UPDATE: Code 33 - no fuel - no start

[Texvet]

Happy Saturday All -
My 1992 SCLB 1500 5.7 700R4 2WD shut off - sputter and spitting to a stop. My friends a AAA brought me and "Ole Donnie" home.
First thing I did was check fuel pressure - nothing (0 psi). Pulled codes and got 33 MAP (manifold absolute pressure) sensor circuit high (low vacuum).
I am not sure if the 33 code is the result all the sputtering and spitting it stalled out? Or if it could be responsible for cutting off the fuel pump? The fuel pump and filter are about 8 months old.
Before I start throwing parts at it....
What do you think? Could the 33 trouble code be responsible for shutting off the fuel supply?
If not - I'm thinking it could be the fuel pump relay? The fuel pump fuse is not blown. But, I need to understand what roll the trouble 33 plays.

Please give it thinkin and let me know your thoughts.

 

[someotherguy]

The code won't cut out the fuel pump. Your pump is probably bad, or its power/ground have been damaged. The ground wire can break loose from its terminal where it attaches to the frame near the tank; have seen it numerous times.

You can power the pump as a test (through the circuit including the relay) by jumping +12V to the "G" terminal on your diag connector (bottom left pin, assuming your connector is oriented so that "A" is top right.)

Code 33 is probably being caused a vacuum leak to the MAP sensor; check the plastic tube connecting it to the rear of the TBI unit. The rubber boots often crack/get loose over the years. Bad vacuum signal to the MAP can cause too rich of a fuel mixture.

Richard

 

[Texvet]

Thanks for the info Richard,
I have a new Bosch pump sitting in the garage. Good to know I can easily test the pump through the OBD1 connector. I've heard of other ways to test with jumper wires. But, honestly I am not real comfortable dicking around with electricals (as in jumper wires and such). I have a Power Probe that I've never use. But I will use it to put 12V to terminal G to check the circuit to the pump.

Regarding the MAP sensor. If I don't see anything obvious w/ the vacuum hose or connection. I will wait until I restart and see if the SES light comes on. It wasn't on before this event.

BTW, I lived in Pearland for 12 years. I moved down there when it was starting to boom (1995). Moved back north in 08. I am sure it is a lot different today.

Thanks again for your advise.

 

[SUBURBAN5]

BTW, I lived in Pearland for 12 years. I moved down there when it was starting to boom (1995). Moved back north in 08. I am sure it is a lot different today.

Thanks again for your advise.

Yes its grown, very established now. (Parents live there) so I visit every so often. If you haven't visited it's easy to confuse the new roads.. 518 and 35 still easy to recognize. Sorry to butt in. Just when I saw pearland i had to throw my 2cents.

 

[Texvet]

Update: Well, I clearly got ahead of myself. The 1st thing I did when the truck was towed home was check for fuel pressure, When I didn't get any pressure. I stopped looking thinking I'd found the issue. To confirm the dead pump theory. I jumped pin G on the OBD1 port and still no pressure. So I installed a new pump. With all the excitment of having fixed the problem...

Now - it seems I have a no spark issue.

So - I will now start the painful quest of tracking down the cause of the no spark issue.

 

[Schurkey]

Finding a no-spark fault shouldn't be that tough. It's not much different than the old HEIs with the 4-pin modules, except that there's an ECM playing with the spark advance instead of weights, springs, and a vacuum advance canister.

No spark AND no fuel spray from the injectors? Pickup coil, Ignition module, or wiring harness between distributor and computer.

Fuel spray, but no spark? Ignition module, coil, or the wire harness between distributor and coil, or between coil and battery. Perhaps a failed coil wire. Defective cap 'n' rotor.