2001 Explorer Starting problems

[sirplayalot]

Hey all, my dad has a 2001 Ford Explorer with about 246,000 miles on it. Trans was replaced at about 170k miles. The truck has been runing fine until recently. When you first start the car, after it being off for a day or so, it will start, RPM will drop, and it will stall/shut off. The only way to stop the RPM's from dropping and keeping the car on is to press the gas when it gets below the 500rpm range. After the truck is on for about a minute or so, it works fine, no matter how far he drives! It even took him on a trip out of state. The issues only happen when the car is first started after being off for a while. Any ideas as to what can be causing that?

Thanks!

 

[brblx]

well, i would say it's one of two concerns. choice a) there is something wrong with the idle circuit that is causing it to not fast idle properly when cold. choice b) there is another issue that is causing it to run poorly that is specifically related to sitting for a day or more. most likely would be a loss of residual fuel pressure, which causes excessive crank time and/or stumbling upon initial startup. typical cause is a torn diaphragm inside the fuel pressure regulator (4.0L iirc have a vacuum operated regulator on the fuel rail if that's his engine). pull the vac line off it and see if gas pours out (or even if you get a strong gas smell).

does it smoke at all when it starts after sitting?

 

[LTC8K6]

Sounds like the IAC valve.

 

[sirplayalot]

does it smoke at all when it starts after sitting?

No, it does not smoke.

I am going to see what I can do about the IAC valve.

 

[brblx]

should take 30 seconds to check for fuel on the back side of the regulator.

assuming you don't have a fuel pressure gauge, another way to test it would be to slowly cycle the key a good 6-7 times after the car's been sitting. each time you click the key on, the fuel pump will run briefly. if all the pressure is gone out of the line, it will take a good few 'primes' of the fuel pump to get the car the start smoothly. if this makes the car start smoother, you know it's a fuel pressure issue.

IAC is harder to test for. if it's cheap, you could just replace it and clean the throttle body and see what happens (should still help general driveability if nothing else).

 

[5150MyU]

Alot of cars require that the key be off for 10 seconds or so before the fuel pump will power up again.
So you can't just cycle the key without waiting.
That means turning the key to the run position causes a 3 second prime (roughly)-when cranking the fuel pump always runs-once the computer sees that the engine is running the pump always runs.

 

[LTC8K6]

Sometimes, giving the IAC a whack or two will get it to work again for a little while.

 

[Pacfanweb]

Sometimes, giving the IAC a whack or two will get it to work again for a little while.

This is the most likely culprit.

 

[thegimp03]

Hey all, my dad has a 2001 Ford Explorer with about 246,000 miles on it. Trans was replaced at about 170k miles. The truck has been runing fine until recently. When you first start the car, after it being off for a day or so, it will start, RPM will drop, and it will stall/shut off. The only way to stop the RPM's from dropping and keeping the car on is to press the gas when it gets below the 500rpm range. After the truck is on for about a minute or so, it works fine, no matter how far he drives! It even took him on a trip out of state. The issues only happen when the car is first started after being off for a while. Any ideas as to what can be causing that?

Thanks!

Did your dad ever figure out the issue? My 2001 Explorer now has about 124,000 miles on it and lately it's been having the same issue. I initially thought it was the battery, and since I couldn't remember the last time the battery was replaced, I bought and put a new one in last weekend. Seems like it will start OK in the morning, but it'll have problems in the evening, and I'll have to shut it off for 10 seconds or so before trying again.