Lack of Power Problem

[phillyg]

1993 Rinker 300, 30', repowered with 5.0 Mercruisers in 2005, with I think the original Bravo II outdrives. Went out a couple of weeks ago; no problems. Tried to go out today and the STB motor wouldn't go over 3000rpm. I could get to about 18mph and could barely get on plane. It felt as if I was dragging a crab pot along the bottom, not that I've ever done that, but it was like the boat was being held back by something.



Got back to the dock and felt around the drives and nothing was attached. The props spin freely. There were no lines hanging over the side. I disengaged the shifter and the motor spins up fine. I've never experienced a drive problem so I don't know what to expect. The drive fluid reservoir is at the correct level, and there is no discoloration of the fluid. If the drive is leaking water in, wouldn't it show up in the fluid? I know the gimble bearing will click when the drive is turned to one extreme or the other and I haven't heard that. If the drive is failing, would I experience this type of problem?



The only solution I have is to have the boat pulled out of the water to have the drives inspected. Or, does anyone have any idea that something else could be the problem?

 

[NHGuy]

Re: Lack of Power Problem

http://forums.iboats.com/showthread.php?t=295070 This is a thread with troubleshooting ideas when the problem is lack of wide open throttle RPM.

 

[phillyg]

Re: Lack of Power Problem

http://forums.iboats.com/showthread.php?t=295070 This is a thread with troubleshooting ideas when the problem is lack of wide open throttle RPM.

Thank you. I looked at all those potential problems and only noted a couple that could be the issue, and I'll look into those today. Since the motor easily spools up to 4000rpm (and would go higher) when dis-engaged from the drive, my backyard mechanic mind thinks it has to be a drive issue. But then again, I could be very wrong.

 

[daydreamer1252]

Re: Lack of Power Problem

as has been stated here in the past (dozens maybe hundreds of times) probably 3-4 "good" cylinders is enough to spool an engine when not under load.....under load you really need all of 'em to make the boat go....follow the list and check all of the items, it was compiled with much thought by very experienced people....if you read more here you will also see that LOTS of people pick and choose from a troubleshooting list and end up having to go back and follow through to really get to the problem.....just my thoughts....hope you find the issue soon summer's wasting....

 

[phillyg]

Re: Lack of Power Problem

as has been stated here in the past (dozens maybe hundreds of times) probably 3-4 "good" cylinders is enough to spool an engine when not under load.....under load you really need all of 'em to make the boat go....follow the list and check all of the items, it was compiled with much thought by very experienced people....if you read more here you will also see that LOTS of people pick and choose from a troubleshooting list and end up having to go back and follow through to really get to the problem.....just my thoughts....hope you find the issue soon summer's wasting....

You're right about the list. I just had an opportunity to speak with a Mercruiser mechanic who told me the drive was not the problem. Again, I don't know squat about outdrives and I proved it. One thing I didn't give weight to on the list was a missing or dead cylinder. That where the mech told me to look first. I had thought a missing cylinder would have been noticed by me. So yes, summer's awasting and I got to get back on the water, soon. Thanks.

 

[Bondo]

Re: Lack of Power Problem

You're right about the list. I just had an opportunity to speak with a Mercruiser mechanic who told me the drive was not the problem. Again, I don't know squat about outdrives and I proved it. One thing I didn't give weight to on the list was a missing or dead cylinder. That where the mech told me to look first. I had thought a missing cylinder would have been noticed by me. So yes, summer's awasting and I got to get back on the water, soon. Thanks.

Ayuh,.... I'd start with a diagnostic tune up, includin' a compression test, 'n have a look at the contents of the fuel filter....

If ya don't find yer problem there, continue on Don's list....

'n as noted,... a V8, runnin' on 4, will rev to the Moon, without a Load....