140 hp evinrude 4 cyl -- intermittant power

[GrWright]

Hi. Could use some help understanding what may be causing my 140 hp to have reduced power. Sometimes it runs fine, other times I can't get my 17.5' bow rider up on plane. I don't believe it's the gas (seen that before) and I've used multiple marine gas stations and run the boat almost to empty. It really seems to lose power under load -- like when I'm pulling a tube with kids on it, which makes no sense to me.... The engine never dies, just seems to lose most of it's power. It still rev's to around 4,500 rpm. I have replaced the plugs and the spark plug wires.

Temperature seems ok per the gauge. Fuel line pump ball seems ok, not really hard, but not collapsed.

I'm thinking fuel pump or ignition system, but each is about $500 to replace (parts) I think.

 

[emdsapmgr]

What year engine is this? OMC made both a crossflow and a looper engine in the 90 degree V4 configuration. It's helpful for us to know what engine you are talking about. They have different ignition and fuel systems. That engine will seem to idle, just fine on 2 or 3 cyls. You need all 4 firing when it's under load and the prop is 20" underwater. Check for spark on all 4 plugwires when the engine bogs. (is warmed up fully.)

 

[Bob_VT]

Yes, it absolutely sounds like a dropped cylinder.

Here is an ignition troubleshooting guide. http://issuu.com/cdielectronics/docs...olor=%23222222

 

[GrWright]

Hi Guys. The engine is a 1994 model year. I will look at the guide.