GMC Troubleshooting Questions? Ask a Mechanic for Answers
when it will shut off and not restart will it somewhat run on starting fluid ?
you can do that also
but we need to know if it will run on starting fluid or carb cleaner as its being sprayed into the engine
ok unplug the big fuel injector connector and with the key ON see if 8 terminals in the connector you unplugged show 12 volts
or use a noid light
or connect a test light with the test light clip to a good 12 volts do the other 8 blink your test light bulb when cranking it over ?
so it always has 8 blinking and 8 showing 12 volts and it will run when adding fuel ?
key ON engine OFF what is the fuel pressure ? and will it hold somewhat ?
is the fuel filter new ?
the problem we have is if you add fuel and it runs we know it is a fuel problem
the fuel pump spec is 60 - 66 PSI key ON engine OFF
since you have a good injector pulse this issue gets narrowed down to dirty fuel injectors or low fuel pressure
if you change the fuel filter will the pressure come up ?
see if the pressure comes up close to 60
if it does then does the problem go away or get alot better ?