2002 fuel pump only works w/ charged battery

[edward301]

Have been having issues with my high mileage 2002 T Bird not wanting to start unless I start it every few days.

Today I decided to figure out what the problem was. Had voltage so figured it was the pump motor itself. The
battery is four years old, so giving it a good charge to see where the standing voltage is.

I put the charger on at 30 amp charging rate, gave it ten minutes to charge up, and car immediately started.
What I figure is pump motor is slowing getting weak due to age, and unless your battery is well charged with
good voltage the pump motor does not have the starting torque needed to get the pump turning. Did not
blow fuses, simply would not start pumping without enough voltage.

Will see what my battery standing voltage tomorrow. I now agree with others these T Birds are sensitive to
the correct voltage.

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[74 Harley]

You may also want to check the fuel pump relay, it may not be clicking on like it's supposed to.

 

[edward301]

I actually changed the relay about a month hoping that was the issue, made no difference.

 

[vicsrc]

Ford recommends A special battery for the Tbirds
I tried 2 different brands of battery and it was not until I put in the recommended battery did it work

Ford Motorcraft® Battery | Battery Offer | Ford Service Specials​

https://www.fordservicespecials.com
https://forums.fordthunderbirdforum.com/javascript:void(0)
Motorcraft® Battery: Only $109.95 With A 2-Year Warranty At Your Ford Dealer. Or Redeem 22K FordPass™ Rewards Points. Members Earn 10 Points Per $1 Spent On Service.

I know it sounds stupid but this is what worked for me

 

[Cmmclain]

I am a "snowbird" and park my 2004 PCR for five months. I disconnect the battery as the last step after filling the tank with fresh Premium gas. I had to replace the battery last year because it would not fully charge with the small charger. It had an original 650cca Motorcraft battery several years old (I have owned the PCR for 6 years).

The Ford dealer put in the "New Version" battery which is 750cca !!!. (and they forgot to connect the vent tube) My battery charger could NEVER fully charge the new battery after two days. I took a planned 400 mile weekend trip and, put the charger on when I got home. The charger read full, and has kept it up since then.

My theory is the the internal drain on the battery is greater than the "intelligent" battery charger. Therefore, these heavy duty batteries are draining faster than our chargers can keep up with. Also, I believe that many of the control module failures MAY be caused by the draining of the battery for too long. (As an electronic engineer for 40 years, you never know what the cpu will do when it hits "marginal" voltage, it can go crazy.) Bad or loose connections can read 12volts+, but when a current draw, like starting, the voltage drops quickly. Clean tight connections are mandatory for top performance.

IMHO, My recommendation is to NOT keep the security alarm enabled while sitting for a long periods (drains the battery faster when enabled). Drive occasionally for extended (1-2 hours) periods to fully recharge the battery. (Short trips never fully charge older batteries.) When storing for winter, disconnect the battery AFTER fully charged. Use the manual key to lock the drivers door, leaving a small air gap with the window down slightly (1/4 inch). Cover the baby for winter. In spring, use the manual key to open the trunk manually (lock located behind the driver's seat) and recharge the battery BEFORE reconnecting it.
Thanks.

 

[biddle]

after filling the tank with fresh Premium gas.

I would fill mine with non-ethanol gas for storage if possible. That's always the best-case scenario and Stabil with Ethanol Fuel is 2nd best. Find stations- https://www.pure-gas.org/

 

[1984shovelhead]

Assuming the battery was well topped off when parked my experience is that even a battery tender jr.which I think maxes out at 750 ma.will keep a healthy battery topped off in my climate of southwest Virginia car stored inside alarm left off .although I have no proof I agree marginal voltage can do no good for these cars.

 

[edward301]

Update, while a charged battery did help the fuel pump it finally gave out. I decided to go ahead and replace it, forgot what a
pain it is to replace one. Tight working space, and difficult to get the large spinning nut back on while holding the fuel pump assembly
in place. I was amazed to find out the fuel pump was original. See photo manufacturing date of 2002.

And the battery while four years old is doing fine, holding voltage well. And the car has 129,965 miles and works great.