77 400 has me stumped

[rusty ol ranger]

77 F250 400.

Truck sat in my driveway not moved or started for two years.

Some gas and a good junkyard battery it fired right up. Started the 7 mi trek to the old house and about 2 mi in it quit. Keep wacking the carb and it would run good a little further then putter and die.

Ok so fast foward to a few weeks ago....i finally got around to getting the carb off and rebuilding it. Stripped it down, replaced everything that entails a rebuild, cleaned itl blew it out, etc etc.

Put it on the truck, primed it, hit the key it fired up and ran for about 15 seconds then died. Would not start again.

Waited about 30 seconds, hit the key fired up ran 15-20 seconds and died....did this over and over. Pulled the cover off the carb and seen there was barely any fuel in the bowl.

I had a new fuel pump so for poos and giggles i changed that.

Same thing.

Now when i rebuilt it i set the mix screws to initial and also set the float to proper level. But i pulled the cover off and set the float up higher....damn near as high as itll go.

Now it will idle good and strong but if you sit there and hold the accelerator at about 2000rpm itll run maybe 45 seconds and quit....just like you hit the key to kill it. But then will immediatly fire back up.

I cant set the float any higher, and i can suck the fuel line by mouth and pretty easy get a mouthful. So i dont think theres any obstruction. Filter is also new.

Ive never had a duraspark module fail....could it fail like this? When it is running it sounds good and strong.

My gut says its fuel related but when it dies it just dies....not like it did before where it would putter and stumble first like it was running out of fuel.

Kinda at a loss here....any ideas?

 

[Blmpkn]

"Damn this old truck of mine!" Says the guy who hates New stuff equipped with obd ports

 

[rusty ol ranger]

"Damn this old truck of mine!" Says the guy who hates New stuff equipped with obd ports

Atleast im confident in my ability to get this one running lol. Ive also had it since 2012 and its the first time ive really had an issue. I think its owed a problem or two lol

 

[PetroleumJunkie412]

Rusty, we've been over this.

There is a wizard that lives in the carburetor.

You've upset him.

 

[rusty ol ranger]

Rusty, we've been over this.

There is a wizard that lives in the carburetor.

You've upset him.

Hes stumped to.

 

[ericbphoto]

I'm not pro at this. But I would think that if it fires for 10-15 seconds, you have spark. Probably not an ignition problem.

That's just a gut feeling.

 

[rusty ol ranger]

I'm not pro at this. But I would think that if it fires for 10-15 seconds, you have spark. Probably not an ignition problem.

That's just a gut feeling.

Right. But thats why i was wondering if it might be the duraspark module. If its "giving up" but not tottally gone yet.

 

[fastpakr]

I guess that's possible but if the behavior changed immediately after carb work it's not where I'd focus.

 

[19Walt93]

If there's very little fuel in the carb after it quits the ignition module isn't at fault. I assume you replaced the fuel filter and it might be worth looking at the one in the tank. I've also seen rubber fuel line collapse under suction and restrict flow.

 

[fastpakr]

You could temporarily bypass the fuel system too by supplying fuel directly to the carb's fuel line. Make sure the carb works, then chase the fuel issue if it's external to the carb. Then if there's still another (separate) issue, solve that independently knowing the carb and fuel system are solid.

 

[rusty ol ranger]

You could temporarily bypass the fuel system too by supplying fuel directly to the carb's fuel line. Make sure the carb works, then chase the fuel issue if it's external to the carb. Then if there's still another (separate) issue, solve that independently knowing the carb and fuel system are solid.

I actually was thinking of that.

If there's very little fuel in the carb after it quits the ignition module isn't at fault. I assume you replaced the fuel filter and it might be worth looking at the one in the tank. I've also seen rubber fuel line collapse under suction and restrict flow.

Right...after i adjusted the float up though the bowl is full. I forgot to add that in the original post. Filter at carb is new,...i suppose it could be the pickup sock but like i said i can draw fuel up pretty easy by mouth to the carb.

I guess that's possible but if the behavior changed immediately after carb work it's not where I'd focus.

thats why my gut says its fuel. Just not sure why its still doing it with the float damn near maxed.

 

[fastpakr]

Thats why my gut says its fuel. Just not sure why its still doing it with the float damn near maxed.

How does it do with a shot of ether?

 

[rusty ol ranger]

Only other possibilty i just thought of was i had to change the metal line from pump to carb, i couldnt bend it properly to run it up back by the water pump like it was factory so i just did this....

But its not kinked or restricted in any way.

 

[rusty ol ranger]

How does it do with a shot of ether?

i did that intially before i redid the float and it was kind of a 50/50 shot. Sometimes it would sometimes it wouldnt start. I wrote it up to maybe not spraying enough in.

 

[snoranger]

I’ve had a few duraspark modules go bad before (before meaning 20+ years ago when there were still carbureted cars on the road), they usually shut the engine down like you turned the key off and won’t let it restart right away. But I’d throw an inline spark tester on the coil wire... just in case.