1976 70hp With CMC tilt (Boggs)

[mobiletec]

Hi I Have a 1976 70 hp Evinrude that was running good but had sat for about 2 years. Rebuilt the carbs and installed a water pump. Bench tested (with water hose) seems to run good in and out of gear. Installed it on a 16 foot fiberglass boat. Here`s my problem! Started, idled good, but put it in gear and it will troll along 1/4 throtle, But then over 1/4 it Boggs down and wants to stall.(boggs)
choking, makes it worse so I don,t believe lack of fuel. Could this be a timing issue? Could it be a linkage adjustment messing with timing? Sometimes you can slowly accel and get the boat moving but it about troling speed no more. If I start the engine and use the warm up lever it revs up no problem. Any help would be great!!!

 

[ezeke]

Re: 1976 70hp With CMC tilt (Boggs)

With no load, your motor can seem to run fine one cylinder. You are probably losing one under load, so you need to do a compression test, followed by using an inductive timing light to check the spark on the running motor under load.

 

[tashasdaddy]

Re: 1976 70hp With CMC tilt (Boggs)

agree^^ also:
Ethanol and fuel lines
replace all fuel line with Alcohol resistant lines. Ethanol deteriorates, the rubber lines, then they start to sluff off on the inside, going directly to the carbs. Settling to the bottom of the bowl. Contaminating the carbs high speed jets. clean a rebuild carbs, flushing fuel line before connecting to carbs.

 

[mobiletec]

Re: 1976 70hp With CMC tilt (Boggs)

Thanks Gentlemen. Before putting it in the water i did a compresson test had 130 even on each cylinder. One thin i did do is hook up my old fuel line from last year that was on my merc. I`ll try the timming light. So i hook it up to each spark plug wire while engine is running to see for spark I`m i correct?And i`ll also check my carbs again. Ohh by the way i used Tygon and repaced all the fuel lines and the fuel pump Thanks. Ps i replaced the carb fuel line with Tygon but the main lines from pick-up to fuel pump are rubber Gate Brand should i replace them also

 

[ezeke]

Re: 1976 70hp With CMC tilt (Boggs)

An inductive light has clamps that go around the spark plug wire so you don't remove anything. The light will let you know that the plug is getting fire at any speed so you can see what happening as you go along. The better lights have a digital tach so you can monitor the activity as you work.

 

[mobiletec]

Re: 1976 70hp With CMC tilt (Boggs)

Well took the boat out this weekend and here`s what found. Did a link and sync. Started right up no problem. Then i Took it out for a spin and the same thing BOGGS after 1/4 throtle. So I pressed in the key to hit the choke and then throtled right up and it took off no problem. Full throtle for 15 20min no problem. Then i cycle it back and forth from full to 1/4 and it BOGGS again. Hit choke and works fine. Ohh by the way i didnt end up changing the coils or power pack as i checked the spark with timming light on all 3 holes even with the boat full out resting against the dock. Any Thoughts as to what might be happening. Installed new fuel pump and lines last year. And rebuilt carbs with aftermarket carb kits could this be the problem. If it were the high speed jet would it do the same after i hit the choke.