Starting issue / running

[Morrisett]

Hey guys,
Recently did my first start a few weeks ago (can see link on previous post) but I only let it run for a short time 15 secs +/- since the cooling system wasn't fully plumbed. Now that I have everything plumbed and coolant added I am having an issue keeping it running more than 5-10secs. This doesn't appear to be present at the first start as it ran a short time longer without any issues.
Engine starts immediately without any hesitation but after a few seconds (5-10) it stumbles around and sounds like its starving for fuel. After it dies if I try to start it immediately it sputters and has trouble firing back up but if I cycle the key off and on once or twice I can hear the fuel pump prime and it starts again instantly. I have roughly 6 gallons of gas in the tank so I don't think that's it.
Only thing I can think that might have caused this is a had to weld a nut on the coolant cross over to get it loose (previous owner broke off the key hole). I did disconnect the main harness from the computer before welding but did not disconnect the main ground or positive from the battery? not sure if the short time welding damaged something? any ideas where to start? almost seems like the maybe the fuel pump isn't running after the car starts?? not sure it would run at all if that were the case though...
Don't see any sources of a vacuum leak.
I will check the fuel pressure this evening and see if that is fluctuate at all.

97 cobra DOHC donor engine- wire diet by Art
Engine ran fine in the donor vehicle so I know I started with a good working parts.

thanks for the help

[klawrence]

Is the fuel system return or returnless ?

[cob427sc]

Could it be the PATS anti-theft? I used a 2000 donor and it would not allow the injectors to fire without the ignition switch and key with a chip. I was told by a Ford engineer at the time to obtain a computer from a police cruiser as they did not have the PATS system. Fired up fine after the switch. Should be able to program out of the computer. I figured this out by spraying gas into the intake and could make it run. Then I listened for the injectors which made a click as they opened/shut and didn't hear anything as that was how the PATS system prevented the car from running.

[Morrisett]

Has a return

[Morrisett]

PATS was disassembled with the wire diet.

Getting somewhere…I am getting momentarily power at the fuel pump solenoid for the prime cycle but it’s dropping out after the initial start. Apparently Ford did some weird stuff and 96 through 98 with the prime cycle with one solenoid and then power supposed to jump in from another source to continue running the pump. Art is helping me run down so possibilities…

[klawrence]

ah good , was going to suggest running power to pump to see if it made a difference.

[CraigS]

I am not sure if the inertia switch kills all power or just running power to the pump but I'd check it to see if it has tripped.

[ggunter]

Always disconnect the battery when welding anywhere on the car and try to keep your ground lead close to where you are welding. I have had trucks that had the ecu blown because of back feed and manual transmissions that have had the shift rails weld themselves in the case trying to create a ground. Disconnect the battery always and if possible unplug ecu's.

[phileas_fogg]

I am not sure if the inertia switch kills all power or just running power to the pump but I'd check it to see if it has tripped.

Just the ground leg of fuel pump relay. I don't recall if RF wires the inertia switch on the trigger side or power side of the relay. The switch itself is rated to 20A (maybe 30A), & from another thread I learned that Ford wired the switch both ways in various years.


John

[Morrisett]

Thanks guys, inertia switch is on the positive side and it wasn't trip. I traced the problem back to the CCRM (bunch of relays inside a sealed housing that communicates with the PCM) and it appears the fuel pump relay is not staying on... just momentariy. Also ran a 12v to the fuel pump to confirm it was cutting out power and the engine started and ran with no issues. I've order a new CCRM and will see if that fixes the issues... my guess is maybe welding took out the relay in the CCRM....