GMC Repair: 1994 GMC Jimmy, fuel system treatment, fuel pump relay

Question
I have a 1994 S15 Jimmy with the 4.3L Vortec engine and Auto trans. It has 99K miles. My problem is that starting 2 weeks ago as I was driving, the engine just cut out in the middle of a turn through an intersection. No rough running or idling or anything like that, it just stopped. When I tried to start it again it would crank over but just wouldn't fire up. A local garage check the fuel pump relay, fuses, grounds, etc and couldn't figure out the problem. I replaced the fuel pump relay with no luck. After the garage had checked everything the truck just started one day. I took it home and it died the same way later that night. This same process repeated again with another local garage. Now the truck is in my driveway after dying again and I can only think maybe the fuel pump? I also added some Slick 50 fuel system treatment to the tank about a week before it died the first time, but ruled that out as I only put half the bottle in a full tank. Please let me know if you have an idea or have experienced anything like this before. Thank you.

Answer
Hi Matt
Get the garages to check fuel pressure.
It should be 55-61 psi. Anything less and it will stall and or not start.
Are you sure it is firing? Is it loosing fire or fuel do you know?
These particular engines are VERY picky about fuel pressure.
Have them check fuel pressure if possible when it starts and runs and also when it will not start.
I hope this helps.
Just advice from experience.
Good Luck
Pawl