Good afternoon.

Been trolling threads last week or so trying to diagnose this problem. Not much in tools or testing equipment, and financially strapped for new parts. Hoping to find fault, and bypass it if possible. Any help would be appreciated. Its a 1979 van. Has the 351 in it. Not sure what else I would need to supply info wise.
Some coolant loss, temp gauge pegs out, then cools off and maintains mid gauge.. maybe higher. I assume thermostat sticking, or higher than rec. temp. Neither fuel gauge works correct and MPG seems too low.

Incidents....

Aquired with front tank 1/8th, rear empty, 6-8 miles and started cutting out. Stopped and idled a few, then 15 miles ok. Cooled complete,went 15 miles, cut out again. turned off 5-10 min, drove a mile ....repeat till home. Gas was low. Added more.
Was fine for a week then stalled ..wouldnt start. I added gas, knowing it had some... wouldnt start. Direct fed carb gas from bottle. It started, and then ran fine again. Filled front tank first then back. After a couple dollars it over fills... I made sure back tank was empty prior to this .. so how full? Drove about 60 miles on back tank. Went back to front tank.
Stalls sometimes but usually starts. Always at operating temp. Yesterday made 2 trips(6 miles each). Required bottle gas to get running. Last night it stopped running altogether cold. Will run on bottle gas, but wont cont. I know there is a least a few gallons of gas in front tank.

Thanks in advance.

 

This vehicle is carburated. In continued digging, I assume the following...

Carburated has manual fuel pump, and not in either tank.... and have ruled it out for now as it is manual and should fail or nor fail vs intermittant..... I would pull from carb, but if no gas caused do to air leak in rubber hose, or clogged tank components wouldnt this be a false read?

If fuel sector solenoid is bad it could stick in one position.. possibly defaulting to main (rear ...as near as I can tell). If so .. I wonder if I can add gas to rear tank, and it would then start up? I just did this and indeed it did run. also used voltmeter and valve is getting power in one switch position only. leads me to believ it is good.

Dash switch going bad shouldnt cause what I am experiencing.
Wondering if I can verify this by voltmeter or pulling apart and bypassing switch for testing purposes. Doing this would activate solenoid in one position only (main tank)? added voltmeter to back of switch connectors with key on, and off. power does change. i am colorblind so the wiring colors are killing me. I believe this switch to be working.

I show no carburator filter, and getting ready to change fuel filter to rule that out.

Other than this ... I ruled out dynamark .. as I get spark even after it stalls out with no cooling time.

This leavs me with fuel filter, tank components, and rubber lines.

Could someone please advise me if my thinking and testing is accurate, and sound.

 

I am getting desperate.. lol. really need this vehicle for work in AM. even more though I need it to be reliable.

Didnt know how to bump my post as this is my first ever forum. I apologize if I have violated any ettiquete rules. Have been reading in here for hours. Kind of have information overload.

Thanks