1994 S 10 wont start...two new fuel pumps

[starwc]

Hello

Have a 1994 S-10 Blazer 4.3 liter, with 240K miles. Was starting
some day not others. checked the fuses, relay and wiring
at relay and to the tank. replaced pump and filter...original pump had
burned wiring between harness and pump. Still would not
start. Took to mechanic who replaced the spider, regulator.
Ran for about 3 weeks ( pump from Auto Zone). Replaced
with 2 nd pump...ran for 3 days...stopped while setting at the
drive thur at Burger King... Have checked pump and it is
running during the prime circuit and when engine is cranking
over. Will run if I put gas into intake manifold. Mechanic says
I have an electrical problem...computers were checked...This is
the 4th pump in 6 years. Read that there is a gray wire
connection under the drivers seat that runs to the fuel
pump..and computer..which has caused this problem....any suggestions or
thoughts....I am stuck as to where to look. thanks

[speedzonwheels]

I have a 94 S10 Blazer with the Vortec also. I would check your fuel pressure. I have the same issue going on at the moment and I found out after replacing the Regulator and looking at the spider injectors that something else was going on also. So I been getting plenty of advice and first thing is to always put a fuel pressure gauge on your fuel rail and see if its holding pressure with the igntion flipped on and than flip it off and watch the gauge. If it drops, you have a leak. The way to test if its the fuel pump leaking is to pinch off the return line that is underneath your vehicle and near the fuel filter. There is a section of rubber fuel line there to pinch off. You can use a vice grips with a piece of cloth around the hose. If when you put the pressure gauge on and its not reading at minimum 55psi primed, than thats means your pump isn't pressurizing enough for it to start. My truck has the same sympton as your's does right now. I can start it with starter spray and it will fire right up, If i don't use any starter spray, it will never start. So I would first check that.

Than if your pressure is holding(leave it sit for atleast 10 minutes and see if it drops) and is high enough, check to make sure you have spark by putting an old sparkplug on a wire or a screwdriver can do the trick too if you hold it near the end of the wire.

[speedzonwheels]

Oh and forgot to tell you that if the fuel pump you are getting from autozone is not a bosch or ac delco pump. Those cheaper pumps are notorious for going out all the time on people and i picked up a bosch from advanced auto for $96.00 last night vrs $89.00 for the cheaper model. I called around and this was the best deal for a bosch pump.