Johnson V6 Idle Issue

[jere1972]

OK guys needs some advice my boat has been sitting awhile, just fired her up, she started right away, but she won't Idle down when sitting on the trailer, shes Idling @1500-1600, ran her on the hose for about 10 min, idle never changed, also I noticed that when using the throttle control to slowly increase rpm she sounds a bit rough (grumbles), if you go back and just move the carb linkage (no timing change) she will raise her RPM smooth and she sounds like a raped ape. I don't have a timing light, but I know in the past she always idled High on the trailer maybe around 1K I was told this was normal,650-700 in the water, but never this high, and I don't recall the slight rough running when throttle lever is advanced, the last time I had her in the water I did think something was not right she kinda vibrated a bit in the low RPM's and seemed to hesitate on her holeshot but she reached her WOT range and ran ok @WOT But seemed I may have lost a 100-200 RPM @ WOT she would hit 6k with just me and 20gallons of fuel @ 55-56mph now shes around 5600-5700 @ 46-48mph, so I'm hesitating on making any adjustments, because she was fine 1 month ago, only thing I had done was replace a new faulty CDI pack I installed a few months back, with a warrenty replacement, I did try placing the original OEM pack back in which was working when removed, but same results using the OEM that I had with the CDI pack, all Cyl are firing all cyl are getting fuel! plugs look a bit dark but they have always looked that way since Ive owned her, and they were replaced when the first CDI pack was installed! 1999 Johnson 225 OceanPro

 

[SparkieBoat]

Re: Johnson V6 Idle Issue

dont do the guess and swap thing, cost too much. clean/rebuild your carbs, do a good job. see the links in my sig below to test ignition components.

 

[emdsapmgr]

Re: Johnson V6 Idle Issue

I wouldn't get too concerned about any rpm's that the engine runs when on the trailer. It will always idle abnormally high when there is no backpressure surrounding the prop. It's a different story when the prop is submerged 2 feet underwater. You need to set that idle when the boat is floating at normal rest in the lake. Set the idle between 650 and 750 rpm's in the water when the engine is in forward gear. You can't make any assumptions about idle when it's running on the garden hose on the trailer.

 

[airframer]

Re: Johnson V6 Idle Issue

if you must troubleshoot in the driveway, you should invest in a garage sale trash can that'll hold water. gives you similar conditions and will keep the neighbors happy.
as stated above, don't throw parts at it without troubleshooting first. since it sat for awhile, did you use a fuel additive?

 

[jere1972]

Re: Johnson V6 Idle Issue

Yes on the fuel Additive always use Sta-Bil marine, I'm sort of not clear on the quick start and how it operates, have read all the CDI tech notes, I really don't see anything different happen with the way the engine runs doing any of CDI's tests, in regards to the white/Black temp wire, and I don't see the black/white wire going to the timerbase that they describe! how ever after sitting overnight I fired her up late this afternoon and she was @ about 1500 rpm, 300 down from yesterday, but I do not ever notice a quick start function take place, my understanding was quick start advances engine timing for 10 seconds??? when engine is first started or the temp is below some value! or as below 1100 rpm which is where I start getting confused (below 1100 rpm)

 

[Chris1956]

Re: Johnson V6 Idle Issue

Check to make sure the throttle and spark advance linkage is against the idle stop. I had one stick open a bit on my Johnny 150HP OB. Do you hear it come out of QuickStart? If not, your temp sendor could be bad.