Anyway, now it won't start. Cranks fine and has spark but no fuel. There are
three relays I can see under the hood. Does anyone know which one is the fuel
pump relay ?

Does the vehicle have an inertial switch around the vicinity of the fuel pump?

Don't know about GM, but plenty of Ford vehicles have an intertial circuit
breaker which, when tripped, cuts off the power to the fuel pump. This is
supposed to keep fuel from pumping when there is a leak in the system caused by
a vehicle crash, but these breakers can trip if you hit a bump hard enough and
so on.

Also, check the ECU (or ECM) and see if the wiring harness connection is good
and tight. Sometimes, an intermittent connection can cause problems.

Another would be to have the vehicle scanned for codes to see if the computer
is detecting a problem.

And, you could even try to see if the suspect relay is at fault. See if repair
is possible. If not sure, replace it.

I remember when my friend who has a Honda Civic was trying to figure out why
his relay module for the fuel pump was not triggering and moving the fuel. He
was contemplating replacing the relay module, which would've fixed the problem.


However, I discovered that his bad relay module had a few distinct cold solder
joints in the circuit. Reflowed the joints with new solder and the relay was
as good as new. While replacing the module would've work, it was much cheaper
to repair the old module. And, considering that I was friends with this guy,
he didn't have to pay anything except a couple of beers for a job well done.

I'm leaning away from the pump itself because there were absolutely no
problems
with engine performance, it ran like a raped ape. It kept it up after a long
run too, after the tranny was fixed of course.

You never know. It could very well be the fuel pump. However, it is good
practice to check the simple stuff first when troubleshooting, as well as
having good deduction and process of elimination.

One thing that may help is to obtain some service book for the truck, like a
Haynes or, even better, a Chilton's. Or, and I recommend this, find and buy a
copy of the Goodwrench factory service manual for your particular vehicle. The
Haynes and Chilton's books should be available at your auto parts store. The
Goodwrench service literature might be available for order from General Motors
at your Chevrolet (Blazer model), GMC (Jimmy model), or Oldsmobile (Bravada
model) dealerships or Goodwrench parts and service departments (doubtful, but
it's worth a try) or you can try to see if any are up for bids on eBay. -
Reinhart