Leaky Injector or Bad Fuel Pump

01 Taurus Vulcan 41000 miles

About 6 weeks ago, I started noticing a starting problem - when I go to start the car, it requires a long crank time or 5 primes. Once I do that, it starts up and runs fine.

If I turn the car off, let it sit for 10 minutes I just have to turn the key to start for no time at all and the car starts right up. The car used to require atleast 1 second of cranking whether it say for 1 minute, 10 minutes, 2 hours, 2 days of 2 months (been there done that).

Could it be a leaky injector is leaking fuel into a cylinder and letting it start quicker when it's off for a few minutes but letting all the fuel out when it sits for a while?

If it were a fuel pump with a bad backflow valve or whatever, would that cause it to start quicker then it used to?

I'd lean towards the bad fuel pump (or restricted fuel filter) based off your second sentence. And since you mention that if it sits for 10 minutes, it starts easily would indicate to me that the fuel pressure regulator is at least not stuck open.

You should either buy or rent a fuel pressure guage and check the fuel pressure at a cold start. While you're at the parts store, pick up a bottle of fuel injector cleaner and add it to the fuel tank.

If it's a leaky injector, you may notice a smell of raw gasoline in the oil as at least some of the fuel will eventually leak past the rings and into the crankcase.

-Rod

If it sits for 10 minutes, it is overly easy to start.

It shouldn't be clogged fuel filter, I replaced it about a year ago.

Calculating my gas mileage since August, I noticed that the same time this started my gas mileage went from ~30 to 24

Well, it may be worth your time to check the coolant temperature sensor to make sure it is reading accurately (with either a scan tool or multimeter) and the Mass Air Flow (MAF) sensor elements for contamination. The Coolant Temp Sensor could contribute to both the starting concerns as well as the fuel economy. A contaminated MAF would most likely effect the fuel economy, but would not explain why cycling the ignition on a cold start helps get the engine started.

-Rod

I'll see if the MAF is clean, I'm assuming that can be visually checked? How would I check with a multimeter?

The MAF would have to be removed from the housing to check/clean it. This usually requires a security Torx bit, T-15 I believe.

The Coolant Temp Sensor (CTS) can be checked using a multimeter on the resistance/ohm scale. Place it across the CTS and the resistance should vary depending on coolant temperature. I'll have to see if I have the table showing approximate resistance for a given temperature.

-Rod

When mine acted up I used a can of Sea Foam injector cleaner from Advance Auto and whatever was wrong it fixed it. http://www.seafoamsales.com/motorTuneUp.htm

I've done a few fuel injector cleaners ... no result with them.

I'll check the resistance of the CTS when I get home this weekend.

If the MAF were dirty, wouldn't the car idle bad?

Also, how would I check for a leaky injector?

When my MAF in my 1993 SHO was dirty, I had no driveability issues whatsoever. My fuel economy dropped from 17mpg to 13mpg though a few weeks after I cleaned and oiled my K&N filter. I pulled the MAF and noticed the elements were dark grey. I cleaned the elements gently with chamois swabs and electrical parts cleaner, cleaned the K&N and applied less oil, put it all back together and the fuel economy was back to normal.

Well, to check for a leaky injector, you could monitor the fuel pressure and see if it is in spec, as well as check for how quickly the pressure bleeds off with the key off. If it bleeds rather quickly, then wait about 5 minutes and pull the spark plugs one at a time. Inspect them for wetness due to fuel. If you find one or two that are wet with fuel, suspect the injectors on those cylinders.

-Rod

I went to clean my MAF last month and was surprised the torx was a security style. Why in the world did they do that? Did a Ford designer take some money under the table from a security torx bit salesman? Normal torx bits should be more than enough deterent if they felt it was something that shouldn't be messed with by the unknowing.

"went to clean my MAF last month and was surprised the torx was a security style. Why in the world did they do that?"
Have them on my 03 and cleaned it and said something about them and the only thing I can come up with is they cost $125.00 so maybe they're trying to prevent petty theft. 'Course, . . . any *good* thief, (oxymoron), "in the know," would bring the right tools with him anyway.

I didn't have the torq driver so I took the hose clamps off, unhooked the MAF and sprayed the MAF wires with electric parts cleaner, let it dry then hit again for good measure and I guess it worked. I don't drive very fast 'cause I'm 65 but I have a heavy accelerating foot and all I get is 21 around town and never had it on a long road trip over 60 miles, so don't know what it would get on the highway.

I believe they don't want people playing with the MAF. I'll try pulling one spark plug at a time though this weekend.

"I believe they don't want people playing with the MAF."
'Prolly correct and I read somewhere the sensor wires are very fragile and not for touchy-feeley.

As far as the security torx, I'm thinking about just getting the dremel and turning it into a flathead screw.

As far as the security torx, I'm thinking about just getting the dremel and turning it into a flathead screw.

You could do that, but the security Torx bits are not that difficult to find. Many auto parts stores carry them, some farm equipment supply stores have them, and some good electronic parts stores carry them as well (ie: you probably won't find them at Radio Shack).

-Rod