I have a 99 ram 5.2 my battery went dead. and when I first but the battery in it started but had to keep my foot on the gas to keep it running. after about 2 min the truck would idle. know it has a hard time starting. I have no engine light on.

 

After most battery installs you have to relearn the IAC valve, it lets air into the engine at a certain amount for the idle, turn the key on and off about 3 times , start the truck about 3 times ,then take it out for a test drive knowing that you might have to keep your foot on it a little, it will set itself and you will be happy again.

 

it runs good know. I have about 200 miles on it. it is just having a hard time starting. it is worse when the motor is cold

 

the idle relearn issue after a dead/weak battery event is normal for our trucks. they go brain dead for some reason.

the hard starting might be related or might be different. try a few tests.

to test for IAC issue, pretend you have a carb and depress the gas pedal about 1/4 of the way. this bypasses the IAC. if this solves your problem - then your IAC is not acting right.

to retest the IAC and the fuel pump. turn ignition key to on, listen for whine sound. wait a moment. turn off. turn on. wait. turn off. turn to start. this gives the IAC a couple of extra chances to open up. it also gives the fuel pump a couple of extra primes.

report back.

 

ok did both test holding it at 1/4 throttle did not help. but the turning the key on and off helped it so what is my next step

 

What's the battery voltage at with engine off and no surface charge (turn headlights on for a minute to remove charge, then turn off)? A weak battery isnt gonna want to let the truck run when first started.

 

see if you can find a way to test your fuel pressure. there's a test port on the fuel rail drivers side, looks like a tire valve stem/shrader valve thingy. should be 49 psi +/-5.

i doubt that you can rent a fuel pressure gauge, but maybe. check your local parts chain, or maybe get a shop to do it. it only takes 5 minutes. a fuel pump is expensive, so you want to sure before you go down that road.

with the gauge you can test it with ignition on but not running, then again while running to see if it'll hold steady, and then one last time about 10 minutes after you shut it off to see if its holding pressure.

a shade tree method is to turn the key on one time, then off, then press the valve. if the stream of gas hits you directly in the eyeball at high speed, that's about 49 psi. don't smoke....

 

any chain auto parts stores that have a loan a tool "program" (autozone, oriellys, advance auto, etc.) will lend you a fuel pressure gauge kit for ~$100. Bring the kit and receipt back and you get your refund.

 

By turning your key off and on, your priming your fuel pump so sounds like your losing your prime in the fuel pump. to be sure you need to have a fuel pressure test done on it.

 

Ok I got a fuel pressure gauge will do a test