1967 Evinrude 9.5 Throttle Deviations

[smancuso]

This motor starts and runs and looks great, but, when I advance the throttle in gear or neutral (motor is attached in a barrel of water) speed increases and then after 10-20 seconds returns to idle speed. Holding the throttle wide open, the speed will gradually increase then slow down again. I have set and reset idle adjustment, set points, cleaned carb 3 times, taken apart the fuel pump, cleaned the plugs and reset gaps and now I don't know what.
Many thanks for suggestions.

 

[tashasdaddy]

Re: 1967 Evinrude 9.5 Throttle Deviations

read ethanol, also look for air leaks, http://forums.iboats.com/showthread.php?t=344598 it actually sounds like you need to adjust float needle, opening late, not providing fuel soon enough.

 

[smancuso]

Re: 1967 Evinrude 9.5 Throttle Deviations

Thank you for advice. I spent a few hours cleaning and re-cleaning and checking lines and tightening connectors. Mostly I tried adjusting float to open sooner, using mfr recommendations of 13/16" and 1-7/16". It was 1/8" lower to begin with in both open and closed positions.
At these proper settings no fuel flowed at all. I removed and replaced carb 8 times overall trying to figure this out. Finally I reset float to the lower settings where I had found it and the motor ran and revved and I was able to adjust low speed idle as per your instructions.
One hour later I re-started the motor and it had slipped into it's old habits again, that is, upon increasing throttle the speed increases for a few seconds and then goes to idle speed while the throttle is held wide open.
At this point I would appreciate a call for divine intervention! Thanks.
Sam

 

[Rick.]

Re: 1967 Evinrude 9.5 Throttle Deviations

In your new kit did you install/get the little clip that attaches the float needle to the float arm? It sort of sounds like a flow problem for sure. Did you remove the high speed jet from the bottom of the carb. and clean that passage real good? It sonds as though you high speed passage is completely blocked. Your on the right track suspecting the carb. I think. Best of luck. Rick.

 

[smancuso]

Re: 1967 Evinrude 9.5 Throttle Deviations

Deviations have come and gone. Still operating out of a barrel.
Last three or four starts during past few weeks motor ran great; excellent response to throttling up.Yesterday I demonstrated how well it ran for a friend and the problem returned! Exactly the same. Starting is fine, idle is fine, but throttle up and motor surges briefly and then runs slowly with an occasional, half hearted surge. Much to my chargin.
Here is what happened next: friend raised the motor cover and speed increased. Cover down and speed decreased (throttle wide open)
This continued and was eerie. I thought the kill switch was being shorted somehow and replaced it. No change.
Could air intake be restricted? How does air get into carb?

 

[crxess]

Re: 1967 Evinrude 9.5 Throttle Deviations

You have same year 9.5 as mine. Air enters through 2 front slots in the control plate area.
Exhaust leak at base of motor or exhaust cover area. With cover on, exhaust is entering carb and choking motor. needs to be located and corrected or it will get worse.
Do not run on boat without cover - fire hazard
I assume you are revving to full throttle IN GEAR as this motor has a neutral lock out to prevent revving in neutral.

If bypassed and revving in neutral - STOP before you damage motor from a runaway.

 

[Rick.]

Re: 1967 Evinrude 9.5 Throttle Deviations

What your experiencing is rather common with the 9.5. It sits low to the barrel and sucks in exhaust even if you don't have an exhaust leak. You can set a fan up beside the cowl and run it with the fan going or ( and what I think is best) take it to the lake and I'm fairly sure it will be just fine in the great outdoors. If not then start looking for an exhaust problem entering straight into the cowling. If you look there doesn't seem to be much combustion air openings but I assure you there is enough to run at WOT. Rick.

 

[smancuso]

Re: 1967 Evinrude 9.5 Throttle Deviations

Dear friends,

Many thanks for excellent advice. Believe me I took it. Getting the motor out of the barrel and into the lake worked. Throttle problems were a result of sucking in the exhaust, confined in the stupid barrel. I also learned a lot about this motor.

Now for the story of the "Sea Trials." Lets just say that our excursions into the lake were very short. Motor shifted ok but in forward gear when I cranked it up, something slipped. We tried again and again to throttle up but,
although the motor ran fine, well, something slipped. It felt like the time the clutch wore out on my vw van. Low speeds ok but rev it up and she slipped.

Did not discuss this before but I have already removed the lower section, cleaned up water pump, impeller etc. Then inspected gear case which had decent looking oil. Although I do not totally understand the mechanism I can say that gears, yoke and gizmos looked good. No obvious, or excessive wear.
Got it re-assembled, added new oil and here we are. Slippage. By the way, drive pin, propeller and hub also went back together ok.

Any thing I can test or try to figure out on my own (with sage advice, of course) is how I will proceed before, well, you know, spending a bundle on an old motor! Many Thanks,
Sam

 

[ezeke]

Re: 1967 Evinrude 9.5 Throttle Deviations

Though it may not be apparent, your propeller has a rubber grommet between the inner and outer sections of the hub, which may slip. This is designed to release when you strike an underwater object, but age will sometimes break them down.

It is also necessary that the connector that holds the two sections of the shift rod be properly connected; the screws must be removed in order to hold the beveled area of the shift rods.

 

[Rick.]

Re: 1967 Evinrude 9.5 Throttle Deviations

If your saying your motor revved full out but something was slipping then it may well be your prop. Remove it and draw a line across the diameter from edge to edge. Put it back on and take it out on the water. Next time you experience the slipping, remove the prop and see if the lines still match. If they don't you have a slipping prop and need to have it repaired or replaced. If the gear case is slipping in and out of gear, and it could be, you sill notice an almost violent banging as though you hit a submerged stump. Don't despair your getting closer to having a functioning engine. Rick.

 

[Mandrake35]

Re: 1967 Evinrude 9.5 Throttle Deviations

Is it popping out of gear? It may be that when you put the shift linkage back together....you didn't put the rod far enough into the brass coupler. Alternatively the adjustments for the shifter under the cowl may be out of whack. does it run fine in reverse? Hope this helps.....sounds like you're close to sportwin cruising.

 

[crxess]

Re: 1967 Evinrude 9.5 Throttle Deviations

If it is snapping neat ls into reverse and forward (Locking in), and you hear no gear chatter. you probably have a bad prop hub.(Slipping)

The hub sits in a rubber insert that is all pressed into the prop. It is designed to fail first if the prop takes a hard hit.(Rock or Bottom strike)

Remove prop. mark a line on the back side. center to edge. install and duplicate the problem. Remove prop and look at the line. If it is now (2) lines the prop needs rebuilt.

This is why I carry spare props for all my boats.

 

[smancuso]

Re: 1967 Evinrude 9.5 Throttle Deviations

Thank you all,

I changed the prop although it is another old one, from a similar motor.
This one seemed to fit tighter. Went out for sea trials again. Same result, perhaps a bit worse; slippage. Back to the shop.

Made the attempt to put some home made torque on the prop by wrapping it in a bundle of line, removing the nut, threading on two metal nuts that would lock together without touching the prop hub and cranking down on the nuts. All the while in neutral. Pretty much just made a mess and got no conclusions. If I buy a new prop and that is not the problem, it's a waste. Can props be rebuilt? Would a dealer do so or make arrangements? Is there a way to test at the backyard boatyard?

The way out is to throw money at this, but no gratification.

Your student,
S

 

[crxess]

Re: 1967 Evinrude 9.5 Throttle Deviations

Well......... if the hub is really slipping bad, you can place it in gear and step on the blade. the prop will turn without turning the motor over. Kind of hard to do on a smaller motor.

Marking a line with a magic marker is the easiest way to test and tell.

Your local marine supplier can probably send teh prop out for you. He will undoubtedly take his cut for the effort.

Or give these people a call http://www.propmd.com/

 

[smancuso]

Re: 1967 Evinrude 9.5 Throttle Deviations

5th sea trial, Sept 16.
Found a local prop shop who replaced the hub on my prop in one day.
Put it back on the motor and out to the canal we went.
Pretty much the same problem; at low speeds the boat moves fine but at WOT the motor gets the hesitation blues and will not plane the boat. About half throttle is a smooth, slow ride. We put it in neutral and the motor revs great. instant response.
This motor is shaky, that is if you grab the lower unit you can move it back and forth a half inch or so. Friend thinks this and or gear box is problem but I say it is ignition. There is no clunking when shifting and the shaking is probably worn mounts. Probably.
Once I get a smooth ride at WOT I will be willing to address other issues.
Anyway, it ain't the prop.
Clues?
Sam

 

[crxess]

Re: 1967 Evinrude 9.5 Throttle Deviations

Got it re-assembled, added new oil and here we are. Slippage. By the way, drive pin, propeller and hub also went back together ok.

I changed the prop although it is another old one, from a similar motor.
This one seemed to fit tighter. Went out for sea trials again. Same result, perhaps a bit worse; slippage. Back to the shop.

Pretty much the same problem; at low speeds the boat moves fine but at WOT the motor gets the hesitation blues and will not plane the boat. About half throttle is a smooth, slow ride. We put it in neutral and the motor revs great. instant response.

This motor is shaky, that is if you grab the lower unit you can move it back and forth a half inch or so. Friend thinks this and or gear box is problem but I say it is ignition. There is no clunking when shifting and the shaking is probably worn mounts. Probably.

Complex array of mis-information and multiple problems.

Last one first: Very probably worn out mounts. Stretchy or even broken. You need to access and visually inspect all.

Next, if your last statement is what you have been experiencing all along, you never had prop slip or slippage as you originally said.

If you have a high speed miss there could be several reasons:
Timing issue from worn or improperly adjusted parts.
Plugs failing.
Carb issue.
Fuel pump weak.
Air leak in fuel system.

even with all working correctly there are other considerations that can keep the boat from reaching plane speed.
Hull design
Total load
load distribution
Prop pitch.

 

[ezeke]

Re: 1967 Evinrude 9.5 Throttle Deviations

Even under the best conditions the motor will move within the outer exhaust housing by design; it is built that way, suspended on several rubber mounts.

There are propellers of various pitch which can produce better results if you are having trouble getting on plane. The lowest pitch will give the highest thrust and get you out of the hole quicker, but may limit your top end.

The lowest OEM prop is 0386587 with 5 pitch and very hard to find.
Next is a Michigan Wheel 012068 at 6.5 pitch.

Original picture from Iwombat, edited by me.