So I might as well start off by saying I'm not typically a Ford guy mainly due to a bad past with a certain ranger that still haunts me. I do however work on them on occasion for certain people. A guy pulled this jewel out of a pecan orchard a while back and asked me to get it road worthy for him. He had no idea what he was getting into and 3/4 of the way through a top to bottom and front to back upgrade he gave up on me and the truck became mine because he still owed me some money. My issue is with the fuel system which is almost completely new. Both tanks replaced, ask three fuel pumps replaced, also pressure regulator and relay and filter. For the life of me I cannot get good fuel pressure to hold in that system. Once the truck chugs to life it runs great but getting it to start is insanity every time. I've put clear lines in several sections to see what the fuel is doing and the stock style pumps kept leaking fuel back to the tanks even when they were supposed to have check valves in them. An edelbrock micro pump wouldn't even build pressure. After it gets to running it holds pressure fine but cranking pressure takes a bunch of key switching on and off to build. Any knowledge is a great help at this point because I'm almost to the rag in both gas tanks point.

 

I suspect the fuel delivery module is your headache
That is where the 4 lines come in, 2 lines come out.
It's function is to keep the fuel going back into the tank it's going out of.
There are a set of check valves in there that get corroded over time, and if it sat, they probably are stuck fast. Sadly they are not rebuildable.
They are only on the 3 pump system, 85-89.
After that they put a check valve in the fuel pump module in the tank.
Here is one on Ebay
https://www.ebay.com/p/F1uz9b263b-R...-OEM-Ford/10017006698?iid=152731120624&chn=ps

Here is what it looks like inside #ad
#ad
#ad

 

^^^what that semi smart feller said^^^
an easy way to test if it is in fact the module is to bypass it and only run one tank.
i replaced the module on a 87 150 with a manual tank selector valve around 20 years ago due to the cost of the proper valve.

 

That $177 price on the one I posted is cheap. The last one I bought was around $200
I went through 3 in 500,000 miles on my 89 f 350

 

I thought you named me fart smeller??????
Change your mind again ? Or did the old timers kick in...….

 

i was being nice so as not to skare the new guy away on his first post ya paste eating window licker!!!