460/7.5 starting issue
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4th Gear
Joined: May 2026
Posts: 4
Likes: 1
460/7.5 starting issue
Hello, this is my first post on here. Just needing some guidance on an issue that’s been haunting me for a few weeks. My 460 is having an issue that’s similar to the symptoms of a bad distributor (starts, dies and runs longer when cold.) but the only variable that’s got me chasing my tail is relay 2 is chattering which is causing the solenoid in the transmission, and the fuel pump to do the same along with a popping noise coming from the distributor cap. I thought it was the PCM itself when I found blown caps on it, but I replaced them and same issue persists. I’ve tried the relay itself and some other small components. Any advice is greatly appreciated, thank you!
Hotshot
Joined: Jul 2020
Posts: 10,501
Likes: 2,651
From: Near Salt Lake City
You need to say what you are driving, and the locations of those grounds might be posted
I know what I am looking for and can find them on any Ford
Taurus is on the head of a 3.0
Yours will be on the fender apron or the radiator support, 2 black wires usually
I know what I am looking for and can find them on any Ford
Taurus is on the head of a 3.0
Yours will be on the fender apron or the radiator support, 2 black wires usually
Thread Starter
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4th Gear
Joined: May 2026
Posts: 4
Likes: 1
Yes sir I was able to verify the PCM ground is good. If I measure from relay 1 ground (PCM relay) to engine block ground I get a .001 v difference. If I measure from relay 2 ground (fuel pump relay, supposed to be grounded by the PCM) to engine block ground it measures 1.3 V of AC like it is oscillating. Also I skipped checking fuel pressure and such due to the fact that the issue occurs when the engine is not running and the key is set to run with just the electronics turned. I am thinking I have a bad PCM.
Hotshot
Joined: Jul 2020
Posts: 10,501
Likes: 2,651
From: Near Salt Lake City
Youn still need to check the fuel pressure to see where it is
You can bypass the processor controlling the pump by jumping the self test connector
Do that while monitoring the fuel pressure and see what it does when it dies
If the fuel pump is no good, the relay will click in and click out as it tries to fire it
Swap the relay, test the pressure, jump the self connector is where I'd start
You can bypass the processor controlling the pump by jumping the self test connector
Do that while monitoring the fuel pressure and see what it does when it dies
If the fuel pump is no good, the relay will click in and click out as it tries to fire it
Swap the relay, test the pressure, jump the self connector is where I'd start
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Thread Starter
|
4th Gear
Joined: May 2026
Posts: 4
Likes: 1
Youn still need to check the fuel pressure to see where it is
You can bypass the processor controlling the pump by jumping the self test connector
Do that while monitoring the fuel pressure and see what it does when it dies
If the fuel pump is no good, the relay will click in and click out as it tries to fire it
Swap the relay, test the pressure, jump the self connector is where I'd start
You can bypass the processor controlling the pump by jumping the self test connector
Do that while monitoring the fuel pressure and see what it does when it dies
If the fuel pump is no good, the relay will click in and click out as it tries to fire it
Swap the relay, test the pressure, jump the self connector is where I'd start
I ended putting a new PCM in and it’s running now no problem. Thanks for your insight
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