1997 Dodge Ram troubleshooting for not running vehicle

360MOPAR

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1997 DODGE RAM

Engine Performance problem
1997 Dodge Ram V8 Four Wheel Drive Automatic

I was driving my truck and the engine just cut-out.
Had it towed home and started a diagnostic on it.

Performed the following:
Checked all fuses and relays all good with the exception of a 5A Illum. Fuse inside the dash (not sure what that is). Fuse is not blown, just no power to it.

Check coil: good
replaced distributor cap and rotor, checked spark plug wires and spark to each plug with a check light: all good

had a P0123 code on my scanner, TPS, replaced it and it didnt cure the problem. No more codes on scanner.

Tried testing for fuel injector trigger pulse: No light when inserting checklite probe from neg. Ground to one terminal. However, had light from checklite when connected to positive and one terminal. Cranked engine and test light blinked.

Also fuel pump makes no noise when ignition switch is turned to ON.

Do I have a fuel pump problem or a PCM problem?
thanks

5 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Check fuse no.8 20amp in power distribution center and fuse no. 9 10amp in fuse block-if both okay and fuel pump w/n turn On-find the fuel pump connector and power the dark green wire from the battery positive post it should come on if the black ground wire is good. If the fuel pump comes on-test or replace the fuel pump relay-relay good -check the computer controlled of the fuel pump relay coil side

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Thursday, October 22nd, 2009 AT 4:16 PM

360MOPAR

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3 POSTS

Rasmataz,

Fuse no.8 20amp in PDC is good and fuse no.9 10 amp is also good. I also checked ASD and fuel pump relays they have good resistance (75 ohm as stated in repair manual) and they switch with power applied.

If I have power coming into the fuel pump connector (12v) and black wire has continuity, do I still need to apply power directly to the fuel pump?

You wrote: "If the fuel pump comes on-test or replace the fuel pump relay-relay good -check the computer controlled of the fuel pump relay coil side"

What does "check the computer cotrolled of the fuel pump relay coil side mean and how do I do that?

Also stated in my first message: I am not getting a negative ground to injector connector continuity. I found these instructions here on 2carpros. Com.

Thanks

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Thursday, October 22nd, 2009 AT 4:48 PM

RASMATAZ

MECHANIC
75,992 POSTS

Applying power to the fuel pump direct from the battery bypasses the fuel pump relay -if you have power to the fuel pump and a good ground it should come on both from the battery or its normal circuit.

The computer controlled of the relay is the coil side of the relay the computer powers the coil side to ground out the relay and power will be transfered by the switch side to the fuel pump

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Thursday, October 22nd, 2009 AT 4:56 PM

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OK, fuel pump has a good ground, hooked up power from battery straight to fuel pump and fuel pump is not working. So I will replace it.

Just one more question: the power coming from the dark green wire on the connector was 10.5 volts when cranking the engine.

Is this voltage drop normal?

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Friday, October 23rd, 2009 AT 6:21 PM

RASMATAZ