I have a 1985 F-150 with a 302 and a 2150 carb. It currently has an issue where I have to pump the gas an excessive number of times (as many as 20, if it sits for a week) before it'll actually turn over. Even after that, if I press the pedal down it stalls out. I have to press and very rapidly release it another 10 or so times until I can finally press it and hold it without it stalling. The number of times I have to press before starting depends on how long it's been sitting. It has a new accelerator pump, since that was the first thing I thought it could be. Any other thoughts? I'm at a loss on what would be causing this.

 

You said, "I have to pump the gas an excessive number of times...before it'll actually turn over". So the starter isn't even turning the engine over? Or did you mean that it isn't firing?

This is fairly common. When the truck sits for awhile, the carb bowls lose the fuel that normally sit in them. It's not you pumping the gas that is making the difference, it's the fact that the engine is cranking over and the mechanical pump takes some time to pump fuel from the tank to the carb bowls. When the bowls finally get some gas in them, that's when the engine fires.

 

Is it ok if you start and stop during the day? I found my truck did this after it sat for a couple of weeks, and it turned out to be the large port on top of the carb was letting the fuel evaporate out of the fuel bowl. If it happens only in a few days, there could be a check valve in the pump that is bad. Is your truck all original? I am surprised you have a 1985 302 and it has a carb.

 

Yep my 300 dose the same thing as it will sit for a week till next trash day.
You need to crank it and pump that 20 times or so till it lights off..
I would also check that the choke is working as it should as it dose not.

So Dave what is this check valve in pump you talk of?
Would that be in the fuel pump and the gas in the carb is draining back to the tank?
I think not!
Where dose the gas enter the carb?
Yep at the top of the carb and there is no tube to the bottom of the carb bowl to pull the fuel out.
It is evaporating out when sitting.
Dave. -----

 

My 300 I6 did it with the factory 1bbl Carter. My 1995 Mustang with a 302 and Edelbrock 750 did it, and the 351w with Holley 750 DP did it, too. Now my 300 I6 does it with a Edelbrock 500. I've just learned to accept it lol.

 

It's today's gas blend that makes it evaporate fast add a little heat and it goes faster.

Funny thinking about this my 70 AMC Javelin with a Holley 600 carb dose not seem to evaporate the gas as fast.
I only start it to move it out of my garage to work on something else then back in it goes..
It dose not run much so no real heat bud up..
Only thing I habe done to the gas is add stable to it a while back
Dave. ----

 

Only later build '85s had EFI.

EDIT: EFI was offered as an option starting in 1984 for the 1985 model year (Wiki). I based my previous statement on what I was told 35 years ago by my Ford dealer. I waited and bought a 1986 as I did not want to be a first year adopter. IMO, I should have waited for the '87.

 

Mine is a 9/84 build, so I was right at the beginning of the model year.


Sorry, wrong choice of words. It turns over repeatedly but takes a long time to fire. If it takes too long to fire, I have to make sure i drive it for a good 30 minutes or I'll repeat the process and end up with a dead battery in a couple weeks.

During the day it's great, and usually for the next 12 hours or so. I'd definitely believe it was evaporating out of the fuel bowl. Any suggestions on how to solve that? There's a fuel bowl vent with a hose connected to the fuel vapor canister, and that canister doesn't look like it's sealed.

 

I installed a wooden spacer between the manifold of my M-block 400 and the carburetor (EGR has been removed) to mitigate boiling gas in the fuel bowl (yes, it boils in there) and that works pretty well. The M-block has an exhaust crossover in the intake manifold, not a coolant crossover.

Anyhoo, this thing for a 4V:





https://www.summitracing.com/parts/edl-8720

 

I guess it could be boiling, but I think it's likely just evaporating. Gas evaporates rather quickly. Mine will do it after sitting a week or two. Usually, I use some starter fluid sprayed on the filter and that brief startup pumps a decent amount of fuel up. I'm lazy. My cousin has a syringe that he uses to pour into the fuel bowls of a lot of carbs before he cranks them, but that requires taking the air cleaner off, and...again, I am lazy.

 

I pp the pedal like he'll and crank at the same time

As soon as gas is in the bowl and pumping it will fire up.
Dave. ----

 

Yeah, that's what I've been doing. I was hoping someone had a solution to keep it from evaporating so quickly (or at all), but I'm guessing that everyone just pumps the gas until it starts up.

 

My truck (351W 2V) did the same thing if not driven for several days. An electric pump conversion took care of the need to crank and crank the starter to replenish the carb float chamber:


https://www.ford-trucks.com/forums/1...tallation.html

Now if I haven’t driven in a few days, I simply run the pump for about 5 seconds and the engine fires up immediately.

My primary reason for the electric pump was to take care of heat-related problems, but it also took care of refilling the carb after infrequent usage.

 

You didn't show the hose coming out of the carb? It will have a solenoid in the line, and then it does go down to the charcoal canister. I plugged my port off, and the evaporation problem went away, but having it plugged caused a little extra cranking on a hot day.

 

Do you think that is because the fuel vapors are now going into the carb from the bowl vent, yes there is one in the carb opening also, and flooding it?
Dave ----