Just put a new rebuilt Motorcraft 2150 on my 79 Bronco, 400. My electric choke is not functional and I have to hold my foot on the gas to keep it running until it starts to warm up. I have the choke hooked up but there is no electricity going to it. Where does the wire go to in the harness after it is pluged into the connector on the firewall? Is there a fuse somewhere for the choke?

 

First the hot wire causes the choke to come off, not on. For stock applications it should come off the firewall on the passenger side. I believe it comes from the alternator so it only goes hot with the engine running and only goes to about 9v.

 

In that case then how do I get the choke to work properly? It doesn't close far enough to keep the engine running while cold. I have to take the air cleaner off and close it more by hand or just hold my foot on the throttle till it warms up. I have the wire plugged into the connector on the firewall but there is no power going through it. I can already tell this truck is going to be a major pain in the winter time without the choke working correctly.

 

There are three screws on the retainer for the black plastic choke coil cover. Lossen them just enough to rotate the cover and the tension on the choke plate will change. It should be just closed on a cool morning. You may have to open the throttle slightly to allow the choke to close while you adjust it.

If you don't get voltage to the unit it will be extremely slow to open if at all. I try to check my wiring diagram.

 

Refer to my writeup on the proper procedure to set choke index and fast idle after a carburetor rebuild. It's a long one, but it'll get it done right.

https://www.ford-trucks.com/forums/7...ml#post6422219

 

Ok, thanks to everybodys help I now have a properly working choke, no more holding the gas waiting for it to warm up, its great, lol. I have one more question, there are two metal tubing lines that go from the passenger side of the manifold to the passenger side of the carb. One of the lines are broke in to, where would I find one and does this affect performance?

Also when I am going at about 40mph and let compltely off the gas it sounds like a manual shift(slight poping back through the exhaust and I can smell fumes). I removed and blocked off the egr valve because I thought it may be leaking or something, It wasent hooked up to the carb though. The port at the spacer plate was plugged off. What could cause the problem?

 

One of the metal lines is a vacuum signal. It connects to the top of the carburetor by a small length of hose. If this is cracked, it will affect performance because it introduces a manifold vacuum leak. The other metal line supplies warm air for the choke. It connects to the choke housing through a flare fitting. if it is cracked, the choke may not get hot enough to open. I don't know of anywhere to purchase these other than to flare and bend a new line yourself.

Popping when you let off the gas usually indicates a manifold vacuum leak.

As a side note, you shouldn't be without an EGR valve. Don't block it off, and it should be connected. Ported vacuum (above the throttle plates) should run from the carbruetor to a ported vacuum switch in a water jacket, and then from the switch to the EGR valve. Motors set up for EGR are engineered differently than their non-EGR predecessors. Removing EGR requires a long trial-and-error tuning process that will, at best, get you to where you started. Anyone that tells you to remove it for "performance" because it is "smog junk" is misinformed and lacks a true understanding of the purpose behind it.

 

I have checked for manifold vacuum leaks by spraying carb cleaner around it while the engine is running, no change in engine idle. Could my problem be from a improperly functioning vacuum advance?

The egr valve has never been hooked up since I owned it so thats why I removed it. The only problem I am having is the one I previously mentioned about slight poping back. Only does it going down the road. If you rev it up in park and let off of it it does not do it. Maybe the broken metal line is causing this that goes to the carb to intake?

Is there any draw back to not having the egr? I have two 79 trucks both have it removed and run fine. I have a friend that also has a 79 Ford with the egr removed and runs fine. So that kind of confuses me.

All the emissions equipment have been removed from both my 79's so I have no idea where everything goes.

 

It's hard to judge the effect that removing EGR will have, because it depends on whether or not your motor is stock. With a factory timing curve and stock jets in the carburetor, you'll often experience problems with pinging and dieseling if you remove EGR. Not having EGR greatly increases the combustion chamber temperature. Not to make you paranoid, but if you're running a stock timing curve without EGR, your valves and piston surfaces are at an increased temperature, it just may not be enough to make the engine ping. I've had mixed results. The EGR valve has gone out on pretty much every Ford I've ever owned. Sometimes it doesn't seem to affect performance, but other times it has pinged really bad on acceleration and I've had to install an adjustable vacuum advance, and in another case rejet the carburetor.

What kind of places did you look at for the leak? Sometimes I find it's hard for a leak to show up with the spray test unless I lean the engine out to the point it barely runs. That way, it's really easy to find a jump in idle. Check the carburetor base, and look for any open vacuum ports, especially if your emissions equipment has been removed.

It is very unlikely that the vacuum advance is causing this. If you want to make sure it works, use a short length of hose to draw vacuum on it and see if it moves the distributor base plate while you have the distributor cap off. If it's moving, the advance is good. If it doesn't move, you'll want to replace it. Replacement advances are usually adjustable, so you may have some added tuning involved if this is the case.

 

Thanks for the info. The engine in my Bronco is completely stock without egr with no pinging but I run 89 octane fuel in it. I don't run regular unleaded in anything I have, not even my tractors. I have a 1944 John Deere A tractor with high compressions pistons and I run 93 in it, lol.

Also just to clarify the metal tubing that goes from manifold to carb is cracked and it is the one that you said has a vacuum signal. That is something that needs to be fixed to have better performance?

For checking the intake gasket, I sprayed carb cleaner around both sides and the ends. I will re-tighten the carb mounting nuts to make sure they are tight since I just installed this carb about a week ago and make sure everything is plugged off that should be since all emissions equipment is removed.

 

If that vacuum line is ruptured, it will cause a vacuum leak. This needs to be corrected for the engine to run properly.