Help! Problems with my '88
 

Riddle time! The other day I started my truck to let it warm up before work. When I went out 20 minutes later it wasn't running and the battery was dead. Immediately I'm thinking alternator. I pull the alternator, recharge the battery and it starts just fine. I didn't let it run long as there was no belt on it, I just wanted to verify that it would in fact start with a charged battery. So I took my alternator to O'reilly's where it tested good but made odd noises on the tester.

Because of the noises, despite the test results I bought a replacement with a lifetime warranty. I figure the bearing may be going and it tests good but after it heats up it stops producing electricity. A slight grasp at straws I know.

I get home and replace the alternator and put a new belt on and make sure all contacts are clean, shoot the battery which is pushing 12.8 volts, and make sure connectors are seated. To my dismay the engine just cranks when I turn the key. It isn't sluggish or struggling. It just won't start. I pulled a spark plug and verified that the plugs are receiving power.

So to me this suggests either a timing issue or a fuel issue. Both would seem like odd coincidences given the circumstances that seem to point to the alternator. Anyhow, anyone who has any input or experience with an issue like this please help me. I am closer than I have ever been to seeing just how long a pickup truck will burn with dual tanks completely full of gasoline. Thanks in advance.

Todd

Given your spark verification, suggest if it were a timing issue, there would be misfires happening after being cranked over for a while - so I'm initially leaning towards a fuel issue.
When you roll the key to On, do you hear the fuel pump run for its 2-second cycle? Unless your vehicle has been 'upgraded' - you have a low pressure pump in each tank and a high pressure pump along the frame rail about directly under the driver side floorpan. May try switching tanks to see if the assumed fuel issue changes...?
Good luck, and keep us posted.

Listen for fuel pump and check fuel pressure at the Schrader valve.