trying to measure voltage, on fuel assembly wires.

HELP!!!!!!!!!!!!!!!!!!!!!

my tank is hanging down, the weather is nice,
want to know if its just the wiring, or if i need a pump too?

originally was only getting 10lbs pressure, but was still able to drive it (slowly and after restarting several times) to Autozone to have the pressure checked... (10 lbs)
while dropping tank, I noticed the wire harness was crushed between tank & frame.
apparently the original plug had failed, and someone else (i.e the previous owner) replaced it, so it's been spliced.

trying to confirm its not bad wiring 1st, before i buy a new pump, and be bummed, because the wiring was just bad.

 

Was trying to figure out which were the power wires to the tank...
Heres the scematic, i found that, for the whole vehical. to whom it may concern...
it did get what i was looking for, at the time, but it didn't answer my voltage question...

the 3 prong plug; is the "Fuel Tank Vapor Pressure Sensor".
(black, grey, dark-green)

the 4 prong plug;
the "pump motor" (grey & black),
and the (purple and the other black) are for the "gauge".

measuring voltage.........

 

Still Guessing...

when i 1st turn the key on;
i get 12v for about 2 seconds, then it drops to (.000).
shouldn't it remain at 12 volts...???

neither plug was plugged into the tank, when i tested it..?

I did NOT get ground, on both black wires, just one... hmm...
i believe the scematic shows both blacks, as equal ground.

maybe because it doesnt detect fuel from the gauge, it kills the power?.. ive had gauge fail before without loosing the pump.
i cant imagine the "tank vapor pressure sensor" plug, would kill the power to the pump, just trigger a code..? right? no?

jeez, what a day... Hoping to here some good news from somebody here...

 

That's the fuel pump prime relay, it comes on for two seconds then off till you crank the motor.

 

Cool, thanks for the comformation...

 

The fuel pump grounds at the left rear corner of the frame. From the module connector to a good clean ground, resistance must be less than 5 ohms.

The fuel level sender grounds in the front of the vehicle. From the module connector to a good clean ground, resistance must be less than 5 ohms.

Something is screwy with your pressure tester. The poppet nozzles will not squirt fuel below ~43psi and the engine will not run.

 

thats why i was suspecting an intermittent wiring problem.

 

Sounds like you creating work for yourself. What problems are you having? Have you checked fuel pressure and leakdown at the service port next to the distributor? What is key ON, engine off, pump running fuel pressure? What is the pressure 10 minutes after the pump shuts off?

 

yes, near the distributor.
the guy from autozone, only ran the test once, it was at 10 lbs,
and he didnt even wait for the leak down, it didnt cost me anything.

i pressed the valvestem on the service port while it was running,
it barley pee'd out and inch, on to the plug wires, didnt even make it to the firewall.

 

Like I mentioned earlier, the engine will not run if pressure is below ~43psi... typical AZ stuff. Find another store that rents them and we can help you check the fuel delivery system.

Edit: Not a good idea to open the schrader while the engine is running.... raw fuel + sparks = fire