Just wondering if anyone had a fuel pump wiring schematic for the 98 Blazer LS 4 Dr. 4.3 litre V6
I thought fuel pumps ran off 12 volts at least. I cannot get a reading over 5 volts no matter what plug terminals i connect to.
Meanwhile the pump will not start up at all.
Obviously a fuse is not blown but,..... should I be replacing the oil pressure sending unit??

Thanks

 

You are testing the wrong wires. The fuel level sending unit operates on a +5V reference from the PCM.

As far as a schematic goes, I know I have posted it in the past. If I get more time, I'll try to find it for you or maybe someone else will.

 

Keep in mind that the grey wire at the fuel pump harness connector only has battery voltage for 2 to 3 seconds when the ignition is in the run position. It should have battery voltage constantly with the ignition switch in the start position. The oil pressure switch only provides voltage to the fuel pump when the oil pressure is above approximately 7psi, (probably not your problem). Just ahead of the fuel pump relay, in the underhood fuse panel, there is an empty, single terminal. That terminal runs directly to the fuel pump and can be used for applying voltage to the pump for testing purposes.

 

Hey Captain,
That is a good bit of info pertaining to the voltage time factor.
I'll just get the new pump inand connected and see what happens.
Thanks!
On the joke topic,.....have you heard this one?:

A Penguin was driving a Blazer and, having some mechanical issues, decided to pull into a garage for a diagnosis.
Leaving the vehicle there he saw an ice cream palour across the way and decided to waddle over and have a vanilla cone.
Coming back to the garage and having no hands the poor little guy got the ice cream all over his beak and face.
He then met the mechanic who exclaimed,
"Looks like you blew a seal"!
"No, no" said the Penguin, "It's just a little ice cream"!