Okay so onto problem #3 that I've found in my process of getting this thing back on the road. 85 F250, 460. It seems to be starving for fuel. Twice now I was able to get it running on its own. After driving somewhere or idling for several minutes I would turn it off then it refuses to start again. I had someone spray starter fluid down its throat while I cranked it, and it fired and ran til they stopped spraying. I disconnected the main fuel line into the carb to make sure it was getting fuel, which it is, though not pumping out as much as I would expect. The little ceramic filter is almost new looking, definitely not clogged. So whats the deal?

I have tried spraying all the jets with carb cleaner to no avail. Is there another fuel filter, other then the little ceramic one inside the main fuel inlet on the carb?

Other ideas? Thanks in advance.

 

Yes, each tank should have a sock-type filter at the end of the pickup tube.

Now tat you"ve identified the quantity as suspect, I think you should now use a real pressure gauge to measure output pressure, and maybe figure out the factory specs for the flow rate and compare that to what you're actually seeing.

Is this electric fuel pump(s) or mechanical?

 

i believe my truck has electric pumps, one per tank. But I only run off the rear tank, the front tank's pump is dead.

Pickup tube? sorry carb engines are new to me I've always owned imports and newer stuff.

 

For illustrative purposes, I'm first showing a tank sending unit that doesn't have an electric pump with it; I'm using this picture because the parts are easier for me to write descriptions of.





OK, the bottome RH corner you should see the brass float attached to a steel rod, this is the thing that floats up & down as the gasoline level changes and causes your gauge to read accordingly.

To the left of that float - just behind where the rod bends upwards - is a filter that's close to the same color as the brass float, it's on the end of the pickup tube - this is from where the gas gets taken in.














The sending units with the pumps aren't as clear:



In the above picture, the filter is the white thing attached to the end of the brass-colored pump. The float is a dark, flat object to the left of it.



My original point being, those in-tank filters disintegrate & collapse after a while.

 

Ah, I was really hoping to avoid dropping the tank(s). Especially since both have quite a bit of gas in them. Any tips on this, if it turns out that what I have to do?

 

Siphon as much gas out as you can, to relieve the weight. Then use a transmission jack to help with the removal. The large plate on a transmission jack is easier to balance on, vs. a regular jack. And take your time, to disconnect, and label your hoses and wires, just in case.

 

Okay so its not the in-tank filter...I confirmed that there IS fuel coming through the line that goes into the carb, its just not getting through the carb to the jets. I have disassembled the carb and sprayed the hell out of all the ports with carb cleaner, no good. Earlier today I rebuilt the sucker, replaced all gaskets and such. WTF is the problem? This truck is really starting to irritate me. Why would gas be getting to the carb but not through the jets to the engine? Thinking of just buying a new one but I didn't really want to spend that much money right now, being jobless.

 

Is your diagnosis of fuel not proceeding through the carb to the jets into the engine based on the following:

IOW is the diagnosis based on the fact that it's hard to start a warm engine?

If so, I question the diagnosis, this is based on listening to and watching the fuel in my carb boil out of the bowl after shutting off a fully warmed-up engine.

I installed a wooden carb spacer when I rebuilt my engine (a 1981 400) to keep that from happening again.

 

I need to know how much fuel pressure you have at the carb before going anywhere else. If there is a problem inside your carb and you do have 5-7 psi at the FP then you probably need needle n seats in the carb which would be replaced during the carb rebuild, then your accelerator pump needs adjusted, then set floats and ide mixture screws.

 

Well now it wont run on its own at all, warm or cold. I couldn't test for fuel pressure since AutoZone my truck is stuck at didn't have a tester with the right fitting, but I had my buddy crank it while I watched the line (disconnected from the carb) and there is fuel coming out of it. The last time I took the carb off to again disassemble it and try spraying all the ports with carb cleaner, when I tipped it gas poured out. So gas is getting into the carburetor just not through it.