1984 2wd starting problem and gas mileage problem

[ponylee]

Hi all. Excellent forum here, especially for a newbie as myself. I bought a 1984 F150 that supposedly didn't need much work (from that lil ol man who only used it for church on Sundays). Anyways, the truck has cost me a bundle so far and I still have several problems.

When I start the truck, I generally pump the gas petal twice and turn the ignition. It starts right up, revs high and then stalls a few seconds later. I did a full tune up on it (plugs, wires, cap, rotor, gas filter, PCV valve, air filter, mixture, timing) and it still does this. Any ideas what I should look at next?

Also, I am getting terrible gas mileage. After the tune up, my mileage seemed to go from about 6 mpg to 12 or so. What kind of mileage should I be getting from an 84 and what can I do to improve it? It has the 351 engine with a 2 barrel carb.

Thanks in advance for any suggestions.
Lee

[mustangmike351c]

is the choke working proper? sounds like its stuck open. 12mpg is as good as it gets maybe a little better on the high way

[unclebubbles]

There were several carbs available in that era truck. If you have the variable venturi carb on it, they were (are) notorious for poor performance, fuel economy, and are hard to tune and keep working properly. If you have that carb, i would suggest going to a regular autolite 2bbl, from an earlier truck. You can still find em in junk yards, or rebuilt, and they are considerably cheaper than the 7200 vv. You can adapt it with only a few minor modifications. That engine is capable of outstanding performance, and fuel mileage in the 18-20 mpg range, but not in stock trim. Ive owned several trucks with that engine, and modified some for other people , that would consistently get 16-18. Dual exhaust will help considerably, and headers will add even more. You can get a good set for under 100$. Changing to a small 4bbl carb and intake will help, providing you can keep your foot out of the secondaries. The stock ignition leaves alot to be desired too. I like to use the MSD ignition modules, pulse triggered with the stock distributor. You can switch to an earlier model distributor with vacumn advance, and it works well with the MSD units. I believe the 84 had the crank triggered system, with a spark control module. Just a few things in a long list that you can do. If you dont want to get too heavy into the mods, at least get rid of the vv carb, if thats what you have, and installing dual exhaust will help some. Otherwise. like mustangmike said, about 12 maybe 14 is it.

Edit: Sorry, forgot your first question. The starting and going dead problem sounds like a vacumn leak, or maybe a stuck egr valve. Check all hoses and vacumn sources for leaks.