70hp evinrude won't idle

[jepsat]

I need the best boat mechanic i can find for my rude that won,t idle when trim is set all the way down. i took it to the boat shop they couldn't figure it out after rebuiling carbs checking timing, compression 100psi all cylinders, they gave it back to me said they don,t know whats wrong with it thought something internal was wrong<br />so i ordered a complete rebuild kit completed rebuild with nothing seeming amiss yet still only has 105psi compression all cylinders and still won't idle (I give) sending out an S.O.S.

 

[jepsat]

Re: 70hp evinrude won't idle

also it isn't an idle speed problem or an exhaust restriction both have been checked thoroughly i'm told these motors genereally have 120-125psi compression so something more fundamentally must be wrong has everyone in this area stumped it is a low time motor.

 

[DHPMARINE]

Re: 70hp evinrude won't idle

Let me guess .. low time motor .. compression down a bit .. just rebuilt .. Stalls when trimmed down .. Got me guessing unless it's a 1987.<br /><br />DHP

 

[mebusybe]

Re: 70hp evinrude won't idle

I have a 70 Evinrude that is also having the same problem. It is in to be fixed now. They told me it should be ready by tommorrow or the next day. If they correct it. I will find out what the problem was and write back. What year is yours?

 

[rcgt78]

Re: 70hp evinrude won't idle

So, it's related to the position of the engine.<br /><br />Fuel in carburator bowls. But they were rebuilt.<br />What about cooling water in cylinder head and exhaust. Could it be a leaking gasket letting water into places where it shouldn't be. <br />Or is it a loose connection somewhere causing the engine to die.<br /><br />Check for spark, fuel restriction (spray fuel direct into carbs), loose connections, water in cylinders, etc.<br /><br />I hope you soon find the problem and can get the boat running. <br /><br />By the way. I have a Johnson 60Hp -89 that has the compression readings at about 95 in all cylinders. But the engine runs still fine at idle. Just some common sputtering/sneezing and no top end power. I'm considering a rebuild soon.<br /><br />B.R.<br />Robbi

 

[jepsat]

Re: 70hp evinrude won't idle

the motor is an 89' with no signs of fuel restrictions as I pull fuel lines off it is holding fuel pressure there is no sign of water in cylinders i.e.plugs are not being steam cleaned also no sign of water seeping past any gaskets, have put spark testers on it spark is fine spraying carb cleaner directly into carbs makes little difference.there is no backfiring or sneezing indicating lean condition or electric connection problems. everyone here is stumped am considering trying to find someone with same motor<br />that runs well and swapping carbs(I know good luck).

 

[Silvertip]

Re: 70hp evinrude won't idle

You said carbs have been rebuilt, but were they soaked, all the internal passages cleaned thoroughly and then blown out with compressed air?. Idle speed and mixture set wrong (adjust in the water) and timing set correctly?

 

[Basscat 1]

Re: 70hp evinrude won't idle

I need the best boat mechanic i can find for my rude that won,t idle when trim is set all the way down.

Will it idle in the water if it is trimmed up? <br />What about on muffs, will it idle in the up or down position?

 

[jepsat]

Re: 70hp evinrude won't idle

carbs have been soaked and blown out with compressed air- it will idle in water if it is trimmed up just before prop breaks the surface-it will idle on muffs regardless of trim position so it has nothing to do with carb position its the back pressure thats killing it but can't figure out why.

 

[jepsat]

Re: 70hp evinrude won't idle

also timing was checked by myself and boat shop it was right on I also checked tdc timing by measuring #1 cylinder piston and marking flywheel it was right on so no flywheel slippage.

 

[Basscat 1]

Re: 70hp evinrude won't idle

In the water you need to adjust your idle up due to the back pressure.<br />As a rule of thumb, on muffs it will idle somewhere in the neighborhood of 1000 rpms, give or take.<br />In the water, set the idle at 650 in gear.

 

[jepsat]

Re: 70hp evinrude won't idle

i have adusted the idle in water but to get it to idle the rpm's are to high and it's very hard on the transmission welcoming any other suggestions.

 

[Basscat 1]

Re: 70hp evinrude won't idle

After months of searching, my idle problem turned out to be bad reeds. The best way to check them is to remove the reed blocks and hold a flashlight up to them and look for light around the edges. If you see light, its time to replace them. I ended up putting in a set of Boyesen Reeds, and it was the best $100. 00 I have spent on my boat. It idles smooth. As older engines begin to wear they start to loose compression, but more importantly they start to loose crankcase pressure which is vital to reed operation. At the same time, blowby caused from the worn rings enter the crankcase.<br />The Boyesen Reeds help compensate the loss due to their dual stage design.<br />Here is a thread talking about them. web page

 

[Blueclaw]

Re: 70hp evinrude won't idle

Just hold a white piece of paper a couple inches in front of the carb in question. If you see a mist between the carb and paper the reeds are bad.<br /><br />I'd re-check your float settings and timing with the motor in the water.

 

[Basscat 1]

Re: 70hp evinrude won't idle

Sometimes that trick works, but sometimes it dont, as was the case with my engine. The best way is to do a visual inspection of the reeds.

 

[roger46982]

Re: 70hp evinrude won't idle

Replaced VRO with standard fuel pump and still won't idle trimmed down in the water, just fine on muffs., when checking carb i found it has two diff. sized orfices, what should the J7OTLCEM take. Maybe reed replacement time?