1971 4HP (4106D) Won't idle

[canadian_fisher]

Got this little kicker from a friend in the family.
Before the repairs, motor would only run 2-3 seconds before dying out.

Changed the Fuel pump, cleaned and installed carb kit.
I can now get the motor to start in WOT, but won't sit down and idle w/o shutting down. Also, it only runs about 30-seconds then shuts down.

Question: The throttle cam seems to be a little warn-out. How serious is this to my non-idle issue?
How tight is the Synch-spec of these little outboards?

Any feedback is appreciated.
CF

 

[Paul Moir]

Re: 1971 4HP (4106D) Won't idle

A little wear is normal. Won't affect a thing. If the sync is way out then midrange will be bad but it won't affect full throttle at all. You should also be able to get the engine to start at about 1/2 throttle or a little less.

Does pumping the primer bulb keep it from dying? Does it affect anything?

How's spark? Can it jump 1/4-3/8" gap?

Compression?

Finally, did you remove the core plug from the top of the carburetor and clean the idle orifice directly? Did the carb kit come with a new plug?

How does the engine respond to the carburetor adjustments?

Is it overheating? If you drop a drop of water onto the top of the head (where the spark plugs screw in), does it sizzle

Sorry for the 20 questions routine, but we need to know where you're at.

 

[canadian_fisher]

Re: 1971 4HP (4106D) Won't idle

Hi Paul.
I like 20 questions........ it helps me think clearer.

-Primer bulb does help. Fuel pump is working (tested).
-Spark is bright blue, but I'll check the gap tonight.
-Compression is 125PSI on both.
-NO, I didn't know how it get the CORE plug off, but the carburetor was very CLEAN amazingly.
-Engine only responds to High speed not Idle adjustments.
-No idea about over heating..... I'll check tonight.

Keep those questions coming.......
Thanks. CF

 

[iwombat]

Re: 1971 4HP (4106D) Won't idle

If pumping the primer bulb helps, then it's a fuel delivery problem. Did you vent the tank properly?

 

[canadian_fisher]

Re: 1971 4HP (4106D) Won't idle

Sorry type-O, pump does NOT help.......
Yes, cap is competely OFF the tank.

CF

 

[iwombat]

Re: 1971 4HP (4106D) Won't idle

In that case, I'd try adjusting the float. The problem is someplace from the carb float back.

 

[iwombat]

Re: 1971 4HP (4106D) Won't idle

FWIW I think you've got two problems going. First, is the fuel delivery issue. Second, is the idle issue. Probably best to pick on the fuel delivery problem first.

 

[iwombat]

Re: 1971 4HP (4106D) Won't idle

Just occured to me to check the fuel hose. Is it a new hose? Some/most/all (?) hoses have an in-line filter. Probably easier to check than the float level.

 

[Paul Moir]

Re: 1971 4HP (4106D) Won't idle

If pumping the primer does not help with the 30 second stopping problem, it's got to be either overheating or running too rich. Running rich would also cause serious idle problems. Are the spark plugs soaked with fuel after running?

(pumping the primer while running rules out bad hoses, air leaks previous to the fuel pump, fuel pump, tank pickup screen, and leaking float needle)

 

[iwombat]

Re: 1971 4HP (4106D) Won't idle

Oh, wait I totally skipped over your follow-up post - It's been one of those days.

Pump does NOT help. - DOH!

In that case nevermind my suggestions.
It's gotta be from the float back it it's fuel related. i.e. jets, choke plates, linkage etc.
Or something like an overheating problem.

Just clarifying I've got no disagreement with Paul on this.

 

[Paul Moir]

Re: 1971 4HP (4106D) Won't idle

Got me too. Good thing there's the edit button.

 

[canadian_fisher]

Re: 1971 4HP (4106D) Won't idle

This is great, I appreciate the enthusiasm!!
Here's the update.....

Got the outboard run WOT in a barrel for 2-3 minutes until it was good and hot.
Adjusted the High-speed jet until running smooth.
Head is definatley NOT overheating.
Disassembled rebuilt carb, verified float level OK.
Removed the Core plug and verified idle orfices OK.
Verified that all idle passages were clean and clear.
Fuel lines from tank to carb are new and tie-wrapped.
Motor would only idle if I used Choke as the throttle.

I also noticed a healthy screwdriver mark very close to the idle-fuel pickup on the base of the carburetor.
It was so close, that I believe that gas is leaking out.
I filled the mark (not the hole) with Liquid Metal, let it sit and installed bowl gasket again.

I'll be firing this up again tonight hoping for a better result.

Any other ideas?

CF

 

[Paul Moir]

Re: 1971 4HP (4106D) Won't idle

Glad to hear you got that 30 second business taken care of. Must have been the high speed adjusted too rich.

Although there are several possible causes for a lean idle (as the choking indicates), there's only one likely one: the carburetor. Something, somewhere must be blocking the idle passage. Follow it from the bowl all the way up through the low speed mixture needle. Make sure there's no obstructions where it goes through the carburetor gasket. Make sure the carburetor gasket's idle passage hole is in the correct spot.

How far off are you on the link & sync? If you've got the seloc manual, have a look here as their instructions are extremely confusing:

Click here

 

[canadian_fisher]

Re: 1971 4HP (4106D) Won't idle

Hi Paul.

Well the saga continues.
I tore the carb apart again and had a look-see.
All the Idle ports are clean and clear.
Float seems OK.

As for Link and Sync, the follower was warn down about 1-2mm deep, but I put some tape around to fill the wear, so that wasn't the problem.

Took the plung, and popped off the flywheel to examine the points and Ignition coils.......
Points are looking pretty good and well adjusted.
The coils are looking pretty SICK. The insulation is heavily cracked with white corrosion emitting from them.
Next job will be to replace the TWO coils.......

That would explain why the motor would "cut out" rather than "die out" when backing off WOT.

Thanks CF.

 

[iwombat]

Re: 1971 4HP (4106D) Won't idle

Yep, there's your problem right there. Make sure the plug wire ends are nice and clean (as in not frayed) and the insulation is good while you're in there.

 

[canadian_fisher]

Re: 1971 4HP (4106D) Won't idle

What does cracked insulation on the coils cause?
My thought was arching to the flywheel.

CF

 

[Paul Moir]

Re: 1971 4HP (4106D) Won't idle

It'll arc anywhere, usually to the armature plate which is in very close proximity.

The thing is, the breakdown voltage of the fuel/air charge in the cylinder varies with the pressure, so when spark is happening at TDC the breakdown voltage is highest. What that means on the 4hp is, that ignition is working it's hardest right around 1/3 throttle - just where you set it for starting.

The reason for the 1/4" - 3/8" gap spark test is to simulate those conditions. If the ignition coils are cracked, it'll arc through them to ground rather than jump that kind of gap.

Have a good look at your wires when you do the coils. If the insulation on them is cracked, pick up some wire as well. You must use metal core wire, not automotive carbon core wire.

 

[canadian_fisher]

Re: 1971 4HP (4106D) Won't idle

Good advise Paul.

BTW: I now know what you mean about the gap spark test. I would always get spark from the plug when grounded, but never from the gap tester at 1/4" or more........
It never maked sense until just now.

Cheers....... CF

 

[canadian_fisher]

Re: 1971 4HP (4106D) Won't idle

SUCCESS !!!!!!!!!!!

Yup..... two heavily cracked Ingition Coils were shorting to the frame at low RPMs.
I even cut them open to see the burn marks.
The 4HP starts up with a 6-inch pull on the cord.
I almost shed a tear when I call my Father with the good news d8)
At least now I have a newly rebuilt ignition and fuel system.

Thanks to Paul Moir, and iwombat.
CF