Help Quick! 400m Quit And I Need This Afternoon!

[rusty ol ranger]

Ok...heres the story.....

78 Ford F350 Dually, 400M, 15K on motor, 4sp.

Went to pick up an old truck cap this morning, run good, got there came out and fired right up, pulled out and about 5 seconds into 3rd gear it started losing power, like it was fireing 7 cylinders, mashed the clutch in, revved it up, it came back to life.

It did this about 3 times on the 10 mile trip home, didnt smoke or backfire or nothing, just didnt have any power. Last time it did it i put it to the floor and it was right infront of my house, it never came back, got it in the driveway, it idled good but when i pushed the throttle back by hand it revved a little and died and that was all she wrote.

I need to know what might be wrong fast......im supposed to pick up a Car hauler and 69 Polara for my cousin this afternoon.....i need it running.

It may have just run out of fuel.....but i dont have any to put in it, but thats not how it usually acts.

Help!

later,
Dustin

 

[rusty ol ranger]

I should add that between the "spells" it ran fine.

 

[85_Ranger4x4]

We have had the Duraspark module in our '80 get hot and act like what you describe a couple times, we put 1/4" of washers under it to let some air get under it and it seems to help. You may have cooked yours.

Breaking/bending pushrods have also been a problem on ours lately, but when that happens it doesn't come and go. It sounds like a lifter tick for awhile before one lets go, 2 have bit the bullet in ours so far this year.

 

[rusty ol ranger]

Youve also got like 400,000 on yours to

I dont think its an internal problem.....my dad said it might be the fuel pump.

later,
Dustin

 

[85_Ranger4x4]

It shows 65k on the clock, it was a farm truck and has been a service truck for 15 years, so the actual milage is unknown. This 400 was put in it out of another truck (farm truck again) about 10 years ago after the old 400 died of what this one is trying to become. We are suspecting oil is not getting to the top end like it should, it really could use a rebuild. The engine has more than earned it, only problem is the bodywise the truck needs rebuilt too. The biggie is do we fix it up or find something newer, it would be nice for the image of the business to have something that looks a little nicer.

 

[rusty ol ranger]

You can get a remanned 400M for 1500 bucks....alot cheaper then a new truck.

later,
Dustin

 

[MAKG]

I doubt it's the fuel pump, but it could be a leaky line or plugged filter. Or just heat (vapor lock -- a risk for mechanical fuel pumps).

If it were running on 7 cylinders, your symptoms wouldn't be nearly as severe. It would shake at idle, but you would still have 7/8ths of normal torque. It's either a mixture problem or a central ignition problem (like the coil or dist cap, or perhaps wild timing).

I'd suggest looking for vacuum leaks. Are all the vacuum lines properly installed?

Is the choke working? Are all the carb rods still connected and moving freely?

 

[rusty ol ranger]

Choke was the first thing i checked.......it is working properly.

All vaccum hoses are fine.

It idled fine....and it never really acted like it run rough....just had no power whatsoever.

thanks guys!

later,
Dustin

 

[85_Ranger4x4]

You can get a remanned 400M for 1500 bucks....alot cheaper then a new truck.

later,
Dustin

Plus a bed, fenders, doors, cab mounts, steering (it doesn't really go perfectly straight), a hood, a grille (darn turkeys) and enough paint to make everything the same color would get a newer truck with fewer problems. By the time we would get done how much of our truck will be left anyway?

 

[AllanD]

Bad fuel pump clogged fuel filter, dying duraspark module.

what they teach boyscouts about fire is "fuel, Air and ignition source"

The same thing applies to engines, Fuel, Air Or Spark.

Lose any of the three and it stops running.

I doubt your problem is air (clogged filter or slipped cam timing)
that makes fuel and spark more likely.

Back to basics.

AD

 

[Will]

Sounds like it's starving for fuel to me. Pull the hose off and crank it into a jar to see if it's gushing properly.