runs good for 1 minute then gets choppy, smells rich. and dies.

[nc89]

Have a 85 ranger with a 2.8, 5 speed 4 wheel drive. Truck only has 60,xxx miles I just bought it and the previous owner said it needed a carb rebuild. No problem. I do the rebuild and the same problem exists. Problem is...truck will start pretty well, then after 30 seconds or so the idle will lower, and lower, and no lower, and then it will get very choppy, smell horribly rich and then die. To restart i have to hold the pedal to the floor and did crank for 10 seconds or better, it will fire and I have to keep my foot on the floor until it chugs and chugs to a high rpm when the engine clears up and runs smoothly. Truck will return to idle. It will idle great for 30 seconds or so and repay the above symptoms. I'm at a loss and have no idea what to do. Any help would be AMAZING!!

 

[RonD]

If it smells rich and then dies I would say the carb is dumping fuel into the intake.
The long restart would confirm that because extra fuel needs to be cleared by opening throttle plate all the way.

First thing would be a stuck or misadjusted float valve, when float bowl fills up extra fuel flows into the carb throats and into intake flooding the engine.
Could also be a bad gasket or seal allowing fuel from the bowl to flow out into the throat.

I would disconnect fuel line from carb, block the line, or if electric pump pull the fuse(fusible link), start engine and see if it idles OK until float bowl is empty, so no rich smell before it dies

What carb are you using?

 

[Starlord]

It will have a mechanical fuel pump in 85 if following the above steps. Did you do anything with the choke when you rebuilt it? I'm not sure the choke would cause such a dramatic effect as your describing, especially as early as 30 seconds, but worth a shot. Try just holding it open when you start losing your idle.

 

[kimcrwbr1]

It could very well be the choke not opening. When you hold down on the throttle it is also opening the choke. Pull the top off of the air filter and push the throttle half way down the choke should fully close and as soon as it starts the vacuum pod should pull the choke open about 3/16 inch if not stick a screwdriver to hold it slightly ope and see if it stays running? If so keep in running and see if the choke opens by itself? Next to the start solenoid is the choke relay (funny little animal) what it does is give a pulsing voltage to the choke thermostat on the side of the carb. Pull the wire and see if your getting a pulsing voltage to the thermostat? If not the relay is bad or the connector is dirty.
http://www.ebay.com/itm/Motorcraft-2-barrel-2150-rebuilt-carburetor-with-electric-choke-ford-AMC-/161624138037?pt=Motors_Car_Truck_Parts_Accessories&hash=item25a18ca135&vxp=mtr
This shows the vacuum pod on the back of the pod is the adjuster screw if you have one it may not be opening far enough.

 

[kimcrwbr1]

http://www.ebay.com/itm/D78E-AA-42-6-42-7-ESSEX-1975-1978-MOTORCRAFT-2150-FORD-CHOKE-PULL-OFF-/251790686948?hash=item3a9fe4fae4&vxp=mtr
If it has vacuum pressure but dont open the choke it needs replaced I believe this is the right part you want to double check.

 

[AndyB.]

I don't know of your choke pull off is bad or out of adjustment, I test them with a vacuum pump. The original replacement was E2TZ-9S514-B (Motorcraft CK-2108), which was superseded by E3TZ-9S514-A (Motorcraft CK-2168). These are pretty inexpensive parts and adjustment after installation is pretty straightforward.

 

[AndyB.]

Also, if it's runninh that rich, pull the vacuum line from the EGR spacer to the power valve and check for the smell of gas.