Sitting for a long time? Start with the basics - clean your connections, including the grounds.

 

 

If you found a bad connection on the master cylinder then its just as likely your underside fuel pump connections have also suffered from this well known situation. A dryer climate like CA might delay connector corrosion its no guarantee even a small amount of humidity after 15 years hasn't brought this about. Basically any metal-to-metal electrical connection can be affected this way and its pretty common with any vehicle not driven in such a long time.

While there might not be a lot of visible rust/corrosion of the body/suspension parts the nature of vehicle electrical connectors makes them very susceptible to this condition---they're so small and can absorb moisture that never evaporates back out. Because the contacts are so small even a little corrosion can cause problems like you describe.

I once had an '88 E150 that was driven daily have a failed fuel pump connector without any warning. After a $450 tow bill the repair shop found the condition almost immediately, cleaned the connection, added a dab of dielectric grease and the van restarted immediately, It ran reliably for the next 4 years.

The individual connector pins can be cleaned very well using muriatic acid VERY CAREFULLY (with eye & skin protection!!!) with a cotton swab and applying it to the metal pins.

HTH

 

 

Yeah, that's what sitting will do for you.

 

Wow---those are some fuzzy lookin' parts!

Just curious if you're working from a schematic for these electrical issues? (I don't have any experience with multi-pump & tank set ups, just curious.)

 

 

I admire your willingness to dig into this problem without a schematic---I can't chance a tail lamp without one.

Unfortunately I'm not familiar with your fuel system and don't have any schematics for your year---I find those I need for Ford through eBay. Here's one for a 1986 E150/E250 you might consider having if you'll be keeping this van and DIY repairs.

You might also ask questions in the Electrical & Wiring Sub-Forum too---could be a lot of members there have the exact info or help you need. Link: Electrical Forums

HTH

 

You will only have power for one second each time the key is turned to the run position.
The EEC (PCM) grounds the fuel pump relay coil for one second to do this.
To trouble shoot the fuel pumps circuit you need to ground pin #6 of the self-test plug and turn the key to the run position.
If the fuel pumps run with pin #6 shorted you may have lost the small black wire with a green stripe ground wire at the NEG post of the battery.
If this ground wire is OK you may have a bad EEC (PCM) computer.

Attachment 277922

Attachment 284629


/

 

 

Your Fuel Tank Selector Valve has wires going to it???
Is this a Diesel?
If not what size engine do you have?
What are you calling the fuel pump relay switch?

 

 

Nothing looks stock for a 1987 5.0L E-150.
There are no wires going to the fuel tank selector valve on a stock van unless it had a 7.5L engine.
The fuel pump relay is not wired with those colors on a stock van.
The two red wires are in the wrong place on the relay socket to turn on the selected fuel pump on a stock van.

Someone has completely rewired the fuel system on this van, changed the type of fuel valve.
So without knowing how it is wired I can not help you any further.