1998 90 ELPTO Poor Acceleration & Performance Under Load -->Idles Perfectly

[huffduf41]

Serial # OG722004

Motor starts perfect and idles great but is very sluggish to accelerate and definitely isn't running perfect under load. Boat has a tough time reaching 40-MPH when it used to be no big deal. I spent a couple hours researching the forum and I would like to rule out any ignition issues before rebuilding the carbs.

Other than the issues above the only other thing I notice is that the tach is acting really odd, reading really high RPM when the engine is clearly not at any significant loading.

Can you please get me started on trouble shooting the ignition system? I have a multimeter w/ DVA adaptor. Thanks!!!!!!!!!!!

 

[huffduf41]

I took a look at the service manual, would the CDM (16) potentially cause what I'm experiencing?

Thanks

 

[flyingscott]

Compression and spark test need to be done.

 

[huffduf41]

FlyingScott-

You made my heart drop by mentioning the compression test, really hope you're wrong but fair assumption. Can you please walk me through the spark test? It fires perfectly at idle so I'm not familiar with diagnosing spark issues that only come up past mid-throttle.

Thanks

 

[huffduf41]

Compression test is as follows:

Top- 112
Middle-112
Bottom-110

Here is a pic of the plugs that I just replaced and have just a couple hours on. Definitely a difference with the bottom plug.

 

[racerone]

Bottom plug not firing / no fuel / too much fuel / no crankcase compression / cylinder sleeve position problem.

 

[huffduf41]

Thanks Racer, are the next logical steps to test for spark and if all is well rebuild the (bottom) carb?

Still not sure how to conduct spark test. Thanks

 

[CharlieB]

I never do just one. I want to make sure ALL are perfectly clean, float heights all the same. You wouldn't want to have to clean a different one later just because you were in a hurry this time.

While working on your motor this would be a great time to install that spin-on water separating fuel filter. This should help those nice clean carbs STAY cleaner a lot longer, with the added benefit of not worrying if any water has gotten into your fuel tank and may end up in your carbs. Great investment in your motor's health.

 

[huffduf41]

Good advice Charlie, can you please provide link to the filter you recommend? Should I still do a spark test before touching the carbs? Thanks

 

[huffduf41]

I have an inline spark tester like the one below but will this help if I'm only having issues when accelerating?

 

[huffduf41]

I did some more digging and ordered an inductive timing light....more to come.