83 70 HP Johnson

[RICK8370HP]

I just bought this motor from a local backyard mechanic<br />Told it was totally rebuilt<br />Is it normal to not be able to gradually increase<br />your throttle on this engine.<br />If I slow increase speed I stall at just over 1/4 speed.<br />I have to pin it right down to get going, then back off.Is this normal?<br />I took my family out for the first time it ran great wide open then after about 15 minutes it started to miss at full throttle. I backed off a bit and it was okay. Got to where we were goin turned it off for 15 minutes went to restart wouldn't go. Tried and tried battery died had to leave it on the river and take a cab home.<br /><br />Anyone have any idea if I got ripped off or not?<br /><br />Thanks

 

[Bass Runner]

Re: 83 70 HP Johnson

Welcome to the forum, sounds like you lost the powerpack, when you get it home try it again, check the spark to the plugs, also check the compression, you did mix the fuel 50:1 didn't you?

 

[RICK8370HP]

Re: 83 70 HP Johnson

Went back to try and get it going the next morning wouldn't start Thought maybe if it was flooded the sit overnight would help It didn't <br />Checked for spark on all cyls when I pulled the middle plug to check the motor started and ran on 2 cyls put the plug back in and it ran fine.<br />I left the dock to head back to my lauch area about 1/2 an hour away after 10 - 15 at full throttle I had to slow down to 1/4 throttle to pass a dock when I went to throttle back up it bogged right down and stalled. This went on for awhile and even when I would put it into gear it would stall out I had to just play with it and finally I pinned it down and after a lengthy bog it decided to kick in and go <br />How important is exact 50:1 mix<br /><br />Any help on this would be great

 

[Walker]

Re: 83 70 HP Johnson

Sounds like it needs the carbs overhauled to me.

 

[RICK8370HP]

Re: 83 70 HP Johnson

This was was all supposed to have been done.<br />Complete rebuild.<br />Seems like when the engine runs for awhile at top throttle is when the problem occurs.<br />Could it be the powerpack?<br />I also can't throttle up slowly or the engine stalls. In gear and down quickly Doesn't seem right.

 

[jlehan]

Re: 83 70 HP Johnson

how long did it sit after the rebuild? and as for your fuel to oil mixture if anything u can have a little bit more oil. i had the same problem with mine when i first got it i had to rebuild the carbs but my motor sat for about a year without them doing any maintance work befor winter, would try the rebuilding the carb and get it set up correctly and go from there, the carb rebuilding is rather cheap and cant do anything but help, and this way u know when it was last done. after it died did u remove a spark plug and look at it, was it covered in gas?

 

[RICK8370HP]

Re: 83 70 HP Johnson

Thanks for the reply<br /><br />I think it did sit for awhile after the rebuild<br />There was gas on the plugs but could that have been from me flooding it.<br />does this also mean maybe powerpack heating up?<br />Also seems like the carbs are being flooded when I throttle down<br />I did try pulling the fuel line and running it dry It did seem to help when I started with empty carbs and a fresh couple pumps of the bulb. Maybe I'll enquire as to when the rebuild was done or if in fact he actually did it prior to me purchasing.

 

[Walker]

Re: 83 70 HP Johnson

Sounds like it needs the carbs overhauled to me

 

[rickdb1boat]

Re: 83 70 HP Johnson

Ditto Walker. What were the compression numbers??

 

[RICK8370HP]

Re: 83 70 HP Johnson

I think I heard roughly 135 on all 3 <br />I called the guy I bought it from and he told me the carbs were rebuilt already

 

[jlehan]

Re: 83 70 HP Johnson

still sounds like a carb problem, sound like it is flooding out, again would try a carb rebuild, cheap and easy to do<br />hope that helps

 

[walleyehed]

Re: 83 70 HP Johnson

It also sounds as though you have a link-n-sync issue on the low end....you may be starving for fuel on the top-end,(tank vent closed, air-leak in line, bad fuel connectors) or possibly getting hot.<br />The idle adjustments on that engine are fairly critical as well.<br />The carbs "may" have been rebuilt but they ain't worth a hoot if the linkages aren't timed properly between themselves, and between the carbs and the timimg advance.<br />A manual would be a good investment at this point.

 

[RICK8370HP]

Re: 83 70 HP Johnson

Thanks for the replys guys<br />The guy I bought it off is going to change the fuel pump I'll try that.If that doesn't work we'll try a new fuel tank hose and fittings.<br />This guy is very reputible around town but it seems as though he's getting frustrated with me.<br />All I know is I bought the motor for 1800.00 and it does'nt run properly. Who should be upset here.<br />I'll let you guys know what happens<br />Thanks again

 

[RICK8370HP]

Re: 83 70 HP Johnson

Well we changed the powerpack and the fuel pump<br />Bottom cyl spark was weak. Doesn't flood anymore after running for 10-15 I am able to throttle down and up slowly But it still wants to stall intermitently when i go to neutral and then forward gear with slow accelleration. But it is running much better I am able to troll after 20 minutes or full throttle and then gradullay increase to full throttle once again without stalling<br />Can anyone tell me how to bring my neutarl idle speed down? It seems to be a little high when switching from neutral to forward and reverse<br /><br />Thanks Guys

 

[RICK8370HP]

Re: 83 70 HP Johnson

For some reason my boat wants to go hard right when I let go of the steering wheel<br />Any ideas<br />I adjusted the shaft of the motor but it doesn't help.

 

[Walker]

Re: 83 70 HP Johnson

Loosen the trim tab and turn it slightly to the right. Try it and adjust more if needed.

 

[RICK8370HP]

Re: 83 70 HP Johnson

Thanks I'll give it a shot