Loss of Power/speed
 

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

Re: Loss of Power/speed
 

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

Re: Loss of Power/speed
 

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

Re: Loss of Power/speed
 

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.

Re: Loss of Power/speed
 

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?

Re: Loss of Power/speed
 

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

Re: Loss of Power/speed
 

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

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.

Re: Loss of Power/speed
 

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

Re: Loss of Power/speed
 

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

Re: Loss of Power/speed
 

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....

Re: Loss of Power/speed
 

I would agree with Mikey best I've had out of my 180/4.3L is 49/50mph.
and that was one up with half a tank of fuel
average WOT speed for me I would say was around the 46mph range
All boat speedo's are male and prone to exaggeration! :yes_grin:
trust in GPS

Re: Loss of Power/speed
 

well pulled the prop and doesn't look like a spun prop to me but then again I don't know what one looks like just what i have read. No shiney rubbing marks and no torn up rubber.

So now I am left scratching my head what it might be. I know to always start with the obvious and easy stuff but not sure where to go besides fuel or maybe lost a cylinder?

The 54 was by the boat speedo.

Re: Loss of Power/speed
 

Might be time to do a compression check on all of the cylinders as well as a timing check. If you read my post here, there is another fairly simple method to check for a spun hub.

Re: Loss of Power/speed
 

Ok...I have ruled out a spun prop.

I got boat out of garage and after putting sea foam in it a couple of days ago and letting that soak in the tank a bit I decided to start it in the drive way and see how it ran.

It starts right up....but one thing i do remember was that it did idle rougher then it ever has. But I wanted to get it up to temp. and see what happened. Even though it is very hot here suprisingly it took awhile for it to reach temp. Besides idle a bit rougher than normal...nothing horrible but just more noticable to me, I was going to hop out of the boat and turn the water off to the muffs. Thats when I noticed a bit of water in the blige area.

Taking a closer look it appears to be leaking from what I would call a water pump on a car engine but it appeared to be leaking from a hole and not a gasket? I need to pull up the manual and see what exactly is leaking and what that hole is for.

Just so you know I am mechanical but pressure testing is a bit over my head. I thought about replacing the rotor and spark plugs but the realized how difficult it appeared it was to access the plugs even.

Re: Loss of Power/speed
 

typically the hole is there to let you see the pump is bad. It should be fairly easy to change although I have no experience on the boat engines i can only assume it to be as easy as a car. And unless your motor does not like heat I would do a compression test now to make sure you didn't get it too hot and hurt the motor but I wouldn't think its related to your speed loss.

Re: Loss of Power/speed
 

The hole on the waterpump is a tattletail that the seal for the bearing is bad, replace ASAP. Automotive is fine just make sure it is for a vehicle with the same belt type ur boat has. Vbelt vs serpentine. Othewise the pump will spin backwards which will fight with your lower unit pump and cause overheat.

Re: Loss of Power/speed
 

Thanks for the input and advice. That is on my list of things to fix first and then go from there.

I am contemplating fixing the water leak myself ( I can do that) but thinking I am going have to take the boat in to a mechanic to diagnoise the loss of power.

I have a week already planned at the Table Rock lake with the family the 2nd weekend of Aug. and can't imagine going there without the boat. I could set here and dink with the boat till i'm blue in the face and never solve the issue then when I really have to take to the shop they wont be able to fit me in before my vacation. I'm thinking if I get it know and take my lumps atleast I can get it back in time for the trip.

I know the boat hasn't had a good tune-up in atleast 4 years so I'm thinking if nothing else a tune-up will help.

Re: Loss of Power/speed
 

Yeah uh going to table rock without a boat be like going to strip joint blind and broke. Just not the same.:yes_grin:

Re: Loss of Power/speed
 

Very true!

So does my plan of action seem logical or any other ideas?

Re: Loss of Power/speed
 

I'd think so.

Re: Loss of Power/speed
 

Either that or order the 170 dollars worth of parts save some labor costs and complete tune up yourself. Change the waterpump, then have somebody change your impeller if its been a while.

I did the tune up in the water in about an hour and a half.

Re: Loss of Power/speed
 

I stopped by the parts store last night and picked up the water circulator and sealant. Hopefull I will get it on in the next day or two and knock one thing off my list.

Re: Loss of Power/speed
 

Ok guys...I have the pump off and have cleanded the surface of the old gaskets. Do i need any sealant on the gaskets? I have read that you dont but guys do put blue locktite on the bolts. Unfortunetly I can not find the service manual for my motor so I am without the oem specs.

Thanks

Re: Loss of Power/speed
 

Your manual is the 4th one down on the third page of the "Mercury MerCruiser Manuals" section kem :)
I personally try to avoid and sealants on surfaces unless I have a issue keeping the gasket in place.
You need to use a thread sealer , not loctite on the pump threads.
Take your time and it will go fine.:wink_thumbup:

Re: Loss of Power/speed
 

Thanks for the manuals section. I had tried to locate them before but without luck.

I have installed the new pump and also purchased a new belt. I will fire up the boat tomorrow and check my handy work and see how it runs and check for leaks.

Thanks all for the advice! I still have to figure out the loss of power issue but atleast I don't have to worry about it over heating.

I also purchased a new water seperator filter and gas treatment for ethonal. The more I think about how the boat was running prior and sytems I have had before with bad gas......I am going to start there and work towards tuning it up. I know it needs it but I have been shelling out a lot of money already and will be on vacation for almost the entire month of Aug. so I can't be throwing money at the boat.

I will keep posting my findings till things are running smooth.

Re: Loss of Power/speed
 

Good deal!
Let us know how things go.

Re: Loss of Power/speed
 

Okay here is an update. I got the water circulating pump on sat. and got it all buttoned up with the new belt and water seperator filter. I also put some ethonal treatment in the gas tank to possibly help with the way it has been running rough.

Sunday I got the boat out in the driveway and hooked it up to the muffs and no leaks and it seems the more I run it the better it runs since I put the ethonal treatment in.

A couple of observations that I would like to hear input on is....

The water exhausted from the engine on the left side of the engine (if standing at the back of the boat looking at the outdrive) is warmer then the water coming from the right side.

I also happen to peek down into the carb when it was running and it appeared to have water droplets on the butterflies. This seems to be my issue then with water in the tank and the poor idling and loss of power?

Re: Loss of Power/speed
 

on top of your thermostat housing where the hoses come out and go to the manifolds there are a couple of check balls in thereone of those maybe sticky slowing down the water flow

Re: Loss of Power/speed
 

Ok thanks...I will check that out.