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Stalling

rich_p

Regular Contributor
"I have '86 or '87 454

"I have '86 or '87 454's and one will not idle after being run hard. After crusing when I bring back to idle it will run rough and stall. It will then be hard to restart but if I let it sit for about 5 minuites it will start fine, but still stall when manuvering. I am suspecting a faulty coil, but am open to other suggestions."
 
"coil, leaking distributor cap

"coil, leaking distributor cap, bad plug wire(s), bad advance mechanism, worn out breaker points, intermittant ballast resistor.

you could switch coils between engines and see if the issue follows the coil."
 
I have a new Accel super coil

I have a new Accel super coil as a spare that I will be swapping out later. The cap looked clean (no signs of arcing) but I am thinking of changing the dual points setup to electronic in the near future.
 
"So, it works at med and high

"So, it works at med and high power settings but not idle? Maybe the idle port(s) in carb are plugged. An occasional WOT test is good for checking almost everything except the idle jets."
 
"It will idle fine when it is

"It will idle fine when it is cold, but after it gets hot it starts to act up."
 
"Have you tried adjusting the

"Have you tried adjusting the idle settings?


Idle is irregular, rough or too low
#
Step 1

Adjust the idle mixture screws in the front bottom of the carburetor. Starting with the driver's side, screw and turn the idle mixture screw in until the RPM begins to drop.
#
Step 2

Turn the screw back out until it reaches its maximum RPM and is no longer climbing. Do the same for the passenger side screw. Repeat the process one more time, making sure that the screw is only turned out enough to reach maximum RPM.
#
Step 3

Adjust the idle screw at the throttle linkage and set the idle at about 650 RPM at idle and in park."
 
"Rich -
you need to determine


"Rich -
you need to determine if the issue is occuring with the choke open or closed. If it is fine with the choke closed - that can mask the clogging Dave was referring to. If that clogging exists, you won't see any mixture control from the idle screws. If its the Q-jet, there are no idle jets - just metering restrictions that will need to be cleaned."
 
"Mark, what is the best method

"Mark, what is the best method for cleaning the idle adjustment passages if the carb is installed and you don't want to remove it? Can you just remove the adjustment screws and blow compressed air in the carb? Or could you damage anything by doing so?"
 
"Well I guess it will have to

"Well I guess it will have to wait until I pull them for the rebuilds I just bought kits for. Guess I better get off my arse and get it done.

The reason I ask is that my starboard engine likes to hesitate and sometimes dies when maneuvering around the docks and shifting from forward to reverse and back. I've been suspecting dirty and or clogged passages in the carb, hence the rebuild kits."
 
"its not the idle adjustment p

"its not the idle adjustment passages where the clogging typically occurs, it is in the metering orifices "upstream" of the mixture adjustments.

Can you damage anything - probably not permanently but you may make an intermittent consistent by wedging a piece of crud into an channel."
 
"Basic question for the idle a

"Basic question for the idle adjustment screws on a Q-jet. Are the adjustment screws metering the amount of air or fuel? Meaning turning them out would richen if they meter fuel, but turning them out would lean if they meter air.

I'm assuming they are metering fuel and not air."
 
"Rule of thumb.
if the adjust


"Rule of thumb.
if the adjustments are
low on the carb = Fuel
high on the carb = Air.
The only thing that we do different from tailspnr, is after we reach max RPM, we then lean out the carbs (screw the needles in) another 50 - 75 RPM.


Fred 156-M"
 
"Not to diminsh Fred's ans

"Not to diminsh Fred's answer, in any manner - the Q-jet mixtures screws change the quantity of the emulsified air-fuel mixture feeding the port below the primary throttle plate. After going past both air bleeds, the mixture surely isn't a liquid anymore."
 
"I absolutely agree.

Trying


"I absolutely agree.

Trying to think back, the only carb that I recall, that may of adjust the air, may have been the old AVS (with the single adjuster screw in the middle, pre AFB) carbs that those old Chryslers had on them.

Fred 156-M"
 
"Re: ""So in a nutshel

"Re: ""So in a nutshell, screwing the adjustments in will "lean" out the motor at idle?""

Yes , sorry

Fred 156-M"
 
"I don't think it is an id

"I don't think it is an idle issue because even if I keep the idle at about 1000 after a high speed run, it will eventually quit.
Checking the choke is a good one. It will run fine up to operating temp but after a high RPM run it acts up. I just finished putting the genset back in (cracked exhaust manifold) and will be opening up the other hatch cover tomorrow.
I'm still leaning towards a weak coil when it gets hot, but the other suggestions will give me some other things to check. Thanks."
 
Well just a quick update on mi

Well just a quick update on mine. I cleaned the inside of the rotor cap (will replace them both this weekend) and richened up the low end idle setting on both carbs. as a result the motors ran so much better at an idle that I was able to lower my idle settings back to 650 rpms (I had previously set a high idle as you to try and eliminate stalling) and it ran great. I took it out of the marina and for a 1 hour cruise and it performed great. Never stalled on me once. I only expect for it to get better once I install the electronic igniotion kits and rebuild the carbs.

I had intented on installing the ignition kits last night but I couldn't read the timing marks on my front pulley using the timing light so I elected not to install until I clean up the marks so I can properly set the timing once installed.

So at least I'm feeling much better about mine......
 
Rich - sounds like you have a

Rich - sounds like you have a plan - keep us posted after your next visit.

Tailspnr - use some 'white-out' to highlight the timing marks; it will aid your visibility a lot.
 
Changed coil and resistor. Did

Changed coil and resistor. Did three hour run and was fine at low idle manuvering afterwards.
 
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