I don't know anything about aftermarket EFI conversions, but I'm pretty familiar with the stock 4180 carb / duraspark system. If you can describe what it's doing (or not doing) maybe I can identify a common issue with a simple solution.

Not saying it's not a carburetor problem, but it's surprising how many carburetor problems turn out to be something else.

The 1980 - 1986 "Bullnose" section also has a good group of enthusiasts for your vintage and you should consider starting a thread there.

 

Might as well give it a shot! I've not got much to lose

Symptom

The engine will start and run approximately 10-20 minutes, more if only idling. During this time, the van drives fairly normally. Attempts to use close to full throttle will shorten the run time drastically. The engine is unable to restart alone, or if it does, will die almost immediately. Accelerator pumping does not improve the situation. It will typically take several hours of sitting prior to a successful start again. It will start on-demand with an ether chage.

Known

Front tank fuel pump is new; rear tank fuel pump is known working; switchover value is known working; inline fuel filter (the metal sponge thing) is new. The 3-port "Hot fuel handling" vapor bypass value was replaced (did not resolve issue) and is currently bypassed completely. When the engine dies, it can be cranked with the fuel line disconnected and the pumps will push what looks like the correct volume.

Unknown

My mechanic took apart and cleaned the carburetor, but I do not know to what degree and I know he did not order a rebuild kit.
No other components have been changed or replaced.

Prior Events

The van made it from New Hampshire to Massachusetts with no problems; thereafter, it ran around town on local trips totalling ~200 miles with no problems. Problem reared its head after I replaced the front fuel pump and replumbed rubber lines and progressed very quickly, starting with stumbling at higher loads but not stalling, and becoming outright stalling a few days later. In fact, it died halfway to the mechanic and I got a buddy with an equally large truck to flat tow me the rest of the way.

My assessment

This makes me think I introduced some matter of debris into the system when I disturbed it. However that meant making it past the pump-side inline filter as well as the metal sponge??

The "runs good for a while" symptoms made me think ignition circuit (like a bad coil that fails when the engine is warmed up). However, the load depency kind of conflicts with this in my mind. On a test drive when we thought we had it beat, it idled at my mechanics' for a half hour, but when I took it out on a main street and tried to do a high-throttle pull, it lasted maybe a quarter mile.

He recommended a complete rebuild by a shop that specializes in carburetors; I was unwilling to do this because of the anticipated cost (and because it will STILL be a carburetor when done i.e. I'd rather spend some more upfront and go EFI if it becomes necessary)

 

sorry, but
I like the late 80s 7L diesel (non-computer controlled) w/ZF or EOD
(but that's another thing entirely). 460 is best used as a race motor

4 this one - carb rebuild is not as difficult as U may believe
(ck throttle shaft bushin inside the carb, new float, acc pump, etc)
Folks here can walk U thru it, here 2 help...

 

As an expert internet troubleshooter, this screams fuel supply problem.
Maybe fuel pressure pushes trash and clogs filter(s) and as pressure drops the trash drops away?
Maybe a venting problem?

 

Your should post your symptoms in the Bullnose section to see what the brain trust over there thinks.

Fuel delivery:

You should have about 8 psi fuel pressure at the Holly carb. More than that and it will flood out. Less than that and you might "run out of gas" under a load.

Low fuel pressure could also lead to vapor lock.

Stock it probably came with a "hot fuel handling" package (to prevent vapor lock) which consists of a little vapor separator canister by the distributor that has a little oraface that controls how much fuel is recirculated back to the fuel tank via the return line.

The little canister is often mistaken for a fuel filter and messing with it can cause problems. Too much fuel being recirculated to the tank = fuel starvation at the carb.

Power supply to fuel pump. The stock fuel pump power supply main circuit does NOT deliver 12 volts to the fuel pump. There is a resistor wire in the circuit that steps the power down. If the pump you installed requires 12 volts and you wired it into the stock system, it's not getting 12 volts.

Ignition:

If you have a weak spark it may idle fine but your ignition will break up under load. I wouldn't swear to it but ether might burn more easily than gas and will fire on a weak spark where gas won't?

Since it seems to run okay cold but fails when hot it makes me wonder about the ignition. The Duraspark ignition modules will sometimes fail when hot, and then work again once cool. Same goes for the magmatic pickup inside the distributor. Typically though these problems manifest as no spark until things cool back down. A bad ignition module will often give a miss fire / back fire and then quit, which does not sound like your problem...

A bad coil can also work okay cold but act up when hot.

I had a "coil problem" that seemed to clear up when I replaced the horseshoe coil connector. After 30 years the original plastic was cracked, the contacts very dark, and the factory wire crimps where they connect to the contacts rather suspect. First clue (besides ignition problems; missing, lost power, bouncing tach) was inconsistent ohm readings while trouble shooting. Cheap and easy to replace.

Beyond that, the key thing to determine is whether the carb is full of gas or empty when it quits and won't restart. If it's full I'd look at the ignition. If it's empty I'd look at fuel delivery.

But the fact that it idles and runs okay when it does run suggests the carb isn't the problem. A bad carb typically will dump too much gas into the motor and you'll run rich or flood out. Or maybe the choke doesn't work right, or the secondaries aren't coming in like they should. But seldom will a carb full of gas starve the motor until it quits.

 

I'd lean towards electrical but w/o actually seeing the vehicle it's a crap shoot.

 

@jbwheels Yeah, my other crusty 80s van (which is EFI port injected) had a similar-feeling problem which ended up being a clogged fuel pump intake strainer. This is why I suspect fuel delivery issues to begin with, especially since I changed the pumps myself.

@BrnFree Good points, I should test the pressure with a gauge. Mechanic said it was yielding the correct volume per the manual but he did not test pressure (to my knowledge) so I was running on this assumption.

Ignition coil and module are cheap enough at Autozone and easy enough to reach that I might just do it anyway later this weekend. The new pumps are all Delphi units listed for the 86 E350 1-ton with dual tanks on RockAuto, so I hope they're correct. Though I feel like 'incorrect fuel volume' is hard pressed to be the difference between running well and completely not at all...

I have some motorcycle hacker friends who insist on having a look at the carb this weekend so I will relay the recommendations in this thread. They did talk about checking the sight plug when it starts failing.

I really want to believe all of this was caused by something I did

 

This thing has had an adventurous 2 weeks!

So to update the poor running - I ultimately traced it back to the fuel tanks being rusty inside.

First though, the selector valve was indeed malfunctioning, so it was a compound problem. You know up there where I said I knew it was working? That ended up being BS. It seems like the contacts that move inside are old or worn, so some times it did not move properly and hence would end up in the wrong position (But I hear it toggle, so "it works!)

So at least I have a new selector valve:




That didn't fix the problem though. Next up, what had happened was when I replaced the fuel pump and replumbed the selector valve assembly, I didn't put inline filters on the lines... Not having a lift or crane (& having to work all on the ground) meant I never got a good look inside the front tank, and the rear tank's condition is also unknown to me. Also, ******* brain fart mistake.

My assessment is that the collision dislodged lot of debris at once into the tanks. The fine rust slurry clogged up the carburetor real good and gave running trouble whenever it crowded the passageways, but otherwise when it settled down, let the truck run. This caused the 10-20 minute delay with the very fast fall-off that made me think ignition.

Well at least I have a new coil and ICM...




It also meant the fuel pumps were giving correct volume and pressure otherwise when my mechanic ran those tests. Then, he rebuilt the carburetor, and based on my informing him that I had serviced the front tank, he did his testing ONLY on the front tank. So the truck ran beautifully for a few days, then shat itself again as it tried to run on rust slurry!

Basically I discovered this condition when I did a fuel volume test on my own and noticed the fuel was heavily discolored and had a huge amount of sediment. I then ran to buy the biggest inline clear filters I could find at Autozone. Here is the hot garbage that ended up in the front tank's filter after only ~20 minutes of running!




And then I ran around to pull the carburetor inlet filter (the little metal sponge). You can SEE the crud in it. And also the fuel hardline I sheared off trying to unscrew the wrong thing:




So then the truck ran great. And has been running great. I went and did about ~50mi of highway driving, making sure to do repeated offramp-onramp full throttle pulls. The carb is obviously not tuned since my mechanic never got a chance to properly road test it - currently seems to run a little rich and likes to backfire a little. I'll probably have him do a final tune....

...but after I replace the bed. A few friends and I pulled the old bed off last weekend. The replacement F350 long bed should be going on this weekend. I'm making a few adapter brackets to turn the van frame locally into the truck frame so the bed bolts on:



So that's where I am now. Whoever surmised it was a fuel supply problem was mostly correct

While the bed is off, I'll likely replace both tanks outright with new ones.

 

Excellent work.
This van speaks to me for some strange reason and I enjoy this thread.
I have a sickness.

 

me too!!
Which is weird because I don't like pickup trucks, and I don't like old vehicles.
But I can't halt the desire to have a vantruck/ tran/ whatever.

 

"...replace both tanks outright…"
'S da ticket! 'change over valve' 1st, clean lines'n filters.
I think U said U got all electrics sorted already.
Easy w/bed off, no? (just did so w/'80 F250)…
boy R there alota change over valves listed 4 them.

 

Ladies and gentlemen,




Took 4 of us about 6 hours to fabricate the new bed rails, rig it up, test the fit, edit the rails, test it again, edit some other parts... But it's bolted down solid now!

Needs a few frame spacers up front to line up the bodywork, but my nightmare is finally over.

Coming work: Detangling the wiring harness into the Ford F350 bed tail harness. I'll probably go bug the OBS sections of this site for info. Then I need to mount the replacement bumper, which needs its own brackets fabbed because of how the new bed sits.

Super exciting times!

 

Thanks Chris, do you know where the Centurion site is? I don't see it on FTE.

 

Hi Reno,
no it's not. Correct, but out on the web (sez 'site' not 'forum'), guys here hafta "squeeze into a different box" to get our fun in.
BTW: it's "Chad" not "chris"
ur lookin @ chrls & the 4th letter is L not an i, as in "Charles" Fuller. The ISP took all the vowels outta my name for the e-mail address. 'S OK tho, ur not the 1st...

 

My bad, Chad. The l looked like an i. That vowel tax is a mean thang.

I found these two but neither is active
Centurion SUV conversions
'89 Ford F-350 Centurion Conversion - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

I see complaints in there about the cobbled-on Bronco top leaking or cracking off. Maybe a Centurion isn't so desirable after all, when we can still find Excursions in great shape.