Logo
FULL SITE MENU

Idle rpm and Tach setting

J

jnscherr

Contributing Member
I just bought a boat with a 19

I just bought a boat with a 1983 70hp Johnson. What is the normal idle range and tachometer setting/pulse. I started the motor today with muffs and it wouldn't idle lower than 2000 rpm. Maybe it was still cold. Any suggestion would be great.
 
Tach should be set to 6P. Idle

Tach should be set to 6P. Idle speed I believe is 800 in gear and in the water. Someone please correct me if I'm wrong about the idle.
 
o.k I checked the tach setting

o.k I checked the tach setting and it's set at 6P where it should be. Can you shift from neutral into forward or reverse when it's idling at 2000 rpm or will it damage something. Is there something else I should be adjusting?
 
if you were out in the middle

if you were out in the middle of nowhere yes it would be fine.........otherwise DO NOT jam it into gear at 2000rpm

you have other issues if it wont go below 2000rpm........make sure your timer base isnt sticking......it will be a lil higher with muffs but not 2000
 
If the carbs haven't been

If the carbs haven't been cleaned in a while would that make the engine idle high if its running lean? Maybe I should rebuild the carbs and go from there. Maybe I should take it in and have a service done to it. If I take it to a mechanic what should I ask them to do? Thanks for the suggestions guys.
 
did you check to see if your t

did you check to see if your timer base was sticking?..........take the hood off and look at the linkage that goes to the piece under the flywheel. start the motor and push this towards the front of the motor and see if this helps it idle down.......be careful of the flywheel and dont let it idle at 2000 for very long.

you may also have some fuel issues. try unhooking the fuel line after you have gotten the carb bowl full (after you have pumped the primer bulb up) then start it and see if that helps.

a shop will cost you around $75-100 per hour depending on your location.
 
yes the carbs could cause the

yes the carbs could cause the problem..........does the primer bulb pump up hard?

can you see any fuel dribbling from the inside of the carb when you pump the primer bulb?
 
The primer bulb does pump up h

The primer bulb does pump up hard with no leaks...I didnt' get a chance to fire up the motor because we're expecting another cold spell but I could push the timer base forward but it springs forward again. Is it supposed to sit right back or is it supposed to be forward a little. Nokinks by the way.
 
it should have an adjustment f

it should have an adjustment for idle speed and it should sit against the adjuster...........if you can push it to the adjuster and it pops back i would suspect something is helping it do this.

could e gunk around timer base or a wire or something causing this...........
 
"O.k David, I started the moto

"O.k David, I started the motor today with fresh fuel and I pushed the timer base towards the cylinders which is that the front or the back? Anyways, when I started the motor with the choke and the lever up and gradually pushed the lever down it idled fine. Then it started to climb in idle. I pushed the timer base back and the idled slowed down, let it go and it started to climb again. Finally I gave up and shut it down. Help me please, I'm going insane."
 
check the wires coming from un

check the wires coming from under the flywheel and see if they are hung on anything causing the timer base to not return to the idle adj screw.

if not disconnect your throttle cable and see if it comes to rest at the adj screw.

if its not either one of those you will probably have to remove your flywheel and clean the gunk thats probably built up around the timer base.........something is keeping it from returning to the idle position...as you saw previously when you idled it down by hand. we just need to find the source now that we know where the high idle is coming from

let us know of your progress.

p.s. you will need a puller to remove the flywheel and a torque wrench to put it back on correctly.....it has to be torqued.
 
Sounds like you need to do a l

Sounds like you need to do a link & sync according to the instructions in your manual.
 
When you said try to push the

When you said try to push the timer base to the front you meant towards the heads right? And when I pushed the timer base back and the rpm's lowered I'm not doing anything to the timing right? Also the rpm's dropped to about 600 rpm's which is where I think it should be. I'll have a look at the wires under the the flywheel tomorrow and if everything looks o.k I should remove the flywheel and clean it up? What should I use for that? Thanks again. IBNFISHN suggested maybe a link and sync needs to be done.
 
the carbs is what i meant as t

the carbs is what i meant as the front...sorry i should have been more clear.

and yes you are messing with the timing.....the timer base advances the timing....this is what is causing the high idle.

have you messed with the remote control or throttle cables?

you might also try unhooking the throttle cable at the motor...it may be adjusted too tight.

if you dont have to remove the flywheel i wouldnt.....first see if anything else is causing the base to stick......then holler back.

the throttle arm should rest against the idle adjust screw without having to push on it.
 
Hello again. Sorry for the del

Hello again. Sorry for the delay in responding. I found out what the problem was with the idling. It's the fast idle cable. It's not returning to the idle screw. Is that a matter of adjusting or does the cable have to be replaced?
 
Back
Top