Hello All,
My first post. I have 2003 1500 4wd 5.7 engine
Wouldn't start. I because I work odd hours, i couldn't stay on top of things. But I thought it was the fuel pump. So I replaced it. Ran great for a few days then wouldn't start. I have come to realize that when its raining, or say the morning dew, it won't start or has to crank a bit to start.
The only code found was for bank 1 #1 co2 sensor.


all connections look tight and the vac test passed.


Any ideas what it could be?

 

Did you take care of the codes yet?

 

Extended cranking or lack of firing when moisture levels are high (i.e. high humidity, rain) indicate work spark plug wires. Yes, spark plug wires wear over time and degrade in performance. The moisture content in the air increases the resistance that the ignition system cannot overcome.

Replace the spark plug wires.

 

Correct me if I'm wrong, but the only spark plug wires on a Hemi of that vintage are for the secondary plugs, the main plugs are directly below the coil.

I agree, it is probably an ignition problem, unless you had a specific reason to suspect the fuel pump? Did you test pressures and see they were low? Did you test again after you replaced the pump? I doubt it is the fuel pump though.

You could try replacing the wires, it may help. Inspect the boots for proper sealing and cracks in the insulation along the wire, replace if damaged.

 

I don't have a pressure gauge for testing fuel or injectors.... yet
But there is plug wires on it. As far as I know they are original. I was planning on replacing the Cap, Rotor, wire and plugs with my next check.


btw... When it does crank, it sounds like it starts to kick over but doesn't.

 

You say that the plug wires on it are original. It would help to know how many miles are on the vehicle. But considering they are 11 years old, they are long overdue to be changed.

 

Ya it will have plug wires I didn't mean that it doesn't. I mean the plug under the coil is the one that fires to start the combustion is the one under the coil, which has no plug wire. The one attached to the plug wire only fires when the piston is already on its way down and is just for reducing emissions.

If you haven't done any work to the ignition system in that many miles do a tune up. If it is a hemi there is no cap and rotor. Just change the plugs and wires.

 

I didn't think any of the 5.7L Hemi engines had plug wires... they are coil on plug ignition....

If it's a 5.9L Magnum engine however plug wires & distributor would be a good starting point.....

I'd also change the spark plugs while I was in there too... Remember to use COPPER CORE PLUGS.

 

5.9 l


Got parts ordered at NAPA. I know what I'm doing after work... lol


Thanks Guys!

 

Good to know... b/c you said it was a 5.7L in your original post.. let us know how you make out.