1984 70hp Evinrude stalling on acceleration

[tommyarmour]

This is what I have done:

Compression is 118/118/119
New Plugs
New Gas Tank
New Primer Bulb
New Fuel Pump
New Rectifier
Silencer Gaskets
All 3 carbs rebuilt with new floats/Pins/Gaskets/the works.


The mechanic that rebuilt my carbs said he tested the charging system voltage and said it's jumping around a lot which leads him to believe it's either the stator or power pack, and usually you should change both at the same time. This is a back yard mechanic that I was referred to with 32 years experience. I already had words with him after I spent 400 dollars and the same problem is still there.

Does anyone have anything to add, or share with me? Anything I might try to avoid buying both stator and power pack. I would think there is a way to diagnose the problem to only one vs spending a lot more money on something I don't even need. Like buying and replacing only the stator, and not buying the power pack. Or do they go hand and in hand if you buy one it's a good idea to get the other?

The boat starts right up and idle's perfectly. So I explained this to the mechanic and he only has the ability to run the motor off of a garden hose. He doesn't have a tank to test the engine under load. I told him this problem doesn't happen on the garden hose only in the water. He told me he could diagnose and fix it no matter what. That is when I drove 100 miles to this guy and left my boat, drove home and came back 3 days later with a absurd bill and the same persistant problem.

So I seem to be venting to you all and not really saying the issue, the boat starts up and I put it in gear and then give it some gas and it hesitates, if I continue to give it gas it will die, if I back off it will stay running. Then I have to push forward a pull back on the throttle until it catches and takes off. Once it takes off it will accelerate and run extremely well I can pull the throttle back and put it in neutral then accelerate again over and over without any problems. But if I turn the motor off and go to give it gas again the problem will happen again usually, sometimes it will be ok. It's a really annoying issue.

It's to the point, I don't even want to bring my kids out on the boat. Might end up stranded.

HELP PLEASE? Anybody?

 

[Daviet]

Re: 1984 70hp Evinrude stalling on acceleration

What plugs are you running?
Is the timer base moving freely when you advance the throttle?
Does it help if you constantly pump the primer bulb?

 

[daselbee]

Re: 1984 70hp Evinrude stalling on acceleration

Launch the boat, get out to where you can test it...and as you accelerate (or try to) push the key in to add gas. If you can get it to go by pushing the key in, then the low speed idle circuits in the carbs are clogged.

I will give you a story....I launched my boat, hard to start, bogged and stalled on acceleration, absolutely refused to believe it was carbs, but in testing, I pushed the key in while trying to accelerate. It responded, but slightly. As I was pressing the control forward, I kept hitting the key, and very soon the engine was up to speed on the high speed carb fuel circuits. It ran fine at higher RPM.
Got home, pulled the carbs, and found what I believe to be salt deposits in the tiny micro holes that provide fuel at idle and midrange.
Every carb (6) was clogged in some manner, some more than others.
Couldn't believe it. Cleaned carbs again (and I do know how to do it) and engine runs fine.

The next thing i would look at is the timing pickup. If you don't have enough advance when the throttle plate begin to open, it will bog.
That is corrected by a proper link and sync. For a test, you can adjust your pickup point (on the water, on the same trip) to allow the timer base to rotate just a bit more before the carbs begin to open. You will have to figure out the exact adjustment point...I don't know your motor so cannot advise on that specifically. It will be very simple and obvious.....the roller that opens the carbs will need to be moved ever so slightly. It will probably have a cam with a mark on it that should be aligned with the roller...look for something like that on the linkage that has an adjustment. Note where it is, move it, test, and put it back if necessary.

All this can be done for free, and the results will tell you something.

Then, you should test the spark quality. Plenty of threads on here about testing spark. You will have to buy ($10 bucks) an adjustable spark tester, and follow the instructions that you find by searching this forum. It is a pretty easy test.
If you want to get deeper into the ignition system, you will need more expensive tools....a DVA meter for measuring the actual ignition voltages.

Please post back with any concrete results you get.

 

[tommyarmour]

Re: 1984 70hp Evinrude stalling on acceleration

What plugs are you running?
Is the timer base moving freely when you advance the throttle?
Does it help if you constantly pump the primer bulb?

I'm using Champion QL77JC4
The Timer Base is moving freely when I advance the throttle
It doesn't help squeezing the primer bulb while giving it throttle.

 

[tommyarmour]

Re: 1984 70hp Evinrude stalling on acceleration

Launch the boat, get out to where you can test it...and as you accelerate (or try to) push the key in to add gas. If you can get it to go by pushing the key in, then the low speed idle circuits in the carbs are clogged.

I will give you a story....I launched my boat, hard to start, bogged and stalled on acceleration, absolutely refused to believe it was carbs, but in testing, I pushed the key in while trying to accelerate. It responded, but slightly. As I was pressing the control forward, I kept hitting the key, and very soon the engine was up to speed on the high speed carb fuel circuits. It ran fine at higher RPM.
Got home, pulled the carbs, and found what I believe to be salt deposits in the tiny micro holes that provide fuel at idle and midrange.
Every carb (6) was clogged in some manner, some more than others.
Couldn't believe it. Cleaned carbs again (and I do know how to do it) and engine runs fine.

The next thing i would look at is the timing pickup. If you don't have enough advance when the throttle plate begin to open, it will bog.
That is corrected by a proper link and sync. For a test, you can adjust your pickup point (on the water, on the same trip) to allow the timer base to rotate just a bit more before the carbs begin to open. You will have to figure out the exact adjustment point...I don't know your motor so cannot advise on that specifically. It will be very simple and obvious.....the roller that opens the carbs will need to be moved ever so slightly. It will probably have a cam with a mark on it that should be aligned with the roller...look for something like that on the linkage that has an adjustment. Note where it is, move it, test, and put it back if necessary.

All this can be done for free, and the results will tell you something.

Then, you should test the spark quality. Plenty of threads on here about testing spark. You will have to buy ($10 bucks) an adjustable spark tester, and follow the instructions that you find by searching this forum. It is a pretty easy test.
If you want to get deeper into the ignition system, you will need more expensive tools....a DVA meter for measuring the actual ignition voltages.

Please post back with any concrete results you get.

I talked with the mechanic that rebuilt my carbs last night. Every component of the carbs have been cleaned or changed and the carbs were actually in a solvent tank for 30 hours. I am pretty upset at the guy but he does know how to rebuild carbs. But what it all comes down to I believe is he tested voltages by the power pack and rectifier and noticed they were real sporadic he said they are normally steady. So he called me last night and actually talked to me for like 20 minutes. He feels certain it's the stator and or Power Pack. He explained the problem will be worse while under load/in the water. He said just remember electricity runs in a circle and what effects the stator, will effect the power pack, and rectifier. I said can't you be more specific like test just the stator so I don't have to buy a power pack and a stator and he more or less said that is the only way he tests voltages.

I feel very confident, I am getting good spark with my new spark plugs I gapped them myself. I feel pretty confident the gas is perfect. Non ethanol 50/1 mixture with Evinrude/Johnson oil. I feel confident the carbs are working perfectly. New gas tank, new primer bulb pumping up rock hard. This guy adjusted the throttle and said the timing was perfect. I mean you can start this engine up first turn of the key you can go to the motor and rev it up really hard and its flawless runs perfect.

I tried the key trick pushing in on the key while giving it gas that is what told me the carbs were having a problem in the first place. You could hear this Phoooooooosh after the carbs were rebuilt that problem is non existent. I tried again pushing the key in while giving it gas yesterday it would not stop the stalling.

I am going to bring a friend out with me on Sunday and have them squeeze that bulb while I give it gas. It's not possible to give it throttle and squeeze the bulb in my boat. I did it before the carb rebuilt and it didn't help.

Anyway let me look back over what you wrote, thank you guys you are really a valuable commodity. THANK YOU

 

[tommyarmour]

Re: 1984 70hp Evinrude stalling on acceleration

This is a video of how the boat was running before all the work I had this week.

http://www.youtube.com/watch?v=-99irHGG8Bk

 

[patrick4266]

Re: 1984 70hp Evinrude stalling on acceleration

I've had that problem on several 70 hp rudes and every time it was the lync and sync. Not saying thats your problem but it probaly is.

 

[tommyarmour]

Re: 1984 70hp Evinrude stalling on acceleration

I've had that problem on several 70 hp rudes and every time it was the lync and sync. Not saying thats your problem but it probaly is.

Link and sync? Can you explain how to fix that.

 

[tommyarmour]

Re: 1984 70hp Evinrude stalling on acceleration

I've had that problem on several 70 hp rudes and every time it was the lync and sync. Not saying thats your problem but it probaly is.

I found this with a google search.


When the throttle/shift control is advanced, 3 things happen. The motor shifts into gear first; second, the timer base starts its advance, then the throttle valves start to open. It's critical that the spark advance begin before opening the throttles, else the motor loads up on fuel and falls flat on its face.

Here's a couple pics, the first is a scan from an early-70's manual, the second is a photo with more of the parts identified -- it's mid-80's motor but the parts are pretty much the same as yours.

http://i521.photobucket.com/albums/w333/…

http://i521.photobucket.com/albums/w333/…

first make sure the throttle lever & cam yoke are the specified 4 31/32 inches apart as in the first pic.

Then take the airbox cover off and make sure that all three throttle butterfles are closed at idle and parallel thoughout their range of motion. Adjust the WOT stop screw if needed to be sure they end up perfectly horizontal (not beyond) at WOT.

Use the idle set screw to set the idle at about 950 RPM with the motor idling in neutral (lower unit submerged). Set it at around 1100 with the motor running on muffs -- backpressure on the underwater exhaust drops it by a couple hundred -- you have to fine-tune it at the lake.

There's a thumbwheel on the throttle cable just inside the cowling; adjust to where the throttle lever moves between the Idle & WOT stop screws, with neither of those so far in, or so far out that there's no room for fine tuning.

You need to make sure that the motor shifts into gear *before* the throttle lever moves the timer base, which increases RPMs.

This is the crucial part: the throttle cam has to hit the cam follower roller right on the mark. You can see a screw in a slot just below the roller -- that lets you move the roller forward or back to line it up with the mark on the cam.

 

[tommyarmour]

Re: 1984 70hp Evinrude stalling on acceleration

I noticed two slots on my cam. There is the top slot and it says "Start" beside it. Then I have the bottom slot. The Engine is not running and the roller is on the bottom slot. Is this normal? Should the roller be sitting on the start slot or the second slot when the engine is off and just sitting.

 

[tommyarmour]

Re: 1984 70hp Evinrude stalling on acceleration

Question, If my battery were getting old what kind's of problems would I run into? Could a bad battery cause issues with rectifier, stator, or power pack?

 

[Bunker]

Re: 1984 70hp Evinrude stalling on acceleration

I have had this prob. For about a year now and it turned out to be the lineage sinc. Mine was sticking and just needed lubed up on used.

 

[tommyarmour]

Re: 1984 70hp Evinrude stalling on acceleration

I have had this prob. For about a year now and it turned out to be the lineage sinc. Mine was sticking and just needed lubed up on used.

Can you explain exactly what you mean?

 

[tommyarmour]

Re: 1984 70hp Evinrude stalling on acceleration

2 days ago I brought the boat out and as long as I just gradually gave it gas it was able to accelerate normally 9 out of 10 times. Which is truly a miracle.

http://www.youtube.com/watch?v=h5eXZMy5RFw

This is a closer look at it, today when I was checking link and sync. I'm thinking whatever problem it had probably link and sync is so close that I am afraid of loosening that roller ball screw and messing it up worse.

http://youtu.be/5Gkau7hoc3w

 

[Bunker]

Re: 1984 70hp Evinrude stalling on acceleration

Move your throttle back and forth you will see the control arm moving. The brass shaft that moves in and out is what you want to lube. Hope this helps.

 

[78 mckee]

Re: 1984 70hp Evinrude stalling on acceleration

Check the wires from the timer base. The wires flex as the throttle is advanced and the timer base moves to advance the timing. Those wires can break inside the insulation over time and can cause the kind of intermittent shut-down that you are experiencing. The wires can also rub on sharp edges and then short to ground in a certain throttle position and have the same effect.

 

[Blacksting]

Re: 1984 70hp Evinrude stalling on acceleration

Got home, pulled the carbs, and found what I believe to be salt deposits in the tiny micro holes that provide fuel at idle and midrange.


got into a discussion about bad gas and this guy tells me that ethonal is eating away aluminum gas tanks and the 'white' deposits are getting into the fuel system . ,..........could the 'salt' be corrosion of aluminum ?