99 MERC SABLE - intermittent start problem
 

My dealer still has the car and is trying to duplicate and diagnose this
intermittent problem. Perhaps someone else has wisdom that can help.

AUTO: 1999 Mercury Sable LS sedan, 24V, 58,000 miles.

ISSUE: Cranks and often ignites but idles at low (<500) RPM until engine
dies.

OBSERVED SITUATIONS:
- Drive car ~20 minutes or more on hwy and city.
- Stop car for 5-10 minutes. Quick in/out of a store.
- Return to car and try to start.
- Car cranks fine, and engine may chug at low RPM, ~350. (The *sound* is
similar to a flooded engine struggling to run.)
- Repeat start routine, same condition.
- Let car sit for 30-45 minutes and it starts and runs fine.
- Three events like this in the last 45 days.

SUPPORTING INFO:
- Main key ring has SpeedPass RFID stick, but condition occurs with and
without this set of keys.
- Heat vs Fuel Pumps is known issue. I try to keep >1/4 tank of gas in
summer.
- When the car starts, it runs perfectly - smooth and powerful.
- Dealer replaced Fuel Pump Relay after event #2; then event 3 occurred.
- After events 2 and 3, no apparent error codes when connected to
computer.
- There was once a PATS system error discovered in the log.
- I did not think to observe the THEFT indicator during these events.
- After complaining of musty smell in climate control, dealer installed
"feature" that runs the climate control fan to help clear out the air
chambers.
- There have been four total events like this within 3 years. First
event at 38,000 miles. No start, no fuel pump sound. Sit for 1 hour
waiting for tow. Started right up - could have driven it onto the
flatbed. Replaced fuel pump (not sure why).

QUESTIONS:
- Has anyone observed (and solved) this issue?
- Do fuel pumps behave intermittently or do they fail "hard" and not
recover?
- Any clue why time is my friend with this error? That is, what would
change by letting the car sit for 30-45 minutes?

Thanks in advance!
NZ

Posted to: alt.autos.ford and rec.autos.tech