90 inline 6 dies at throttle

[rosser1]

took boat out today and finally got it to crank and run. then every time i went from idle to drive or put it in gear it would die first thing. i mean just bump in to gear and dead it was. what is causing this to happen??
90hp inline 6 mariner 1979 model

 

[rosser1]

Re: 90 inline 6 dies at throttle

oh yeah it ran great with muffs in driveway, but put in lake and that is when it dies out.

 

[daveswaves]

Re: 90 inline 6 dies at throttle

oh yeah it ran great with muffs in driveway, but put in lake and that is when it dies out.

This is a classic problem, the motor cannot be tuned in the driveway and the idle must be set with the boat in the water and in gear. You have one of two things going on, the idle is too low or the carbs are too lean. Idle in gear,in the water should be around 650 rpm, in neutral, in the water around 850 rpm. If the neutral idle is ok ( i realize you cant check the in gear idle at this point) richen the idle screw on the top carb 1/4 turn, if this does not get it richen the second carb 1/4 turn, try again, if no then richen the bottom carb 1/4 turn. If still no go then go back to the top carb and repeat the process.

 

[rosser1]

Re: 90 inline 6 dies at throttle

so richen it up that would be out of carb, to open it up. right? because into carb is lean. i thank thats right.

 

[daveswaves]

Re: 90 inline 6 dies at throttle

so richen it up that would be out of carb, to open it up. right? because into carb is lean. i thank thats right.

Yes, richer is out of the carb, counter clockwise, leaner is into the carb clockwize.

 

[rosser1]

Re: 90 inline 6 dies at throttle

ok i haven't touch any of the adj screws but now it don't want to start. key is sticking. i have another post for stuck key. had to disconnect battery cause just keeps turning starter. now ever time i touch battery terminal to battery it trys to start. so now have to iron that promblem out first.... any ideas? thanks for carb help.

 

[rosser1]

Re: 90 inline 6 dies at throttle

fixed key sticking, starter solinode was stuck, ok now to adjust carb to richer, which screws need to be adjusted, i see ine on top and one to the front, beside the chock plate screen.

 

[daveswaves]

Re: 90 inline 6 dies at throttle

fixed key sticking, starter solinode was stuck, ok now to adjust carb to richer, which screws need to be adjusted, i see ine on top and one to the front, beside the chock plate screen.

The top one just holds the screen on, the one you want is on the right hand side of the carb.

 

[rosser1]

Re: 90 inline 6 dies at throttle

ok if you are looking at motor from the front, the two screws are on right hand side, but one is going into carb from side agle and larger screw is almost like it screws into the other one. almost like an "7 or T". just looking at the angles. how one come from top and other at an angle. but looks like the would touch inside carbs. So top or angled. i wish i had a picture, make a lot easier.

 

[daveswaves]

Re: 90 inline 6 dies at throttle

http://www.crowleymarine.com/mercury_parts/649/8.cfm

Item 25 in this drawing is the adjustment screw you are looking for.

 

[arsenalpsu]

Re: 90 inline 6 dies at throttle

I had the same issue with my 115hp 1984 i-6, ran good on muffs but wouldn't excelerate when in gear. I had to replace the stator as it was only cranking out 80v, now it's up to 260ish. Was only running on 3 cylinders. Now it runs fine. You need compression, spark, and fuel, what else have you checked?

 

[CharlieB]

Re: 90 inline 6 dies at throttle

oh yeah it ran great with muffs in driveway, but put in lake and that is when it dies out.

Before you start changing any settings

TEST for spark on ALL cyl's using an adjustable gap spark tester set to 7/16

Look for a bright blue 'Snap', any less and the cyl may not fire once the engine is on the water, yet it may seem fine while in the driveway.

 

[rosser1]

Re: 90 inline 6 dies at throttle

everything checked out good, sparks on all cyl. i dont have a gap on plugs, thet are the ones that are straight. runs great, ideas up in neutral, but when in gear dies, so i am going to reset carbs. and let you know the out come. thanks for all the help