05 f150 compression help needed.

R

Reel Aggressive

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Sep 11, 2010
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I have a 05 Yamaha f150and I did a compression test today.
From top of motor to bottom
cylinder 1 - 168psi
Cylinder 2 - 168psi
Cylinder 3 - 152 psi
Cylinder 4 - 152psi

The sets were identical in compression so I have no clue what's going on.
I don't know if its a fuel injection thing or what...

I tested with throtle in the idle position.
 
JB

JB

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45,907
Re: 05 f150 compression help needed.

If your question is are those numbers okay, they are.
 
R

Reel Aggressive

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Re: 05 f150 compression help needed.

i took the boat out yesterday.
At full throttle it runs at 3800 rpms at 25mph
Seems kind of weak but it is pushing a 05 Polar 2110 Bay center console with 7' tower
Has a 4 blade 993204-14 3/8 X 18
Could it be a prop issues?
 
R

Reel Aggressive

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Re: 05 f150 compression help needed.

I don't know.
I purchased the boat from my boss.
He purchased it brand new and it came stock with a 3 blade prop.
He tore it up on an oyster bed and so he purchased this stainless 4 blade.
To be honest I doubt he did any research other than its stainless...
He told me that when he switched over he lost a lot of top end...
I have the original prop should I get a new one with the same build and put it on?
How much should I be paying?
I took it out and if I left it at wot it would slow down slightly over time unless I pumped the throttle lightly at top end.
 
9

99yam40

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Sep 7, 2008
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9,281
Re: 05 f150 compression help needed.

I would take it to a Yamaha shop and have them test the motor with a Yamaha test prop for that motor and see if the motor has a problem before running any more, as you do not want to have to replace a power head if it has a real problem and you hurt it beyond repair

did you look to see what the site I showed said about your set up?
 
R

Reel Aggressive

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Re: 05 f150 compression help needed.

I did and the chart measured it up to 6000rpms
If this has been bad for too long am I looking at buying a whole new outboard?
 
9

99yam40

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9,281
Re: 05 f150 compression help needed.

You will need to test to see what is going on.
leakdown test would be the 1st thing to see if the motor has sealing problems
 
Silvertip

Silvertip

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Sep 22, 2003
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28,771
Re: 05 f150 compression help needed.

No need to spend money on diagnostics or a prop at this point. Go to the Yamaha web site and click PERFORMANCE BULLETINS. Then select your engine and boat type. If your exact boat is not listed, select one that is close in type, weight, and length. Check the test report as they always list the prop type including the part number used in the testing. That's your starting point.
 
R

Reel Aggressive

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Joined
Sep 11, 2010
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Re: 05 f150 compression help needed.

I was curious if the motor could get past 3800rpms today so I went over to my boat and hooked the hose up. In Idle the motor has no problem revving up to 4500rpms (I think its a rev limiter)
THe motor sounds clear but I know that means nothing because it not pushing a load...
 
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