trouble starting/ wont stay running

[crazyi]

i am currently helping a friend try and fix his 1999 explorer sport 4.0l. every once in a while it wont start( turns over but wont fire) if he holds the gas pedal to the floor it will start. also the other day on the way home he had to ride the brake and gas to keep it running. if he tried to hold the brake and let it idle at a light it would die. anybody know where he can get a fuel pressure gauge that fits on the shrader valve that comes off the fuel rail on the drivers side? we pulled the codes with a odb 2 scanner twice and it didn't pull any codes. i'm thinking maybe a fuel pressure sensor or maybe a cps. but with it not wanting to idle do these things have an idle air control valve like 5.0 mustangs ( all i really mess with.) any help is really appriciated. sorry for the long post.

 

[udmsvt]

i am far away from expert, but previous experiences say probably is the fuel pump, but hopefully its just another aspect of the fuel drliv. system.

 

[mrboyle]

Yes they have an Idle Air Control motor. From your description I'd say that the problem is due to a sticking IAC.

 

[TPLYNCH]

Hard start may be a problem with the check valve in the fuel pump. Have your friend cycle the ignition to ON and OFF 2 or 3 times before turning all the way to start to allow the FP to prime/pressurize the lines. I second the IAC for the stalling problem. Try cleaning it first. It's very simple. Search for IAC for lots of threads about it....

 

[dogfriend]

I vote with mrboyle. It sounds like the IAC is sticking closed.