1977 70hp evinrude running sluggish

[cjleysath]

been having trouble accelerating: need to hit elec. choke and then runs fine. Waiting for manual to arrive before attempting to rebuild carbs. Had to be towed back to dock recently after stall and no restart. Pulled plugs and cranked to clear cylinders and had milky white fuel exiting one cylinder; lower one. No sign of this crud in upper two. Plugs wet but clean. Last season's fuel w/ stabilizer and Sea Foam.

Any thoughts?
Thanks

 

[fireman57]

Re: 1977 70hp evinrude running sluggish

Sounds like a leaky head gasket. Letting water in cylinder.

 

[cjleysath]

Re: 1977 70hp evinrude running sluggish

Thanks for the reply:
I feared the head gasket may be the culprit. Is this a difficult repair or a do-it-yourself'er. I'm assuming my repair manual will explain this a bit. Could this be the cause of my poor acceleration as well?

 

[fireman57]

Re: 1977 70hp evinrude running sluggish

edit

 

[fireman57]

Re: 1977 70hp evinrude running sluggish

Easy fix just an expensive gasket. If you have a manual it will tell you the tightening procedure. There is an order you want to follow and proper torque is a must. After running for a few hours you will want to retorque them. If the search feature is up and running again you can try it as I know that there are several threads that have this information in them. Could definitely be your acceleration problem as water doesn't burn as well as premix. Doesn't lubricate worth a darn either.

 

[Chinewalker]

Re: 1977 70hp evinrude running sluggish

Could also be water in the fuel. If the head gasket turns out to be alright, check the carbs...
- Scott

 

[jim_in_day]

Re: 1977 70hp evinrude running sluggish

We are seeing a lot of problems related to fuel, milky white and sometimes chunky. Easy way to tell if its from your fuel tank. Pull fuel connector at engine, depress the little ball in the fuel connector and pump your bulb. If it comes out white and milky, its in your tank. Sure easier than pulling the head looking for a bad head gasket

 

[papasage]

Re: 1977 70hp evinrude running sluggish

if it is 1 cylinder it is probabley head gasket .

 

[fireman57]

Re: 1977 70hp evinrude running sluggish

Since the big hike in gas prices the fuel doesn't seem to last more than a few weeks as best. Guess to make more money they are not putting the additives in that they used to. Good suggestion by jim.

 

[cjleysath]

Re: 1977 70hp evinrude running sluggish

My initial thought was that it was the fuel but I'm good about using stabilizer and keeping tank full. Junk in just one cylinder leads me to think it's the gasket. I did check out the fuel coming through fuel hose; looked fine. Also, hard cranking when stuck on the water leads me to think water doesn't compress too well... though my battery was dying

 

[leysathcj]

Re: 1977 70hp evinrude running sluggish

Well it's a year later.... Changed the head gasket and ran well for a couple of trips but continued to require choke to plane out. Problem progressed worse as the 2006 season went on. Currently have carbs off for rebuild and will do the fuel pump as well.

Questions: I've read that these carbs should not be "dipped" in carb cleaner for any length of time due to some coating on the casting...although alot of threads comment on having done this. Any difference between marine carb cleaner and automotive? My manual requests use of a "test wheel" in replacement of the prop for max. rpm adjustment. Is this really required?

Will put this all together, link/sync, check timing and give it another go.

Any thing else I should be looking at while I'm in there?

 

[Kevin W]

Re: 1977 70hp evinrude running sluggish

I have never heard dipping had any effect on coatings other than paint.
carb cleaner does eat rubber, gaskets, plastics etc..

to link/sync correctly you need to get near max rpm in gear in the water.

A test prop is not needed but it definately helps.

just make sure all adjustments are done in the water not on muffs .

 

[leysathcj]

Re: 1977 70hp evinrude running sluggish

Kevin
thanks for the response. Running "near max rpm" w/ boat in the water...can this be done while still strapped to the trailer, tied to a dock or am I screaming across the water and risking my life.

 

[Kevin W]

Re: 1977 70hp evinrude running sluggish

I can't say i have done it.
Most shops have test tanks to do this.
I would be a little worried about strapping it to the trailer and putting the hammer down with a standard prop on there.
Maybe someone here has a solution.

 

[fireman57]

Re: 1977 70hp evinrude running sluggish

Take a buddy along to drive on a smooth water evening. I have heard of people doing this on the trailer and also heard of them ending up with the boat in the bed of their pickup. The link n sync should get you very close. I don't know that you need a test prop.

 

[leysathcj]

Re: 1977 70hp evinrude running sluggish

Hi everyone & thanks to all for your help so far...

The boat is running better after carb and fuel pump rebuild, new fuel lines, link & sync, ect. No longer need to choke to get up to speed BUT it does hesitate when I hit the throttle before kicking in. I can minimize this by accelerating slower but if I "jump on it" from idle speed, she hesitates before taking off. No "cough" from the engine just a lag of about 1 sec.

Also while running in my driveway (w/ muffs and in a barrel for exhaust pressure) she occassionly "misfires,coughs and/or spits" which drags rpm's down before recovering. Doesn't happen so much if I increase idle speed. Swapped coils around as I was getting an erradic tach reading from #1 cyl. but it didn't make a difference (Tach would occassionly drop before recovering). This went away after moving coils so maybe just dirty connections.

Anyway, I'm no mechanic but I'm enjoying the $ savings and getting intimate w/ my boat. Please help if you have advise on above.

I'll be in the water tomorrow to adjust max rpm, check timing and idle speed.
Thanks

chris

 

[Lodgepole]

Re: 1977 70hp evinrude running sluggish

I bought a 78 70 hp that would hesitate on acceleration and would die off trying to push boat onto trailer. Thermostat was bad, replaced and cured the problems. Water cooler than opperating temp makes a motor run cold.