DaEvil

iTrader: (1)

I hope this is the correct forum to post ? anyway I have a 73 Datsun with a 2000 LS1 and its been running fine until yesterday . I go to start it and it only cranks over .I don't hear the fuel pump come on so I put 12v to the pump and it works . Next I replaced the 5170 relay but still no pump when I turn the key . Can anyone suggest what I should try next ?
Thanks in advance

ls1nova71

iTrader: (4)

Check all your harness fuses, and if they're all good, start checking grounds. Most problems people seem to have is with bad grounds. Is this a car that has been running for a while or a project that you just started?

i r teh noobz

iTrader: (4)

Check for the PCM signal at the relay. If the PCM isn't providing your pump relay with an activation signal, then check the PCM's ign/run/crank voltage reference.

From LT1swap.com:

Pin 9 - Dk Green/White - Fuel Pump Relay Control - This wire the PCM supplies 12v+ to control a relay for fuel pump. PCM will turn on the fuel pump for 2 seconds at initial key on. When the engine cranks or starts, the fuel pump will then continue to run, untill the engine stops, or you shut off the key.

Make sure that wire has power when you cycle the key.

DaEvil

iTrader: (1)

there is no signal to the relay, I swapped in another ECM and still no signal . Where do I go from here ?

DaEvil

iTrader: (1)

[QUOTE=i r teh noobz;17165957]Check for the PCM signal at the relay. If the PCM isn't providing your pump relay with an activation signal, then check the PCM's ign/run/crank voltage reference.

How or where do I do that : )

psiconversion

iTrader: (5)

Check for Ground at positions 1 and 40 on both PCM connectors.

Jon
Psi

i r teh noobz

iTrader: (4)

To check for the PCM signal, check that the wire going from the PCM to the control side of your fuel pump relay provides a full 12v when the key is on (2 seconds) or cranking.

If the PCM does NOT provide the 12v, make sure that the PCM has all power and ground connections and that no fuses are blown.




Does the car start if you manually activate the fuel pump?

DaEvil

iTrader: (1)

No the car does not start if i manually activate the fuel pump

i r teh noobz

iTrader: (4)

Then the fuel pump not working is likely just another symptom of the problem.

I suspect that your PCM may be losing its ign/crank reference. I forget what pins it uses, but there should be one or two wires that provide 12v to the PCM to tell it that the key is on. Make sure those are providing the proper signal.

Did you check the PCM constant power and grounds yet?

You can check for spark and injector pulse to help isolate the issue.

DaEvil

iTrader: (1)

I jumped the p[ink wire 19 and the fuel pump comes on for a short time but still no start