Going nuts with this motor

[troutmaster1972]

Ok 1980 70 horse Evinrude was bogging and stalling badly on me although top end was great if you could get it there Rebult all 3 carbs per instructions here including soaking with all core plugs out Then did link and sync per OMC manual Timing is dead on,fuel pump is not leaking through pulse hose when you pump bulb Took it out and though improved it was far from perfect Will not idle and stay running under about 1100 RPM or so in gear If you give it throttle slowly it will take off perfect Too fast and it will either bog and die or bog slightly then catch and take off Really dont know what to check next Anybody have any ideas? Just want to get it all right so I can winterize it at this point Thanks in advance

 

[bktheking]

Re: Going nuts with this motor

Did you adjust the idle screws properly?

 

[TLL]

Re: Going nuts with this motor

Did you remove the main jets from the carb bowls and clean them out? It sounds like you still have dirt in the carbs. Also the 3 cylinder motors need to be warm enough to accelerate well. Check the engine temp,you may have a stuck open thermostat. It needs to run at 140 deg. Take the temp at the top of the block just forward of the cylinder head.

 

[northernmerc]

Re: Going nuts with this motor

How's the compression?

 

[tashasdaddy]

Re: Going nuts with this motor

there are no adjustments on those carbs. they are fixed jets. float level could be off, flooding when accelerating, you took core plugs out but did you take all 3 jets out, and clean them. there are 3 jets in those carbs, sounds like you missed the mid speed.

http://shop2.evinrude.com/ext/index.aspx?s1=bf6ad09c53cead335fcfd8a6471c0f7f

see diagram #'s 35,33 27 are all your jets.

 

[tashasdaddy]

Re: Going nuts with this motor

http://forums.iboats.com/showthread.php?t=299680

 

[troutmaster1972]

Re: Going nuts with this motor

TLL I think you may be on to something with the thermostat issue I have noticed this motor runs really cool but being a newbie I thought that was a good thing

 

[pathfinderz1]

Re: Going nuts with this motor

If its running way cool see if the water coming out is also cool. It may not even have thomstate it it. So check and see it it is there. If it is get a new one.
Mike aka pathfinderz1

 

[tashasdaddy]

Re: Going nuts with this motor

i think i am on the right track, but get an infrared thermo and check temp. i keep one of these in my boat bag.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93983

 

[ezeke]

Re: Going nuts with this motor

The 1980 70HP and 75HP initially had idle quality problems that were discussed in service bulletin SB-1528. Most of the carburetors were modified or replaced, but you may have ones that were not. The problem carburetors were 391579 and 391580 and should be stamped with an "A" if correctly modified.

The replacement carburetors for the 70HP models were part numbers 391608 and 391609.

Place two fingers over each carburetor throat while the warmed engine is running; if the engine RPM increases when one of the carburetor throats is partially covered, that carburetor is running lean.

The 1980 and 1981 70HP models also had problems with the carburetors 391608, 391609 and 392011 discussed in SB 2025 "Hesitation on Acceleration". The suggested remedy was to replace the .037 intermediate orifice plugs with .O40 #325829. If the carburetors are stamped with a "Z", the modification has already been made.

 

[petryshyn]

Re: Going nuts with this motor

Good info ezeke !

 

[Jeff_G]

Re: Going nuts with this motor

If all else fails take the carbs apart and remove the float and gaskets, using a strong flashlight look at the main nozzle going up from the float chamber into the throat. Look for any cracks particularly between the small holes in the nozzle. If you find any the carb(s) need replacing.