1987 Bayliner Ciera (OMC Cobra 8 Cyl. 5.7L) - Engine not going above 2,500 RPMs

[MarcLab64]

Engine runs great up 2,500 RPMs. When I give it more gas, it moves up to 2,700 RPMs tries to go higher but then comes back down. Not a fuel delivery issue. Checked pickup tube, replaced anti-syphon valve, new water/fuel filter, fuel pump is good, carburetor has been rebuilt.

I am going to check timing tomorrow, but I don't know why the timing would suddenly be off.

Any ideas? Thank you in advance.

 

[Scott Danforth]

Check the contents of your fuel filter

 

[Lou C]

While your base timing might be right; if the advance weights in the OE centrifugal advance points distributor are rusted/stuck this can happen. Id get an advance timing light and check it with the boat tied up in the water so you can safely check it at the specified RPM....

 

[Lou C]

Here are the specs for the OE distributor from my '88 OMC shop manual:
5.7
Point gap: .017"
Dwell: 27*--31*
Base timing : 8* btdc
At 3,000 rpm centrifugal advance: 20*
Total (8+20=28*)

 

[MarcLab64]

Check the contents of your fuel filter

Hi Scott,

Checked that all good. Thank you

 

[MarcLab64]

While your base timing might be right; if the advance weights in the OE centrifugal advance points distributor are rusted/stuck this can happen. Id get an advance timing light and check it with the boat tied up in the water so you can safely check it at the specified RPM....

Hi Lou C.

Thanks, I am going out this afternoon to work on it. I have the OMC shop manual with the 1987 specs. I'll postl.

Thanks again
Marc

 

[MarcLab64]

Hi,

Thanks to all that posted. Yesterday we brought an external gas tank with appropriate tubing and ran the boat, by-passing the tank, eventually by-passing the fuel pump and eventually straight to the carburetor and the problem is with the carburetor. I will remove it, check it out and if I can't fix, I'll just get a rebuilt one.

I will let you know how it turns out.

Marc L.