150 Evinrude will only idle on the muffs in the driveway

[duppie03]

Good morning,

I have a 1986 150 Evinrude, that has the VRO disabled and is running a 50:1 mixture.

My problems are that I can get the motor to run fine on the muffs in the driveway, but as soon as it has the back pressure on it in the water it will only idle for a few seconds and die.

I have checked the compression, and thats fine. I have checked the spark and thats fine. I soaked the carbs over night and blew them out with air, so they are clean.

I spent three hours at the ramp last night trying to get the idle adjusted, and the longest I got the motor run was about 30 seconds.

I would really appreciate any advice, or help from anyone at this point.

Thanks in advance,

Aaron

 

[Silvertip]

Re: 150 Evinrude will only idle on the muffs in the driveway

So what is the "idle speed"? Putting the engine in the water adds exhaust restriction which affects idle speed. If it's too low the engine dies. Soaked the carbs overnight?? Disassembled fully and then rebuilt or just soaked?? Unless they were totally disassembled and every passage made squeaky clean you accomplished nothing.

 

[duppie03]

Re: 150 Evinrude will only idle on the muffs in the driveway

THe carbs were completly disassembled and rebuilt with new kits, and they are squeaky clean. On the muffes in the driveway the engine idles at 1100rpms.

 

[boobie]

Re: 150 Evinrude will only idle on the muffs in the driveway

What was the compression? Sounds like you need a GOOD De-carb job due to stuck lower rings.

 

[HighTrim]

Re: 150 Evinrude will only idle on the muffs in the driveway

How did you test spark? I would say that you are not running on all cylinders.

If you checked them with an inline light, or by holding the plug to the block, that is not good enough.

You need an inline tester with the gap set to 7/16". The spark should jump that gap with a bright blue ZAP!! Should be a steady spark.

 

[emdsapmgr]

Re: 150 Evinrude will only idle on the muffs in the driveway

You need to have sufficient idle rpm's to counteract the depth of the water when the boat is floating. Hard to tell what the engine rpm's will be at idle when the engine is running on the trailer. You need to make be sure to set the idle to 650-750 rpm- set when the engine is floating in the water, and it is in forward gear. That's probably closer to around 900 in neutral in the water. Weak ingnition componets tend to fail when they heat up to normal operating temps. If you checked spark when the engine was cold, you may not have an exact read on the condition of the ignition system when it starts to heat up. I'd follow High Trim's advice and use an inductive timing light to check the spark when you have it running.

 

[duppie03]

Re: 150 Evinrude will only idle on the muffs in the driveway

Thank you for all the great feedback. I plan on leaving work early tomorrow to get an early start before the weekend rush at the ramps. I'll update on Monday.