LambeauLeap

I have an 84 F150 4x4 with the 302, and auto trans. She runs perfect from 5mph+ with tons of pep on the highway and the idle is smooth. The only problem is that it likes to stall after coming to a complete stop. Like if I'm waiting at a stop light right when I hit the gas it stalls. It starts right back up and will be fine until the next time I stop completely. It also stalls if I have a trailer and I begin to slowly back up.

The problem seems to happen more when its warm outside. It didn't stall at all when it was like 10 degrees out. Last summer when it was 118 degrees in Oklahoma I would shift it into gear and it would stall out like 5 times before it was drivable. Could it be my choke?

I've replaced a lot of vacuum lines as they were almost 30 years old. The transmission has recently been rebuilt so it shifts great. Any ideas would be greatly appreciated!

Roger Mabry

I have replaced everything, checked everything two or three times. It passes CA smog easily and otherwise is "perfect" (except the 11 mpg).

Until my truck is warm - temp gauge needle has to get "to O/R" in NORMAL before it will stop less often.

At times I have a surge at idle that is also unexplained. Have checked for
vacuum leaks, all hoses are new. No codes in the computer....our CA emission stuff is stringent, but all is working with even new cats. Carb has been rebuilt, distributor parts changed inside and a complete tune-up with
compression check done.

Will be interested in following this posting.

LambeauLeap

I think I solved my problem. The breather filter looked like it hadn't been changed in 29 years... I'm not sure if this is the fix but the truck only stalled once this evening on a long test run, whereas before it was at virtually every stop.

LambeauLeap

I spoke too soon, it is cold and rainy today and it stalled out even more than usual. Is my choke supposed to be completely shut when starting cold? It opens up fine when the motor is warm, but it stays open maybe a quarter of an inch even when starting cold. Is this normal?

Roger Mabry

Choke is set by turning on key and pressing accelerator to the floor. Mine only goes totally closed when it is cold enough (the amount of choke is variable).

"The Motorcraft 2150 carburetor has two main bodies, the air horn and the throttle body. The air horn assembly, which serves as a cover for the throttle body, contains the choke plate and vents for the fuel bowl.

An electric choke system is incorporated which opens choke plate within 1 - 1-1/2 minutes when under hood temperatures are above approximately 55°to 60°. The electric choke system is supplied current to open the choke when under hood temperatures are between 54 and 74°F."

Sounds like you may have a sticking or improperly set choke. Read on the web how to set it up or just purchase a rebuild kit. Parts are available for these old carbs and they work well when properly done.

LambeauLeap

Thanks, Roger!

I adjusted the choke and it hasn't stalled since and there is no hesitation on take off. I think that was it!

Half ton

Don't ya just love the old trucks.That senero would have cost you a small fortune on a new truck at $120.00 per shop hour lol. I had similar issue last summer with mine thanks.

ttrimaldi

I am having very similar symptoms as the original poster. I have recently bought the truck (1984 F150 XLT 2WD with 302 and AT, 2150 (I think) 2bbl carb with electric choke and dashpot, still has what looks like the original duraspark ignition with blue plug). The previous owner said that it sat for a while and it looks that way (dusty, leaves under the hood, etc.). When I bought it, it cranked and idled up as it should. After it warmed up, I had to step on the throttle to get it to idle down. At that point, it ran well at high speed, but stalled when I accelerated from dead stops. I figured the carb/fuel filter were dirty, so I replaced the fuel filter and liberally used sea foam to try to loosen up the crud in the carb. The stalling problem did not improve, and starting got worse, so I decided to rebuild the carb. There was sludge & build up in the bottom of the bowl, especially around the power jet which is what i expected. I soaked the venturi assembly and other smaller parts (power valve bowl, venturi screw, check ball weight, idle air screws, bowl jets, etc.) in carb cleaner for a couple hours, and then used a parts cleaning brush and the carb cleaner solvent to clean the rest of the carb body (it wouldn't fit in any metal container I had). I used compressed air to make sure all passages were clean. I set the float according to the chart in the Walker kit to 9/32, reassembled everything, and reinstalled the carb. I did not touch the adjustment to the electric choke. The idle air screws were at 3 1/2 turns out when I took it apart and I reset them to the same when reassembling. I have found on here and other places that 1 1/2 to 2 1/2 are typical starting points. I have tried each of those with little effect.

The truck cranks ok now, but the main issue is that it stalls out within seconds (10 max) when you shift into gear (R or D). RPMs drop way off (based on sound, no tach), and it dies. I can use the throttle to keep it running while in gear and once it's moving, it responds as it should. I suspect a vacuum issue. This has so many vacuum lines, ports, and valves, that it's gonna be a nightmare to trace. I don't want to have to replace all those lines if I can help it.

Other symptoms are that I have to hold the throttle about 1/4 way open to get it to start when hot. It typically idles a little high, accelerates well under no load while parked, and will accelerate well while driving at speed.

Any thoughts/help are appreciated.

Tony