"Crash Course" in Idle Mixture and Idle speed and distributor stuff? (1 Viewer)

Joined
Apr 16, 2007
Messages
175
Location
Jacksonville, FL
With photos, maybe?

My 40 is stalling out every now and then and I have to keep my choke pulled slightly even at running temps (160-170) or it will stall a little bit, or run kinda rough. I replaced the fuel filter and it still skips a beat sometimes and "coughs" (hiccups? I dunno) Basically it loses power for a bit.. Imagine pulling your foot off the gas and stomping back down on it immediately.

Is it running too rich? My "comfortable" idle speed is around 1k-1200rpm. It stalls ocassionally if it's less than that. When i adjust the choke it takes a couple seconds or so before it reacts, and sometimes it flip flops a little bit between a lower and higher idle speed.


Any ideas?
 
Joined
Sep 6, 2009
Messages
1,046
Location
Spokane,Wa
Have you checked:

1 plugs
2 plug wires
3 timing, with a timing light
4 vacuum leaks
5 battery voltage
6 points (if you have them)
7 tappet noise
8 gas tank vent
9 carb base bolts tight
10 Are you out of beer
 
Joined
Apr 16, 2007
Messages
175
Location
Jacksonville, FL
1 plugs - No
2 plug wires - They seem intact ;p
3 timing, with a timing light - I don't know what that is
4 vacuum leaks - I don't know how to
5 battery voltage - Voltage seems good
6 points (if you have them) - Don't know what that is
7 tappet noise - Don't know what this is
8 gas tank vent - Cap is on tight (?)
9 carb base bolts tight - No
10 Are you out of beer - Yes
 
Joined
Sep 6, 2009
Messages
1,046
Location
Spokane,Wa
OK, good enough except for #10. Screw the air mixture screw in until the engine starts to run rough, back the screw out until the engine runs smooth. Good. Count the number of turns( half turns), it would be nice to know where you were.
 

piecemeal

SILVER Star
Joined
Nov 18, 2008
Messages
1,101
Location
Hellertown, PA
x2 on the tappet noise.... what is that?? Mine does make a ticking sounds (when it runs, whiCh isn't often b/c something is wrong).
 
Joined
Sep 6, 2009
Messages
1,046
Location
Spokane,Wa
This would be a tapping sound coming from the valve cover. There is another post going on called valve clearances. Check that out. Valve adjustment and tappet adjustment are the same thing. Tappet is kind of old school, back when they tapped alot more.
 
Joined
Apr 16, 2007
Messages
175
Location
Jacksonville, FL
Mine taps. Well it kind of sounds like a diesel engine when it's running. But that is any Land Cruiser I have ever been in.
 
Joined
Feb 6, 2002
Messages
15,272
Location
OC, CA
Any ideas?



If it won't idle at 650 RPM, then either it is getting too much air or not enough fuel at idle.
Check:

1. Idle fuel cut off solenoid operation. It should click when the key is turned on. If it clicks, try turning out the idle mixture screw a couple of turns CCW.

2. Check for manifold vacuum leaks. Rund the engine at as low a speed as it will run at. Spray carb cleaner or propane gas around all the connections to the mainifold. The engine will speed up when you spray if there is a leak in the vicinity.
 
Joined
Jan 3, 2003
Messages
7,184
Location
McCall, ID
2. Check for manifold vacuum leaks. Rund the engine at as low a speed as it will run at. Spray carb cleaner or propane gas around all the connections to the mainifold. The engine will speed up when you spray if there is a leak in the vicinity.

I thought the engine slowed down when you spray propane? Maybe it depends?
 
Joined
Feb 6, 2002
Messages
15,272
Location
OC, CA
It would slow if you sprayed an inert gas, like CO2, nitrogen, argon or even water. If it burns, like propane, it will speed up if the idle mix is lean due to a vacuum leak.
 
Joined
Jan 3, 2003
Messages
7,184
Location
McCall, ID
It would slow if you sprayed an inert gas, like CO2, nitrogen, argon or even water. If it burns, like propane, it will speed up if the idle mix is lean due to a vacuum leak.

OK. Makes sense. I have heard that propane is better than carb cleaner because it is easier for the molecules to get sucked in around a leaking manifold gasket. Has that been your experience?
 

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