1995 gmc sonoma no start cranks has spark

[Jweave]

I own a 1995 gmc sonoma and it left me sit earlier today. After working on it for awhile I discovered a few problems. The motor had no spark or fuel, I figured out the coil was bad and now it has spark and it starts on starting fluid but the tbi injectors aren't spraying. The fuel pump does prime but we aren't sure of how much pressure it's building. We put in new injectors and cleaned the entire throttle body and fuel is making it to the injectors but the injectors don't fire. Any ideas? Do the injectors require the 12 psi of fuel pressure in order to fire or is there another problem? 

[davester]

I don't know the details of earlier generation fuel injection systems, but I would expect they would need approximately what the GMT800 engines need, which is 55-60 psi to spray properly.  Carbs are in the 5-10 psi range (enough to get to the carb, not enough to force open the float).  You might check that the injectors are getting a signal for when to fire (it is likely pwm, don't know the max voltage).

[Niners 365]

   Have you replaced all spark plugs and wires? If you haven't then I recommend you do. Don't go with the typical 6mm wires, go with the 7.5 to 8mm spark wires. The start fluid will start at a lower spark rate then the injectors. If that doesn't solve your problem then it is your fuel pump. Your going to need to replace it as well as the fuel filter. There is a video on YouTube shows how to replace the fuel pump by taking off the bed of truck, this is way easier than dropping the tank. 

 

 

[Jweave]

5 hours ago, davester said:

I don't know the details of earlier generation fuel injection systems, but I would expect they would need approximately what the GMT800 engines need, which is 55-60 psi to spray properly.  Carbs are in the 5-10 psi range (enough to get to the carb, not enough to force open the float).  You might check that the injectors are getting a signal for when to fire (it is likely pwm, don't know the max voltage).

No, these tbi trucks only require 12 psi of fuel pressure to run and I think my problem is electrical 

[Jweave]

4 hours ago, Niners 365 said:

   Have you replaced all spark plugs and wires? If you haven't then I recommend you do. Don't go with the typical 6mm wires, go with the 7.5 to 8mm spark wires. The start fluid will start at a lower spark rate then the injectors. If that doesn't solve your problem then it is your fuel pump. Your going to need to replace it as well as the fuel filter. There is a video on YouTube shows how to replace the fuel pump by taking off the bed of truck, this is way easier than dropping the tank. 

 

 

Spark plugs aren't the problem. Tbe injectors don't spray fuel and we need to know why. The fuel pump is delivering fuel just fine right to the injectors. 

[Niners 365]

 What size engine is it? The 2.8 V6 or the 4.3 by? Also is this a throttle body injector? Meaning you have the 1st generation of injector that still sprays into the carburetor? If your not getting spray at the injector, then you have problem either with cloged injector, or the voltage is gone for them to work. Check and replace fuses associated, and recommend you try replacing the entire injector. I had the issue with my 4.3 by but it's a 2003 with the spider injectors. It had something to do with the heads clogged and the injectors were worn.