Truck Repair: truck wont start when hot, tank unit, full tank

Question
I have a 1989 chevy 1/2 ton 4x4 with a 350 motor.
It runs great. Yesterday after stopping at the bank, when I came back out to leave it would not start.It turns over great so I put a splash of gas in the carb and it fired up and ran for a few seconds. I did this three times and assumed the fuel pump was probably bad. I towed it home and out of curiousity I tried starting it again and it fired right up. It was about 2 hours from the time it died until it started up again.
any ideas what is going on?

 thanks bobb

Answer
Hi Bobb,
Possibly could be the fuel pump.
When you turn the key to run, the fuel pump should run inside the tank for two to three seconds. You should be able to hear it.
As the ecm recieves a crank signal, it then keeps the fuel pump running.
A common test for a bad fuel pump is if you don't hear it running when the key is turned on, slide under the truck, and just as someone turns the key on, smack the bottom of the tank...just about under the center of it, with your hand....about as hard as you can with your palm.
Sometimes that will jar a pump into action.
It is entirely possible that you jared it loose while towing.

Now...if you do that, and it jars it into action....you can't count on it working every time.
What you can count on is that you will be in there replacing that pump before long.

Here is something that also needs checked if you replace the pump. I have seen the wires inside the tank...where they connect from the pump to the bottom of the tank unit, actually loose on the rivets. Make sure they are tight.

As for getting in there....it is often easier to unbolt the bed, and with a few helpers, lift it and move it a couple feet to the rear.  Not nearly as hard as dropping a full tank, if the rust under your truck isn't too bad.

Van