1996 jimmy won,t start

[jerry5710]

i have a 1996 gmc jimmy 4.3 vortec cpi
went to store ran fine came home cut it off.
went to start it up the next morning it tried to start first
few turns of the starter then just went to spinng over but
would not start. spray ethier in it it will try to start.
check voltage at fuel pump. wire that plugs to pump.
one has week voltage assume that it is the fuel gage.
the other one will not get voltage with just the switch in the on position
but when you turn key to sart position it has voltage and keeps voltage.
is this normal

[old_master]

Grey wire at the pump should have battery voltage for 2 to 3 seconds after the ignition switch is turned to the RUN position. It should have battery voltage continously when the ignition is in the START position. Make sure the black (ground) wire has less than 5 ohms resistance to ground.

Sounds like a fuel pressure problem, have you checked it along with leakdown?

[jerry5710]

thanks old master for the reply.
i took the pump off and the two wires that run to the pump motor the grey and black wire that feed it and hooked a positive wire to the grey wire and ground to the black it still would not run so i think it is the pump.reversed them to positive to the black and ground to the grey. i know this is not a good way to check it but i knew if it would not run hooking strait to a battery that it was probly the pump. again thanks for the reply

[old_master]

That's a perfect test! The pump needs replacement. Be sure to replace the fuel filter also, it's located midship, inside the left frame rail.

[jerry5710]

hey old master
that did the trick put new fuel pump
started right up.


thanks for the help

[old_master]

Glad you got her going!

[momloony]

1996 jimmy replaced fuel pump and drove all day ran out of gas put gas in it now wont start

[momloony]

Originally Posted by momloony

1996 jimmy replaced fuel pump and drove all day ran out of gas put gas in it now wont start

what do we do now

[jerry5710]

Originally Posted by momloony

1996 jimmy replaced fuel pump and drove all day ran out of gas put gas in it now wont start

[quote] how much gas did you put back in it,can you hear the fuel pump
running when you turn the key on will run about 2 or 3 seconds and then stop.if you can hear the pump run then put a little more gas in the tank and turn the key on and off in ten second intervals don;t start it just turn the key on and off a bout ten times and then try and start it

[HeavyChevy82]

Originally Posted by momloony

1996 jimmy replaced fuel pump and drove all day ran out of gas put gas in it now wont start

You should fill up before you run past 1/4 of a tank. These fuel pumps are cooled by the gas that’s in your tank. When you run them empty you overheat the fuel pump and could potentially destroy it. I've seen a lot of dead blazers at the gas pump after someone has heated up the fuel pump and then dumped cold gas in to the tank and seized it up.

[old_master]

Overheating of the fuel pump is a myth, here's why: The fuel pump motor is mounted in a "well" inside the fuel pump module. The fuel return line empties fuel directly into the "well". While the engine is running, fuel is constantly being circulated to keep the pump cool. When the "well" overflows, the excess fuel spills into the tank. The pump picks up fuel through a filter located outside the "well". When the fuel pump can no longer suck fuel from the tank, the engine stalls, 2 to 3 seconds later, the fuel pump relay shuts off the fuel pump. Running the tank low on fuel increases the concentration of contaminants that may be in the tank, and the risk of clogging the in-tank filter increases.