did happen to pull the spark arrestor off before the trip and thouroghly clean it...so i know that it is getting air.

Anything i'm overlooking that might just be easy instead of worring for the worst?

Thanks

[mikeyt]

And i'm assuming you have cleaned or replaced the fuel filters?

[kemhardt]

I have not cleaned or replaced the fuel filter but will do when i dump in the sea foam.

[jarwiebe]

Originally Posted by kemhardt

The sound of the motor was fine expept the throttle was all the way down and we weren't going any faster but the rpms were where they should be.
All the guages read normal as to any other time I had the boat out.
Thanks

Are you saying that at 30 mph your RPMs were in the WOT range or were they where they normally would be at 30mph? If they were at WOT then I would guess you don't have a fuel problem but possibly a drive problem, either a spun prop or a coupler problem.

[kemhardt]

i have to admit...the more I try and recall the RPM's I cant' remember what it read except for the fact that it wasn't at an alarming range. I just remember the boat rpms were louder yet i wasn't going faster. All though the boat did plane (might of been the tabs forcing it too) the boat rode horrible in the waves and seemd like I had no contol with my trim button. I even remember trying to idle into the boat slip and it seems like I had lost control of the boat and it was really loose in the back end.

When we anchored down after the first ride around the lake I actually got in the water in the back of the boat to make sure the tabs were still attached. Thats how odd the boat rode and felt.

I am leaning more towards the prop. I am going to take it off in the next few days and inspect.

What size socket does it take for the 4.3L mercruiser?

[ColoradoDiablo]

1 - 1/16" if I remember right. I got one of the floatable prop wrenches and really never paid any attention.

[mikeyt]

R u sure that someone didn't slip a 3.0L in that boat when you weren't looking?

Given you have the same boat as i do, you should hit the mid-high 40's with a 19" 3 blade prop and your rpms should be right around the 4700 mark at WOT.

[kemhardt]

I had the boat out two weeks ago with the kids and the boat rode ubbelievably good and the speedo read 54 mph which is about what it normal is more like 51-52.

So it was very noticable when all I could do was 30ish....heck the thought even crossed my mind I had accidently forgot to pull up the anchor and had been dragging it behind me.

And yes I have a 3 bladed prop and believe it is a 19

[Andy b]

Originally Posted by kemhardt

I had the boat out two weeks ago with the kids and the boat rode ubbelievably good and the speedo read 54 mph which is about what it normal is more like 51-52.

54mph heck that's good speed. was that GPS or pitot driven boat speedo?

[mikeyt]

54 speedo or "51-52" real is far better than anything i've ever seen. The very best mine did was 49 GPS and 51 speedo. I suspect an optimistic speedo....