My experience has been that its located in the left side of the block (looking into the engine compartment), below and behind the intake manifold. Its a little hard to find but it'll have a black cap that looks similar to the A/C cap.

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Sorry for the delayed response 2002GMSONOMA. I have been beyond the grid. I definetely do not have a Shrader valve. I spliced in a tee at the fuel tank (PO cut out an access panel in the bed) and checked pressure. Pressure held for almost an hour at 47 psi and only dropped a few pounds afterword. I am starting to think my timing chain may be the culprit of the horrid rough running. I have been through the fuel system (rebuilt injectors and replaced pressure regulator, new fuel pump, new filter, and holds pressure.) good spark on all cylinders, and 180 compression on all cylinders. I am not sure where to go from here.

 

Is there a fuel shrader valve on an '88 chevy suburban with a 350 V8

 

Not a permanently installed one. See my other reply to your question.