'79 F250 - Backfire - Feeling at the peddle, no sound
 

Hey all,

my truck is backfiring like crazy. Details... battery is great. Tested the alternator. Great. The starter is new. The ignition switch is new. All electronics are working. Brand new starter solenoid. Brand new battery terminals. Passed smog in CA so I know it's not related to fuel or fuel leak/evap.

I'm at a loss. It's not backfiring at the exhaust. It makes no sound at all. My acceleration pedal just loses pressure and clicks. Hell, I didn't even know that was a backfire but had a mechanic in my truck once who called it out. This was a couple of years ago. Then it was a simple spark plug issue. But i've only put a couple thousand miles on it since then so I doubt it's the case.

Anyone have this issue or familiar with it? Would this be the carb backfiring or would that make a sound? And yes... I realize I spelled pedal right in here and wrong on the thread name lol.

Please help!!!

-B

I don't know how much help I might be, but since nobody has attempted to provide some possible help , I figured let's see what we can do.

When you say backfire, so we are on the same page, do you mean it is stumbling and firing back into the intake or somewhere else?

Backfire can have a few causes among which could be just lean fuel mix or maybe spark being in the wrong place at the wrong time.
Could you tell us just what you have done to the engine so far?
The more info you can provide should maybe give us some idea what to go after.

Welcome to the site..
The pedal click, and loss of pressure or feel (?) sounds like the first task would be to look at all the linkage.. Pedal feel should never change with a carburetor system, running good, or bad..
How does it run at idle?? Smooth?
How long ago did it pass emissions?

When only backfiring out of the intake,,, timing is spec? Vacuum/centrifugal advance working/ranging? Some of the old 351M/400 would spin the harmonic balancer ring making timing just a guess.
They also had valve spring breaking issues early on.
EGR sometimes would hang, or could flow unmetered if the control solenoid failed.
Exhaust restriction could cause popping out the intake, generally with a flat throttle when under normal ops.
Good quality fuel??

SThanks for the response. Basically as I start to accelerate the pressure at the pedal (and not always) basically loses all pressure and it makes a clicking sound and then immediately catches itself. There is no other noise than that. No backfire at the exhaust and no sound from the engine. As I mentioned before, I did have a mechanic in my truck once and he called it out as a backfire. Even I thought that was strange but trusted his word. He fixed the spark plugs and it solved the issue. This was a few years back. I only put about two thousand miles on the truck each year. Could it be the timing? Other than this hiccup it runs real well.