8.1 volvo in Cobalt not reaching RPM

J

jlbpropilot

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May 2, 2010
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Hi, hopefully someone alot smarter than I can help figure out my problem. We recently purchased a 2001 Cobalt with an 8.1 Volvo in it. After purchasing we had captains call added and ran the boat for the first time this weekend. We are extremely disappointed in the performance of the boat, it is a 226 and we are able to get 40mph tops and just above 3000 RPM. As slow as the boat accelerates there has to be something wrong. After the first run we changed the fuel filter since it had not been changed since 2005 and it made no change whatsoever. Anyone have any suggestions? Thanks
 
Bondo

Bondo

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Re: 8.1 volvo in Cobalt not reaching RPM

After the first run we changed the fuel filter since it had not been changed since 2005 and it made no change whatsoever.
Click to expand...

Ayuh,... Welcome Aboard,......

I'd start with a general Full Tune Up,+ service...
That might find the problem, or it could be something more...
 
B

boat127

Petty Officer 2nd Class
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Apr 18, 2010
Messages
196
Re: 8.1 volvo in Cobalt not reaching RPM

is there marine growth on the hull
 
J

jlbpropilot

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Re: 8.1 volvo in Cobalt not reaching RPM

No the hull is clean, we run on a freshwater lake and its on a trailer when we arent using it.
 
Juniinc

Juniinc

Petty Officer 1st Class
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Jan 16, 2010
Messages
221
Re: 8.1 volvo in Cobalt not reaching RPM

prop pitch is?
 
J

jlbpropilot

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Re: 8.1 volvo in Cobalt not reaching RPM

sorry for my ignorance but I'm not sure of the pitch. It is a counter rotating stainless prop. I would have thought with 400hp this boat would rocket out of the water.
 
K

KJSmitty

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Aug 9, 2008
Messages
179
Re: 8.1 volvo in Cobalt not reaching RPM

jlbpropilot said:
Hi, hopefully someone alot smarter than I can help figure out my problem. We recently purchased a 2001 Cobalt with an 8.1 Volvo in it. After purchasing we had captains call added and ran the boat for the first time this weekend. We are extremely disappointed in the performance of the boat, it is a 226 and we are able to get 40mph tops and just above 3000 RPM. As slow as the boat accelerates there has to be something wrong. After the first run we changed the fuel filter since it had not been changed since 2005 and it made no change whatsoever. Anyone have any suggestions? Thanks
Click to expand...

Greetings jlbpropilot,

First off, the 226 is a pretty heavy boat (and a nice one). I have a 2003 220 Cobalt with the 320hp and its not much lighter. Is it a DP or single (OK, I no more than posted and just read your post above:D)? Regardless, you should be getting mid 50's at WOT.

Something is definitely wrong - I wonder if they messed up the throttle linkage at all. Do you have a "Perfect Pass" or other throttle/speed controller? You mentioned the captains call and I know my True Pass has items and linkage attached to the risers on one side. One never knows what they might have forgot or just hooked up wrong etc..

Good luck

Cheers
 
Fun Times

Fun Times

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Re: 8.1 volvo in Cobalt not reaching RPM

Did you try trimming the drive up a little while at speed, Or did you leave the drive trimmed all the way down?
 
J

jlbpropilot

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May 2, 2010
Messages
5
Re: 8.1 volvo in Cobalt not reaching RPM

No perfect pass on this boat. It seems as if the throttle is moving the entire length, I dont suspect a throttle linkage problem. As for the trim it was raised a bit once planed out on the water and it did add some speed but nothing significant. Looks like a trip to the cobalt dealer is in my future:mad:
 
J

jlbpropilot

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Re: 8.1 volvo in Cobalt not reaching RPM

Just got the boat back from the Cobalt shop. Goes like a scalded dog now. All it took was a new set of spark plugs if you can believe that.:)
 
Fun Times

Fun Times

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Re: 8.1 volvo in Cobalt not reaching RPM

jlbpropilot said:
Just got the boat back from the Cobalt shop. Goes like a scalded dog now. All it took was a new set of spark plugs if you can believe that.:)
Click to expand...
Thanks for the update.;)

Good to hear it was an easy one and nothing serious.:)

Those pesky spark plugs will get you every time.:p
 
M

Mike250

Seaman
Joined
Dec 9, 2008
Messages
69
Re: 8.1 volvo in Cobalt not reaching RPM

Glad it's fixed!

I had the same boat/motor combo and it ran 63 mph on GPS with the CC open. Hang on!!!!!!

Sorry, it had a Bravo I not a III. I'm guessing 60 mph on yours. Speedo should show about 80+.
 
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