OMC 120 will not produce powre under load

[arc68]

Hi,
I have a Renken 18 ft i/o OMC120 with a electric shift.Engine will not produce power above 1500 rpms. Carb has been rebuilt, compression was 120,123,123,120, timing at 8 btdc. Electric shift off a OMC 120 set up. Boat had OMC800 cable shift did same thing. What am I over looking?

 

[Levinz11]

Re: OMC 120 will not produce powre under load

When was the last time you did a FULL tune up? Changed fuel filters?

 

[arc68]

Re: OMC 120 will not produce powre under load

I will replace it today and try it at the lake next go around. Changed fuel pump and filter in April of this year.
Nice boat.

 

[Levinz11]

Re: OMC 120 will not produce powre under load

I will replace it today and try it at the lake next go around. Changed fuel pump and filter in April of this year.
Nice boat.

Thanks dude. I would start with points, condenser, cap, rotor as these are cheap and really need to be done annually anyway.

 

[arc68]

Re: OMC 120 will not produce powre under load

Aready done condensor and gapped points, 17mm was what I was told
. Cleaned cap rotor and rotor button and megger check good. Will replace wire set and inspect carb for contamination.
Thanks for the suggestions.

 

[Levinz11]

Re: OMC 120 will not produce powre under load

Aready done condensor and gapped points, 17mm was what I was told
. Cleaned cap rotor and rotor button and megger check good. Will replace wire set and inspect carb for contamination.
Thanks for the suggestions.

.017-.019" is point gap. What's your timing looking like?

 

[arc68]

Re: OMC 120 will not produce powre under load

After further examination brought #1 tdc , rotor cap was not in the proper position it was around 20 degrees off atdc.All marks are missing off of timing plate.Will realign timing to proper marks.

 

[arc68]

Re: OMC 120 will not produce powre under load

Went to lake today after preforming a carb rebuild and adjustment, chaneg all fuel filters,retimed engine and set points. Engine still bogg down and will not make power,after running engine a while it began to loose power at 10kts at full throttle. Beganing to suspect internal engine damage or failed compnets. Any thoughts??

 

[NW Redneck]

Re: OMC 120 will not produce powre under load

How old are the fuel hoses? They could be deteriorating on the inside especially if they are older hoses and you are using ethanol gas. Have you checked the tank pickup fitting/tube? Could have a partial blockage. Checked for water in the tank? Do you have a water separator/filter?

 

[arc68]

Re: OMC 120 will not produce powre under load

New fuel lines and fuel tank drained and cleaned with fresh mid grade gas.I think I found the promblem, while checking timing with timing light did not notice timing retarding to 4 degrees after advancig, stay advance until engine was shut down. Check for parts and will update later.
Safe Boating