1985 f250 460 stock carb stalls out

[Johnbi]

New to this I got a 85 f250 with a 460 and would like to share some issues and hopefully get a response with someone who has had the same problems with a solution 👍 I just got the truck and it runs well if you stay in the two barrel or don’t have it under load like hills when I get on it or even drive normal but hit a hill it stalls out like it’s out of gas but if I let off and let it idle it will run fine again .. I just replaced the carb with a rebuilt oem hoping it was the accelerator pump or power valve but it acts exactly the same I’m thinking it’s low fuel pressure it has fuel pumps in the tank but only the front tank works do those fuel pumps loose pressure or just go out when they are done .... thanks in advance

[Gary Lewis]

I'm assuming by OEM you mean you have the Holley 4180C, as shown here: Documentation/Fuel Systems/Carburetors, Chokes, & EFI/Holley 4180C.  Right?

When the truck "stalls out" does it do so like turning the key off?  Or does it kind of bog down and if you back off the throttle a bit it starts coming back slowly?  Or, does it pop, backfire, and miss?  

Chris/ctubutis is fighting something very similar and I think his may be rust in the fuel tank plugging filters.  But he has a mechanical pump on the engine, where you have pumps in the tanks.  I would have thought that those pumps either worked or didn't, but perhaps yours is marginal and you just have enough gas to putter around and not to climb hills.

Anyway, tell us more about the symptoms when the problem occurs.

[ArdWrknTrk]

Welcome to the Forum!  

Bill (85Lebaront2) is our resident carburetor master, and if you can describe the symptoms exactly I'm sure he has better answers than me.

Do you still have the stock vapor separator, 'T' can in the fuel line near the carb?
If you're not straining up a hill, and just punch it how does it respond?

I ask because it seems you just have a volume problem, not a pump problem.

[Johnbi]

Yes still has the stock T

[Johnbi]

Yes stock 4180c it will bog out like it’s out of gas then I let off and it will idle fine and drive fine as long as I’m light on the pedal today I drove it light on the pedal but lower rpms in 4th gear going up a light hill and it acted up on me like it was out of gas I push in the clutch and let it idle and it takes off fine almost like the float bowls filled back with gas

[Gary Lewis]

Try a lower gear when it does that.  A gas problem usually is worse in a lower gear as it takes more gas then.  But an ignition problem is better in a lower gear as it lowers the cylinder pressure.

[ArdWrknTrk]

Consider removing it and soaking it in lacquer thinner for an hour or more, then either back flushing or blowing it out from the return port.

The screen inside catches rust and gets gummed up too.
This will lead to fuel starvation at high revs and under load.

One thing people who are not familiar with carburetors don't grasp right away is that you are working from a reserve (float bowl) whereas with injectors, if the fuel runs low it just stops working.
You describe fuel starvation, but there is NO pressure after the float valve.

[Johnbi]

I cleaned that T out it was full of garbage put it back together went about 2 miles it was running awesome then started doing it again I’m assuming there is rust in the tank and it’s plugged up again I’m going to take it apart again see what comes out of it but seems like I’m going to have to clean the fuel tank out to get it to quit

[ArdWrknTrk]

Glad you found the problem.  

You might try an inline filter down on the frame rail, away from the heat of the exhaust manifold.

A new tank is $100 give or take.
It's hardly worth the acid and paint thinner, let alone your time to try and clean it out.

[Gary Lewis]

ArdWrknTrk wrote

Glad you found the problem.  

You might try an inline filter down on the frame rail, away from the heat of the exhaust manifold.

A new tank is $100 give or take.
It's hardly worth the acid and paint thinner, let alone your time to try and clean it out.

/\ /\ /\  What he said!  

I've tried cleaning a tank out and it did NOT work.  Buy a new one.

[Johnbi]

I replaced the two small sections of rubber hose by the frame and put an in line filter now she is running good it had original plug wires that I changed it’s like a new truck now

[Gary Lewis]

Congrat's!!  But keep a close eye on the fuel filter.  If you have rust in the tank then the filter may plug.  But it'll be a lot easier to replace it than to clean the hot fuel handling system or the carb.