454 Carb Help, URGENT-We're on the road...

[gypsychris]

Hi all,
1st let me apologize for being absent for so long--since bozeman, we've had lots of things going on...redid our brakes etc... anyhow.. we finally have a web connection, here outside Yellowstone.
(we've also added lots of feedback and thoughts about Bozeman and the great people we met there...check out posts on our Blog, Liz did most of the writting..) OK back to business:
Here in the high areas, above 5000 feet, seems our 454 is having troubles when we fire her up:
IT revs fine, execpt seems that the choke remains on, and when we try to pull out..the engine dies, as if the fuel is not burning... after numerous tries and letting it run for a long time, we are fine (ie I can shut the engine off, and fire her up right again, and ddrive away without a problem...)
Thus far, we've been told:
a) Altitude is the problem
b) The choke might be stuck
c) We should/can actually wire the choke to be open (to let the necessary air in) via a wire etc...

what do you guys think?

I may not be able to have web access for a while.... so feel free to call me and discuss: 646-573-9780 (you might want to leave a voicemail...) I really appreciate it.

Thanks, and see you all down the road !!


Chris

[mustang]

What year is your unit? The reason I ask is the accelerator pump on top of the carb may be bad. There are a few things to easily trouble shoot. 1 st when the unit is having trouble (symptoms) imediately while accelerating look out at the tail pipe if it blowing black then you are dumping fuel or getting to much. If not When you press the peddle if the RPMs seem slugish or drop then when released if comes back that is a fuel delivery issue. Clogged filter bad accellerator pump or fuel pump that is delivering pressure but not volume. If it is blowing black either your choke is stuck on or you gat a peice of debri in your float bowl. which could fowl spark plugs down the road and create a bigger headache. Good luck on this. Keep in mind ignition is close to fuel when symptom arise A weak coil can do the same thing. If you are mechanical you can look down the carb throat work linkage while engine is off you should see a steady stream of fuel if not accel pump is bad. Good luck

[richinny]

while you're checking things, remove the distributor cap and rotor and look at the underside of the rotor for any burn marks or a pinhole in the center of the rotor.

[overlander63]

If it is the choke not opening, it is not the altitude. It MAY be that it is cooler where you are now, and the choke may be closing to a point it normally doesn't close to in New York. There is a procedure for checking the initial choke opening when cold, but it does involve a feeler gauge to check.
When the truck is cold, remove the air cleaner, and depress the gas pedal fully. Then try to insert a (I think it's .012", it's been a long time since I messed with carbs) feeler gauge into the top edge of the butterfly. If it won't go in easily, you need to loosen the screws holding the choke thermostat in place, and rotate the choke thermostat until the feeler gauge slides in and out of the butterfly while just barely touching the butterfly and edge of the carb.
Another item that may be giving you problems is the choke stove. Depending on model, it is either a small metal pipe that goes from the intake manifold almost directly under the choke stove, or an electric wire that feeds electricity to the spring in the choke thermostat. The current warms the spring, causing it to expand and open the choke.
If the truck starts fine, but after a minute of running starts running rough, and billowing black smoke out the tailpipe, it may be the choke pulloff. This is a vacuum operated piece that pulls the butterfly open a little more after the engine starts.

[mustang]

If the choke is stuck it would be running rich ( The Black Smoke ) I guess I should also ask does your unit have pony pump back by the tank to push the fuel up? I have seen alot of units with them for high altitude or mountain climbing when fuel draw and volume is needed

[deltatango]

It is cold and the choke is closing. Couple that with some altitude and you have an engine that is too rich.

Solution: Disconnect the choke. Wire it open with a paper clip or what ever.
Or take the linkage going to the stove
on the manifold loose.

Without the choke it will be hard to start when its cold. Use gas petal to pump extra gas until it warms up.

Get it fixed when you get somewhere.