Well, IF my truck got to the point that, I'd think about installing a boat prime bulb to keep it going, I'd suspect tank troubles.

These truck tanks have been known for the pick up tube to get rusted out holes in it that cause the same trouble your having.

You could cut your in cabin hard tank gas line an add in a clear piece of 3/8" tubing to see when it has no gas in it. This will also tell you it's time to replace the tank.

So the fix could be one of two ways 1. keep the tank full
or buy a new tank.
Orich

 

Priming bulb ordered. I'll have to think about adding a clear tube at the tank to help with diagnostics. I use a clear filter under the hood (mounted above master cylinder to view easily), but discovered the fuel pump can stop running and that filter still looks full.

 

Sounds to me like the problem is in the tank. The 1st 3/4 of the tank is fine and when it gets to a certain level it cuts out. I've never peeked down inside an in-cab tank so I don't know what the fuel intake looks like. Is there a bunch of crud on the bottom of your tank? Maybe sloshing a bunch of condensed crud is temporarily plugging that intake. When you changed the fuel filter did the old one have signs of this crud?

 

I haven't looked in the tank, either. But the last time I changed the filter, I didn't see signs of some nasty stuff.

I ordered new Wix filters. This weekend I hope to swap filters and dissect/inspect the old one.

 

If it were mine I would drain the gas out and look inside there some how or remove that tank and flush it out. You're 1st post #1 you also mentioned 1/4 tank. So the "tank" has the same gas level when the problem rears it's ugly head. And we have to wonder why the PO installed that electric fuel pump. Was he trying to Band-Aid the problem you are now experiencing? I'd bet a on it.

 

Well, the bulb pump arrived. I am impressed by the quality, as most seem to be pretty sketchy.

I put a clear container under the fuel line when I cut it open to install the bulb. The fuel that came out looked more like orange drink than gas. I'm guessing I dislodged some blob of Nixon-era varnish.

Once I burn the tank down, I'll try a couple rounds of fuel cleaner.

New filter shows being nearly full, where the old would just be half full. Must be flowing better already.

 

He did say it did this at a fill tank once also.
You said you replaced the sender/pickup so thinking no rust holes to suck air and happened once almost full tank.


Being you got poor looking fuel out and you said may have crud inside the tank I am thinking a sheet of "crud" fell off the side of the tank and covers the pickup and cuts fuel pickup. Motor dies no more sucking and the "curd" falls away from the pick up.


Could also be someone put a plastic bag or (used?) rubber in the tank and does the same thing as the floating "crud".
I say look in the tank to see what you have.
Dave ----

 

Drain and pull the tank. Take it to a radiator shop for a dip and start over with lines and filters.

 

The tank pickup tubes our non replaceable if you look at yours, and a filter sock on the tip of the pickup tube in the bottom of the tank which can rot away over the yrs.

I seen rusty gas look like what's in the cup.
Orich

 

Did I not read the OP right that he replaced the pickup/sender. Even if he replaced it say 5 or even 10 years ago I can not see it rusting thru that fast.
He also said it happened 1 time with a full tank besides a few time with 1/4 tank.


I have seen plastic bags get cough on the pickup with full or 1/4 tank and why he needs to pull the tank to see what the inside looks like.
Dave ----

 

I thought OP said it ran great at full tank. Then crapped out again at 1/4.
Edit. Nope You were right. There was one time it stalled with a full tank.

 

I have the same problem running out of gas and the tank is 1/4 full.

I have 2 thoughts rusted pickup tube with a pin hole that sucks air at 1/4 tank or floating crud blocks the pick up tube

Bottom line first
Theory (I haven't done this yet) Drill out the 5/16 flaring at the top of the pick up tube let the tube drop to the bottom. Remove the sender unit and fish it out with a telescoping magnet, the kind you get from Horrible Freight. replace the tube with a pre flared tube from NAPA or make my own out of copper.

DRAIN THE TANK:
I would drain the tank with a $12 impulse electric fuel pump. The kind you find on eBay. I ruined a pump yesterday by not having a filter before the pump and a chunk of crud got sucked into the diaphragm. I use about 8 feet of 1/4 in clear PVC tube (4 feet on in/out sides) so I can watch the gas flow I have a 30 in piece of steel brake line shoved into the clear PVC so I can go down the filler neck directly to the bottom of the tank. I transfer the gas to my other vehicle or a gas can. I like those clear glass cleanable filters so I can see the crud build up. NAPA sells them for abt $11

Note; I solder about 10 feet of wire onto the fuel pump leads and cover the connections with heat shrink to avoid sparks. Then I set the fuel pump on a stool between cars and tape the pump to the stool so it wont vibrate off the stool fall on the ground, pull the hose out of the tank and have fuel pumping all over the driveway. I also use a small 12 V battery 10 feet away, with alligator clips so if anything gets funny I can disconnect quickly. I also have 2 fire extinguishers handy just in case. I have transferred gas between cars this way 5 times now without accident. but I am very respectful of what catastrophe could happen so I'm careful.

Once the tank is empty, I'll take my air compressor hose and put that down the filler neck to blow air inside and totally dry the tank else it is still a bomb.

If I shine a light down the sender hole inside and see rust and crud I might remove the tank flush it out with Super Clean then dump a couple a gallons of ZEP Calcium Lime and Rust remover its like brand name CLR but cheaper. A gallon is $12. I get it at Walmart in the toilet cleaning/Janitorial section. Leave the ZEP /CLR in a couple a days then flush the tank.

One other Idea I had was instead of drilling or unsoldering the pick up tube was drain the tank dry, mix up some JB weld, use a 22 rifle cleaning kit with a patch wad and coat the inside of the tube with JB weld epoxy. Who Knows it might work.

EDIT:
Ok, I drained the tank I took the gauge sender out and peeked inside. The pickup tube goes straight down and bends toward the front so as to be about 1/2 in off the lowest part of the tank So my Ideas above wouldn't have worked so well. The tube was in good shape except for the very end. There is a big ugly mushroom of rust growing there, and, don't ask me why but, there were white paint chips and leaf looking floaties down at the bottom. All I know was this was a Orchard truck from Galt CA and sat for years.

I have it soaking in Super Clean now. After a rinse then some CLR to eat the rust.

LOL no wonder my fuel gauge didn't work. The float split and fell in the bottom of the tank.

 

Ok after the tank clean Nothing changed dramatically.

Just to be clear I have a 1972 302 with a Edlebrock 1405 and a New Carter vane pump and behind the seat stock tank. The brand new Carter pump was to replace a cheapo $15 chinese pulse pump I thought had failed.

The reason why I went electric is; the timing gear on the motor rebuild was from a newer 79-85 ford 302 (I'm unsure of the date) . Anyay the Mechanical pump had the same problem. Starving for fuel. I thought it was because the elliptical fuel pump cam was smaller.

I have a glass "see through" tube filter at the Edlebrock 1405 that has rarely gotten full there is always air in the glass even though it runs well.

I have a "see through" glass filter at the inlet of the new Carter vane pump and it is seeing air bubbles despite all new hoses and clamps.

I didn't put Teflon tape or paste on the compression fitting to the tank I did use a stick of copper Anti Seize on the treads because it was the only thing I could find that might be a tread sealer.

Its got me stumped.

All I can think of is The Air leak has got to be the compression fitting or the "see Trough" glass filter. I'm hating life right now

I so want a new 22 gal belly tank. $260

I think its the high suction required to get out of the top of the tank. At a lower suction point might make a difference like Chevy uses. IDK.


I started the the engine after the tank clean, and even though the glass filter @ the carb was bubbling 1/8 full it ran (high Idle) really well for for a full hour. I called it good and shut it off.

PS: the cheapo $15 pulse fuel pump did have a period where it filled the glass filter 80-90%. IDK waht happened? Maybe it's the elections IDK. Or it could be too many cheapo hose clamps. I'll check that tomorrow.

EMERGENCY:
I have a dump run I really need to make The bed is 3/4 full of dead asphalt shingles and the rear springs are flat on the axle bumpers, then THIS happens. ::Sheesh:: It ran Great for weeks!!!

I think I'll buy a DODGE. Just kidding I love FORDs just not right now.

 

Maclif, You should have a filter before the pump. I used an Atwood water / fuel seperator that I bought at Walmart. Mounted it inside the frame under the cab.

 

Oh those glass tube filters, I had more problems with. I won't use due to the same thing that your going through.

A guy, I once worked for had one of those glass filter on a old ford truck cherry picker 60's truck that sometimes it would keep running then other times it would act like it ran out of gas, which it did until we'd have to open the filter and re-prime by bleeding the air out.

But their was other times it would keep running. Sometimes this would happed 3-4 time with in 2 miles before would like finally catch on an work out all the air it seem to have in the line.

I can't remember if it had a manual or electric pump but we never know if it was going to run for very long with out it running out of gas that showed air each time in the filter.

Back in the 70's, I put one on a Chevy that, I had that was ran okay but it never filled the filter and always had an vacuum/air bubble in it. I remember, I changed it out cause it was starting to leak at the end O-ring.

Had a girl friend that had a VW bug with one on it and started having stalling issues which had one of those glass filters on it that had about 80% of air bubble in it.
I replaced it with a plastic one that also showed air but much less but her stalling issues when away.

I know those our one way filters like all filters but have never seen a glass filter full with out air bubble trapped in them. Plus they don't filter out that great like a paper core filters do.

I see a lot of those glass filters on many of the junk vehicles in the PnP junk Yds. that always gives me a flash back to the boom truck that had much gas pickup troubles with the glass tube filter.

But, I feel your pain!
Orich