70 HP Evinerude Idle Problem

[ifeelika2eez]

Hi

I have between an 89- 92 model ( as far as i can tell by powerpack part number) as the last three letters of the model number are missing, Evinrude 70 HP 3 cyl that i recently bought. I had it out for one run and once you get it above idle and into gear with some revs it takes off gets up on the plane quickly and runs flawlessly. It idles ok on ear muffs but when in the water or flush barrel it seems to have too much back pressure and idles rough then spits back mainly on bottom carb that i have noticed then stalls, it also needs the key pushed in to activate choke to start even when warm. So far i have cleaned the carby's, checked the floats and made sure the needle and seats were working ok and put new plugs in. I don't have a timing light to check timing so i was wondering if the timing could cause this problem if it was out? or would a full carby rebuild make any difference? there doesnt seem to be any mixture screws in carby's just low and high speed orifice screws.it just won't idle properly anything above idle is sweet. Any ideas, solutions and help would be greatly appreciated Thanks in advance for your help.

 

[psteurer]

Re: 70 HP Evinerude Idle Problem

When you cleaned the carburetors, did you remove the low speed needle and make sure it was clean. You have a problem in the idle circuit and that is a good place to look. I believe on that carburetor, there are two or three holes in the top barrel of where the throttle plate meets (when at idle). You can see barely see them from the back end of the carburetor. Those holes permit fuel to flow at idle and need to be clear. You can also get to them by removing the welch plug on top of the carburetor (silver disk about 1/2 inch in diameter).

 

[ifeelika2eez]

Re: 70 HP Evinerude Idle Problem

thanks for the reply psteurer, yes i did remove the low speed needles and made sure they were clean, i didn't know about the holes so i will take carbs back off over the weekend and have a look at them and make sure they are clear and see how i go from there, thanks again, i'll post again with the results when i get it done.

 

[tashasdaddy]

Re: 70 HP Evinerude Idle Problem

read carb cleaning http://forums.iboats.com/showthread.php?t=299680 you also could need a link n sinc.

 

[ifeelika2eez]

Re: 70 HP Evinerude Idle Problem

everything suggested has been done, carbs have been cleaned again also making sure the three little holes were clear and link and sync. Still the same things happening, i don't know were to go from here, is there anything else i can do before i fork out $90 p/h to get it sorted. Thanks for help so far

 

[trendsetter240]

Re: 70 HP Evinerude Idle Problem

everything suggested has been done, carbs have been cleaned again also making sure the three little holes were clear and link and sync. Still the same things happening, i don't know were to go from here, is there anything else i can do before i fork out $90 p/h to get it sorted. Thanks for help so far

Sure. You can test the compression in each cylinder. Look for readings above 100psi and within 10% of each other.

Also can change the fuel filter and spark plugs. These are cheap maintenance fixes that might help your problem.

One test I would do in your shoes is when it's idling in the water, spray some carb cleaner into each carb, one by one and watch the motors response. If the engine bogs down and dies when you spray into one carb, that is ok. If it rev's up then you know that carb isn't getting enough fuel.

If a carb isn't getting enough fuel and you have cleaned it throughly you can check and replace the fuel lines for that carb.

hope that helps.

 

[tedious]

Re: 70 HP Evinerude Idle Problem

If you don't have an adjustable idle mixture, and your year range from the power pack is correct, then you have an early 89 - same model I have. They changed the carbs to the adjustable version mid-year.

My motor performs exactly as yours - idling on muffs is fine, but crummy in the water, everything above idle is fine. Someone gave me the advice to richen up the idle mixture by going down a couple jet sizes on the idle air bleed. I have installed those, but I won't get a chance to get the boat on the water until spring. Here's the thread where I got the advice: http://forums.iboats.com/showthread.php?t=361234

Tim

 

[James R]

Re: 70 HP Evinerude Idle Problem

These motors exhaust thru the prop so it follows that if you wish to set the idle the prop needs to be in the water. Rpms need to be set at about 1200 without the prop engaged and really need to be adjusted with the prop engaged in the water.

 

[ifeelika2eez]

Re: 70 HP Evinerude Idle Problem

first i would like to THANK you all for your help now i'm not sure what the exact cause was or what i may have done wrong, but i did everything that was suggested here on this post once more and when i was finished the motor kicked over and started instantly and kept idling. i took it for a run today and everything was good, although it seemed to idle a tiny bit rough but i havent set the idle properly with a tacho as i don't have one so it could be a touch low on the rpm's, thanks again for your help i realy appreciate it and Thanks for that info and link Tediuos, it appears as though i do have an early 89 model by the sounds of it, which will make things a little easier for me when it comes to parts now.