68 f100 390 FRUSTRATING COLD START

[mkonecek]

Finally reaching out for assistance.
Have had this truck 25 years. Now the kid is driving it. Sat for 10 yrs solid.
Replaced the intake. Edelbrock. The rear seal is leaking when running, will have to reseal it. (vac leak?)

Had very sour fuel. drained and replaced the pump. Still some crap on the bottom of the tank and no sock remaining but running 2 filters.

Pump failed after 2 months (autozone pump)

replaced it last week with same component. The next morning it would not start. Decided it was the choke. Carter AFB. Rebuild the carb but forgot to adjust the mixture and choke. did that and it has been running well for the last few days. electric choke, just have to wait a few minutes and it drives great.

This morning, would not start. would catch for a half second and die. its only about 60 deg here. Checked the choke and its too far open. Tried to adjust it then heard a spring pop kinda noise. like the coiled spring came undone. choke now just moves freely. no more catching, just a crank, no start.

feels like another fuel pump.

This is simple stuff which makes it even more frustrating.

I could use some thoughts right about now please.

[Jacksdad]

Could well be the pump - I've had a couple fail in quick succession - but you have choke issues too.

Do you have a helper that could check the choke actuation while you're cranking it? Maybe have them manually choke it, either by holding the linkage or by partially covering the carb intake with their hand (always fun when they think it's going to get sucked in, or it backfires ).

[mkonecek]

Im suspecting the pump. I have an older carter street/strip but the diaphragm is blown out.....wish they still offered rebuild kits.

Will be in the 80's today so I hope it starts when I get home. will rule out the pump. I will have a helper later to try both. The kid drives it and we were troubleshooting over the phone. He may have just flooded it while diagnosing for all I know.

Thoughts on going back to a manual choke??

I guess my post is more about this system being so damn simple yet I keep having problems. Don't know if I am missing that one thing that is right in front of me.

[Jacksdad]

I have a manual choke on a factory 2bbl. Works fine.

[basketcase0302]

That spring you heard was the bimetallic spring inside the choke housing, (either broke or came loose) so yes that will make a 390 hard to start even at 60 degrees, (I'd always found my original 360 was the coldest natured engine I ever owned-which I found a blessing a few times in Florida when running low on coolant LOL)!
Even though it's electric it has a bi-metal spring which when warmed up by the engine heat it opens the choke. It should have a small 3/16" steel tube running down to the exhaust manifold heat riser. That's where it gets it's warm air to open once the engine is warm. It's something small-you'll find it, and do you see a stream of gas with the engine off looking into the carb throat when you open the gas / throttle linkage?
Here's what your bi-metal spring on the back side should resemble:

[Ohiotinkerer]

I have a manual choke on a factory 2bbl. Works fine.

Same here........nothing like keeping it simple........

You actually need a choke in Sunny SoCal???????

Back to the subject - maybe its just me but I have always had problems with electric chokes and have just found it much easier (and simpler) to convert it over to a manual setup - 1 screw to set and I can adjust the pull for how warm or cold it is by hand......

[Mancar1]

I used to prefer manual choke, but I put a Holly 600 CFM, auto choke on the 68's 390 a few years back. Have had no problems. Cold start push it to the floor let up and she fires right up.
I have always found that once a choke is set right and working ok, either manual or auto. do not mess with it.
Course in your case it broke on u so you have to. If mine ever starts acting up, yes I will just hook the manual back up.
Just ranting, on some predizone cant sleep.
Keep on Trucking.......John

[Jacksdad]

...You actually need a choke in Sunny SoCal???????

I know, right? And once she's warm, I get heat soak so bad that the starter will barely turn unless I let it cool for a while. Can't win.

[tsherry]

I fought my Carter AFB for ten solid years. WOULD NOT start without starting fluid, no matter what the settings on the carb, float, etc. were. Clean tank, new pump, filters, the whole shebang.

Put on an Edelbrock 4bbl this past summer, didn't adjust it one whit, starts every.single.time without any trouble whatsoever.

[cep62]

Are you sure the accelerator pump is working in the carb?
With out the engine running look down the carb and pump the gas .
There should be two strong streams of gas with each pump , if the fuel pump fills the bowl.

A choke is nice but I've been through several Michigan winters without one.
Just pump the piss out of it , til it starts , then you have to baby sit it for awhile .
A heat stove from the exhaust manifold to the air filter really helps too.

And ,if you have the right size snow brush you can wedge it between the seat and gas pedal for a faster idle.

By the way I do have a Holley with a hand choke on my current plow truck.

It seems the cheesy after market choke cables aren't as stiff as an old factory one so they don't push open as well.

I also think an electronic ignition helps a lot too.

[colnago]

Are you sure the accelerator pump is working in the carb?
With out the engine running look down the carb and pump the gas .
There should be two strong streams of gas with each pump , if the fuel pump fills the bowl..

This was exactly my problem recently. Hard starting, no matter what. Full choke, no choke, etc. Took the carb apart, and found the accelerator pump was torn and missing parts of the rubber seal. Replaced it, and life is good.

Joseph

[mkonecek]

So it has been starting fine lately. Since my post. Now I’m back to fuel starvation. While driving and warmed up already, it will starve. Have to pull over and restart it. Have replaced 4 or 5 pumps at this point. Tonight is the 5 th. Will look at it Sunday. After sitting, I can get it to start but it’s not running fully.
I’m guessing the pump is not pumping fuel. Has a canister filter, an in-line before the pump filter, and I flushed the tank with kerosene before installing this last pump.
Thoughts on an electric pump salving the issue? And is there a way to install an electric pump and wiring it to the ignition instead of a toggle?

[basketcase0302]

Have you ruled out the choke not working right and have you looked down the throat of the carb to verify if it has a good stream of fuel when "flooring" the accelerator pedal? The engine dying when warm then restarting when it cold is typical of an ignition coil-have you verified spark when it doesn't start?

You could easily wire in an electric pump, (but have the same problems IF IT'S NOT FUEL STARVATION). Using a headlight relay and then energize it by using a separate wire from the ignition 12 volt side, (not the ignition wire itself or you'll add to the trucks problems) which you can pick up at the ignition switch. You would need to fuse both circuits, (the 12 volt relay wire that energizes the circuit / and the 12 volts supplying the pump itself) which could be done with inline fuses quickly and easily.

I personally wouldn't go that route-rather than find what is stalling the truck. Keeping in mind our cheap gas is made to last no longer than 30 days, (is the fuel in the tank fresh)-and 90% of the bump owners here have fuel tank issues. There is usually so...much crap in the bottom of the original tanks that simply "flushing" does little to nothing to solve an issue with debris in the fuel circuit. There is only 1/8" to 1/4" between the bottom of the 3/8" fuel line that picks up fuel and the bottom of the tank making a clog there happen very easily. Transfer the fuel out of the tank / inspect with a cheap probe from harbor freight / be prepared to replace the tank as most of the original ones are way...past their life's end.
https://www.harborfreight.com/digital-i ... 61839.html

[tsherry]

Seems like I post this a lot, but:

Have you replaced all of the rubber lines in the system from the tank to the pump? After sitting, gas can eat away the bond between the inner and outer parts of the nylon-braid reinforced rubber fuel lines. Under demand, the fuel pump can suck the inner part of a hose closed, starving the truck of fuel. Have had it happen a number of times over the years, including this week with my son's '65 Falcon Van--and I'd replaced all of those lines 20 years ago...

[bigjoep]

Could it be the gas tank is not venting properly? I had a non-vented cap on a non-vented tank and it had trouble starting and running.