2000 125 ELPTO Performance issues.....

[capri125]

I bought a Bayliner Capri 1800 with a 125 ELPTO 2+2 this summer. I have taken it out quite a few times now and just now started to notice the issue. It will only rev up to about 4200 RPMs and run at about 35 MPH. When i go WOT it hesitates big times, you can hear and feel it skipping/trying to pull the power but it just cant. It has a 21P prop on it. I have put new spark plugs and fresh gas with additive and still nothing. Any suggestions or recommendations would be much appreciated. I understand the way that the 2+2 feature works and it has no issues kicking into 3/4 cylinders. Compression is at 95psi on all 4 cylinders. Not sure where to go from here. Im not all that great with boats/motors, but am def a DIY type. Thank you in advance for any help.

 

[pigeon laker]

Recheck your compression.Pretty sure all cylinders should be around 120psi.

 

[Texasmark]

I just ran your numbers through the BAM prop slip calculator and your instrumentation is reading correctly for having a 20% (prop) slip which is OK as I see it for that rig.

My manual on the 3 and 4 cyl engines states that if compression is lower than 120 expect problems. So if the gauge is accurate then you are loosing top end due to lack of compression.

My 2c,
Mark

 

[capri125]

I just double checked the compression and the top two cylinders are at 100 and the bottom two are at 105. Is there something else that I should check or look into. I just can't believe that it would be performing this bad with the compression the way it is.

 

[capri125]

...

 

[Texasmark]

Ok two tests:

1. What is the condition of the squeeze bulb at WOT? If collapsed engine is sucking and can't get enough fuel. If soft, squeeze it a few times and see if things change. If so, look at a fuel pump kit.

2. Over the years, spark plugs usually failed at the higher rpms. Hard to check an oil soaked surface gap but a set of new ones might be in order. Next would be a timing light on/near each spark plug when you feel the surging. Spark surges are usually more of like a switch on and off whereas fuel is more drawn out.

100-105 may be ok if the load on the engine isn't all that bad.....clean hull planed out, smooth water, trim set to best speed, light load sort of things.

Mark