Mariner 175 low power

[peterpeter]

We have a Mariner 175 on a 6m RIB. The Engine starts good, idles ok, no load revs 6000. When under load can only get 3500 rpm. Recently rebuilt following over heating seize, new pistons and rings, compression 5% to 10% down.

 

[KCLOST]

Re: Mariner 175 low power

Tough one to answer... But don't rev the engine above 2500 in neutral, you could break some pretty important components reving that high without a load....<br /><br />Are you breaking in the motor correctly? Like you would with a new motor?

 

[lmoreau]

Re: Mariner 175 low power

I've seen engines to similar things, and it's usually the carbs. Give em a cleaning.

 

[peterpeter]

Re: Mariner 175 low power

We've checked the timeing staticly, all ok.<br />I know the timeing auto advances above 2600RPM when under load. My thoughts are a fuel problem,<br />any clues on fuel pressure delivery at carbs and or sucing in air etc.<br />Thanks for any info Peter.

 

[peterpeter]

Re: Mariner 175 low power

We've checked the timeing staticly, all ok.<br />I know the timeing auto advances above 2600RPM when under load. My thoughts are a fuel problem,<br />any clues on fuel pressure delivery at carbs and or sucking in air etc.<br />Thanks for any info Peter.

 

[achris]

Re: Mariner 175 low power

Peter,<br /><br />Saw this on an engine about 15 years ago. Took forever to find it. Long story short, firing order. Someone had switched the wires for cylinders 2 and 5 at the power packs. I realize the chances of that being the problem in this case are several squillion to one, but ya never know. Easy to check and rule out.<br /><br />Chris........

 

[KCLOST]

Re: Mariner 175 low power

Now that's thinking... Could be any of them 1/2, 3/4. 5/6, or any combination at the packs... Worth checking if you have a good manual and know the proper connections...<br /><br />achris, thumbs up...

 

[achris]

Re: Mariner 175 low power

The firing order is 123456. If you have a multi spark tester you can look at an angle and see the sparks 'ripple' along the tester. That's how I found that one years ago. Especially if the engine has just been pulled down, really easy to switch a couple of wires.<br /><br />Chris..........