Piston Slap: PATS on the Back for Panther Love?

Sajeev Mehta
by Sajeev Mehta
piston slap pats on the back for panther love

TTAC commentator supremebrougham writes:

Hi Sajeev,

Sitting in my Grandma’s garage is her pristine 1997 Mercury Grand Marquis LS, with a whopping 24,800 miles on the clock. Grandpa bought it right off of Mr. Sesi’s showroom floor not long after he retired.

About two months ago, my Mom and Grandma took the car out for the day to do some shopping. They stopped by my house, and when they went to leave, the car wouldn’t start. I got in and noticed that when I turned the key, the fuel pump was not making any noise.

I pushed the car into my garage where my uncle said he would come and look at it later in the week. A couple of days later, I decided to try it. Sure enough, the car started right up. I took it back to Grandma’s and put it in the garage. A couple of weeks later I went back and started the car — it ran perfectly — so I took it across town and washed it and brought it home, with no problems. Two weeks ago, my uncle and aunt took the car out for the day, and while they were out, the car wouldn’t start, so they had it towed home. A couple of days later, I went out to the garage, and it started right up! We have no idea why it’s doing this. Any suggestions? I want to take the car to the Woodward Dream Cruise to use as my Staff Car for The Brougham Society, so I need it fixed fast!

Sajeev answers:

Pretty easy one for a fanboi like myself, and it has little to do with Panther Love. This thread encapsulates the possible faults. Assuming the car will not crank when twisting the key, I doubt a shredded fuel pump (or frayed wiring) exists on such a low mile vehicle. The fuel pump relay? Maybe, but nah.

The last post on that thread (regarding the PATS key) is the culprit. PATS keys have a transponder in the head, and perhaps yours is damaged in a fall: kinda like smartphones, things happen when falling from a few feet to a solid surface. Check if the PATS warning light in the gauge cluster stays on longer than the normal (2-3 seconds upon startup) or if it flashes. If so, that’s why your Panther ain’t starting.

A new key (either a universal or a factory Mercury branded key) is easy to get at a locksmith, dealership or even eBay. The last link presented also has programming instructions for the new key, so its a cheap and easy fix.

[Image courtesy of Richard Bennett]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.


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  • Supremebrougham Supremebrougham on Aug 13, 2015

    It's a little after 9 PM here, and I just returned home from Grandma's where I have been touching up the wax job and getting it all shined up for the weekend. We took the car to Mr. Sesi's lot last week. It ran perfectly fine till I drove it into the service bay and turned it off. That was it then...They kept the car for almost a week, and tried their best to replicate the symptom, but the darn car would start every time! So they told me to take it home. They said it could likely be the fuel pump, or, where the car had sat for so long (pretty much all winter), there could have been some varnishing of the gas, and maybe my driving it to Ann Arbor, and their driving it and letting it run could have cleaned it out. I drove it home without incident, getting it up to 85 on the freeway. When I got it into the the garage and turned it off, I attempted to restart it, and it started right up! I took it out today for a little ride, and again, no problems. I'm planning on still taking it to the Dream Cruise, where I will be parking it with the Lincoln and Continental Owners Club, as I was invited to do so. A couple of things...1997 was the last year for the regular keys, so no PATS I am afraid... The photo at the top is indeed the car in question! I took that last summer. I'm going to share this with my uncle, as he will be interested in hearing what may be the problem, and try to fix it, as the dealer said it would cost $1100.00 to replace the pump! Thanks everyone for your input, and thanks to Sajeev, I know I can always count on you for a favor :) If you haven't yet, come look up The Brougham Society on Facebook...

    • Scoutdude Scoutdude on Aug 14, 2015

      Wow that is some serious highway robbery charging $1100 to change the fuel pump on a 97 Panther. Yes I understand that they will want to replace the fuel pump "module" and charge probably $500~$600 for it but it is less than an hour job is the fuel is less than 1/4 tank. If it has more fuel in it then that then they will need to siphon some out until it gets low enough to pull the pump w/o gas spilling all over the place.

  • Exfordtech Exfordtech on Aug 13, 2015

    There are two different types of no starts, they require different diagnostic procedures, and this information is critical in trying to diagnose such an intermittent issue. Is this a no crank, no start; or a crank no start? If the latter, observe the check engine light while the vehicle is cranking but not starting. If it remains on during this time, it means that the PCM is not seeing a crank sensor signal, and since it is unaware that the vehicle is cranking, as far as it is concerned, the key is simply in the on position, and it sees no need to fire the plugs, power the injectors or engage the fuel pump. If the light goes off while cranking, the crank sensor and circuitry are good, and you'd need to look at for fuel and or ignition issues. If it is the former, I'd be inclined to check grounds, wiggle test the harnesses and take a good look at the starter circuit.

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