Hi all;

I have a 1997 Dodge Ram 1500 (V8 5.2L; 168,000 miles) which has been giving me trouble as of late. Some days it will start up just fine, but others it will not. It does turn over regardless, but sometimes it simply will not catch and hold. If I give it some gas, it will stay running until I let off.

Here is a list of what I have done/checked:
-Replaced Spark Plugs, Distributor Cap, and Rotor
-Cleaned battery posts and secured connections
-Cleaned throttle body
-Cleaned idle air intake
-Replaced leaking vacuum hose
-Fuel regulator sensor (checks out as okay)
-Fuel pressure (reading was in the middle of the OK range)
-Changed relays
-Added two bottles of fuel injector cleaner

When the key is turned to the on position, the fuel pump kicks right up and apparently has no issue. The engine definitely has spark; a quick-connect check setup I used on the engine coil had a spark plug firing without any trouble. The problem seems to be fuel related, but I can find no leaking lines, the fuel pressure is okay leading me to believe that the pump is okay, and there is a double dose of fuel injector cleaner that does not appear to be offering any help.

Any advice, comments, or tips are greatly appreciated; thanks for your help.

 

so - whenever it doesn't want to start, you can MAKE it start by pressing and holding the gas pedal?

if so, i'd replace IAC (idle air control) and TPS (throttle position sensor).

any CEL codes ?
the other 2 important sensors are crank position and cam position, but those are more timing related, and not bypassed as easily as mashing the gas.

 

Another issue , could be the crank sensor . It could be the sensor , or the CPS wiring to the PCM . Rare , but the wires can p/u signals from other wires and cause intermediate issues . Fix is to shroud the wires separately .

What was the fuel pressure reading BTW ? Did you do a flow test as well ?

 

Very good question and you are not the only one with this issue. Mine is the same way sometimes it will start other times it won't. If it won't start and I hold down the gas mine will start up.

Does your when running ever stall when you let off the gas to come to a stop?

Is there a way to determine if the IAC,TPS,Crank postions sensors are bad? I only ask is becaust to replace those sensors is about $200 bucks.

I am getting a check engine light but since the truck won't drive without stalling hard to get it to autozone to get it tested. I know I am adding more to the problem but maybe OP is having some of the same issues.

 

hey quack, on your 2001 you can read your own codes by doing the on-off-on-off-on with the ignition key.

i don't think there's any way to test the IAC or TPS other than to invest in a spare set of new, known, good ones and swap them in. some people talking about cleaning them, but i've had zero luck in doing that. you can get them at autozone, advance, or napa for about $50 each instead of the $80 at the stealer.

 

Is there a DIY on this on-off thing?

Yeah the Crankshaft Sensor is $70 @ autozone, the IAC is $33 and TPS is $55. I haven't priced the camshaft one yet. I figure new engine it can't hurt to replace with new stuff. I just really don't like throwing money at a project unless I "know" it will make an improvment.

Figure out how to run those codes as well and go from there. Will probably clean the TB again and replace those 3 sensors while I am waiting next week on my PCM to come back.

 

just turn the ignition key forward to where all the lights come on, but not the starter,
thats your first ON,
then back one click OFF, forward one to ON, back one to OFF, forward one to ON and then watch your digital odometer. it'll display any codes one at a time, and finish with "done". pause about 1 second at each on/off.

if you replace sensors, replace them one at a time and reset the pcm each time. if it doesn't fix the problem keep the old senor as a good one, and you can swap it in the next time things go whacky.

 

You could also check the fuel pressure if it is not a sensor.

 

Most likely dirty or bad IAC..lots of threads on this same issue..I have the same problem myself once in a while. The weird thing is it seems to be more frequent in the colder weather for me?. After running it with your foot on the gass for a couple mins its fine... Could be coincidence.

 

Thanks to all for the input.

It appears that the IAC is being mentioned frequently, so I will go back and give more specific attention to this unit.

I also seem to have more trouble when it's cold. Much like you, after giving the vehicle gas for a little bit, the engine will eventually stay running. I'm going to do some price checking on IAC parts around here and I'll try and post if anything resolves the issue so that others who encounter the same problem may save some time.

Thanks again to all.