Why won't my car start without priming it?

Question

I have a big block 460 cubic inch 1970 Ford. The car will NOT start unless I prime it by pouring a small amount of gas into the carb. Then it will run just fine and run forever. Until it is shut off. Then must be primed again. What is the problem?

Answer 1

Fuel pump is loosing prime. Needs to be replace. had the same problem with an older Chevy pickup.

Answer 2

It has been a long time since I have mucked with carburetors, and most of those were with GM cars, but, FWIW, as I recall, a 'sticky' valve caused most of my problems. Here are a few suggestions (obviously, without seeing your vehicle, I can't make a specific diagnosis!):

1) When the car is COLD, remove the air intake to expose the carb, GENTLY push open the valves, and spray the edges where the choke valves meet the carb housing with a carburetor cleaner, wait a few seconds for the stuff to do its work (i.e., dissolving gunk), then wipe the area with a clean cloth (do NOT use paper towels). Start the car (you don't have to replace the air intake, but do NOT rev the engine!). If that doesn't seem to work, turn the vehicle off, then peek into the carb where the choke valve is using a flashlight. If it looks "gunky", then spray the interior with the carb cleaner, then start the car (NOW you can rev the engine, but do so gently; if it doesn't work at slow revs, it ain't gonna work at high revs, and there's no point in wasting gas! You may notice clouds of smoke coming out of the exhaust; that's just the dissolved gunk; don't worry about it; it'll go away within minutes of normal driving). Note that if the interior of the carb is badly gunked up, then you may need to remove the carb and clean it thoroughly. You don't have to take the carb apart, but do write down or otherwise indicate where the vacuum hoses and other attachments go, or you'll have a devil of a time putting them back correctly! A mechanic's "trick" (albeit a potentially dangerous one!) is to put the whole carb into a vat of gasoline or similar gunk solvent, and just leave it overnight, then remove it from the vat (the dirty gas may be filtered and re-used in low-performance engines, such as a lawn mower; please dispose of the remaining gas in an environmentally safe way!), then allow the carb to dry thoroughly (give it a couple of hours; if you wish, you can cloth towel dry all the parts, but it isn't easy to get inside the carb, unless you take it apart, which is a big job!). Re-attach the carb and attachments and hoses, and see what happens.

2) There is a tiny cotter pin or clip where the accelerator and/or choke and/or pump rod meets the carb. There may be more than one (some are internal to the carb). Sometimes, the fragile pin snaps off, leaving the accelerator or choke or pump rod appearing to be "attached", but, otherwise, incapable of moving the valves. If you can't find the exact part, any U-shaped metal wire will do the trick (I used to take a paper clip, break off most of it, then bend the rest to a U-shape, then twist it so it would stay attached to the accelerator or choke or pump rod (having said all this, if this were the problem, you probably wouldn't be able to drive the car faster than idle speed!).

3) Your vacuum line(s) may be cracked. GENTLY pull off each one (ONE AT A TIME!!!) on both ends going to and from the carb, and check for cracks, holes, tears, etc. If there's enough rubber, clip off as much of the bad end(s) as possible (clean the connection, as well, if necessary, using a cloth), and re-attach. Sometimes, the rubber has "fused" to the connection, and it may require a razor to cut off, but be gentle, as you may be cutting into a plastic housing!

4) Faulty pump return spring. This is a much more involved fix, which I won't go into, here.

5) Spray any moving EXternal parts and springs with oil (a two-second shot should be more than adequate; dry any overspray).

Good luck!

Answer 3

I hope you're not driving that beast every day !!
If pumping the accelerator pedal doesnt work then the acceleraor pump is probably bad. Try squirting starting fluid into the air intake nozzle instead of pouring raw gas down the carb throat. Less time, safer.

Answer 4

It is not the choke or Accelerator pump. If it were the accelerator pump it would bog when you hit the gas. It most likely is the fuel pump going bad. I would replace the fuel pump. The diaphram is getting weak and probably not strong enough to develop enough pull to prime.

Answer 5

accelerator pump is shot and the choke is not working

Answer 6

maybe your carb is leaking also check your filter it may be dirty in your fuel line.