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Slow pickup

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woozer

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"I have a 1979 evinrude outboa

"I have a 1979 evinrude outboard 70hp. When I push the thottle forward it is very slow and sounds a little rough to increase power and get the boat up to plane. Sometimes are worse than others.
I have had numerous advise and have had it checked and everything checks out fine. Compression (120ea), power packs (30kea) fuelpump timing (8 to 18deg). Nothing left to check but has anybody got some advise that could help me track this problem down. Boat is a Hartley Flarline 15ft7in so motor is ample for size of the boat."
 
PSI on all 3 cylinders are 120

PSI on all 3 cylinders are 120psi and no carb deposits. Sometimes I think it sounds like not enough fuel getting through and other times sounds like motor needs advancing though both have been checked
 
"Alright,sounds to me like you

"Alright,sounds to me like you have done some testing so I am just going to assume, that you've checked and made sure it wasnt a...fuel problem,timing issue,ignition problem,that you have the correct prop, and the carbs have been cleaned properly with link + sync done. Alright so getting back to my suggestion of doing a cylinder leak down test, compression tests are only accurate to a certain degree, I have had engines give me a reading of over 100 p.s.i on a compression test, when the cylinder is very worn out. Do a cylinder leak down and test. You can also spin the flywheel over with a ratchet and socket, feeling for the compression stroke, make sure you feel all three of your compression strokes and that they are equal. Of course making sure the kill switch is off when you do that. There could be other issues, but that is a good place to start."
 
Did you manually clean the hig

Did you manually clean the high speed jets?

Are the throttle butterflies starting to open when the scribe mark on the cam is aligned with the center of the throttle roller.... and not before or after?

Is the timer base under the flywheel sticking as the throttle is applied..... or possibly has the linkage between the top of the vertical throttle arm and the timer base come loose?

Anyy of the above problems will result in the problem you describe.
 
"Lots of questions, thanks guy

"Lots of questions, thanks guys. From the bottom up Joe, Yes carbs cleaned a to z, butterfly valves all work in sync and align perfectly with no slippage of linkages. Also had the flywheel off and all works perfectly, also checked TDC alignment.
Morten, I don't understand your question???
K Graham, Will do as you suggest. Thanks.
I will be replacing the spark plugs tomorrow as the existing ones are getting old (still good) and then taking the boat for a test run on the lake so it'll be a couple of days before I have any results. I am going to try advancing the timing on the second run just to see if this alters running and on a 3rd run retarding the timing to see where the timing should be or where the boat runs best as suggested by a mechanic. I will post the results."
 
"If Your engine does not reach

"If Your engine does not reach 5500RPM at full throtle (WOT Wide Open Throtle) it might be a sign of too heavy prop. I would guess a prop with 17" pitch might be close to correct in Your case?
If the prop is to heavy, You are starting up-hill in overdrive!"
 
"Test Results. 1st run (co

"Test Results. 1st run (cold) very good no problems, good pick up. Stopped after 10mins and idled for 2mins and then put the throttle to full and same problem came back. Sounded groggy, rough. Tried to pump extra fuel in and used choke which didn't work. So not the fuel. Observed throttle position and this only occurred if I didn't go below 1/4 throttle, if I went below 1/4 throttle then it happened. So while the revs were above 1/4 to full throttle then the motor operated fine. I didn't try to advance or retard timming. I have been advised that the stater is malfunctioning when the motor heats up. What do you think?"
 
"Stator or starter , what are

"Stator or starter , what are you talking about!!!"
 
"Look at the stator under the

"Look at the stator under the flywheel. If any portion of it has a sticky substance leaking from it, dripping downwards to the powerhead, replace it.

The above condition would indicate that the stator is failing, resulting in a voltage drop to the powerpack(s).

Should this condition exist, the stator may provide the proper voltage when cold, but would not when hot, resulting in weak and eventually no ignition."
 
I did mean stator. I just chec

I did mean stator. I just checked it and there was a slight film covering most of the stator. Hard to say if it was oil or not! Is it common for the stator to have so many holes (very small & like rill holes) all over it??? Where the screws mount it to the power head showed slight corrosion.
 
"It all looks to me that You h

"It all looks to me that You have a carburator/synch problem where at least one carb does not get the main jet started.
Do a complete synch according to the book, including carb pick-up and timing . Be sure all gaskets in the air-box in front of the carbs are sealing and in good condition."
 
"I swapped the stator over and

"I swapped the stator over and took it to the lake for trails.
The stator didn't make any difference except that it operated better when warm and the groggy takeoff still remains at low revs & speed but once revs eventually pick up theres no problem.
I tried to advance the timing, then retarded it, but it made no difference so I returned it to its original position.
My brother has suggested to adjust air/fuel mixtures on each carb. How does this sound? Ive had a look but am confused about what I found. Where the air/fuel mix screws should be there is only a bolt with a seal (neoprene or rubber) washer and the bolts cannot be adjusted because they would move if loose. Is this correct for this motor. Please advise"
 
"So, you say earlier that carb

"So, you say earlier that carburetors are very clean.Now you are asking about adjustment. That plug you are talking about is the access to the fixed high speed jet and did you remove them to clean them.There are no adjustments on these carburetors because they are factory calibrated with fixed high and low speed jets. Hope this helps ya."
 
"Yesterday I took the boat to

"Yesterday I took the boat to the lake and tested it yet again but this time it seems Ive nailed the problem. It appears the throttle was opening before advance on the cam even though roller was aligned properly on the cam to the scribe marks. I adjusted the cam so that the advance happens on or slightly before throttle opening on the cam. It always sounded like it was over fueling or fuel before advance. Sync on the carbs was okay
Now the motor picks up immediately and runs better all the way through to full throttle.
Thankyou to all who offered me advise to fix the problem, much appreciated Ed"
 
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