Hey all, I have a 2001 dodge ram 1500 5.2 4x4 that I’ve got running a lot better, put some new parts on it and it ran a whole let better, drove for about 30 miles then a cel popped up with code p0172

I have since tested fuel pressure and it seems ok, it doesn’t hold pressure constant but will stay above 30psi for about 30-45min, I’m wondering if the slow leak is because of an injector

So I’m wondering if anyone has had a similar problem or advice before I just start loading up the parts cannon, any help is appreciated

Throttle is a bit laggy at idle too

Parts replaced:
Spark plugs and wires, cap and rotor, coil, water pump, thermostat and housing, coolant temp sensor, timing cover, timing chain, harmonic balancer, valve cover gasket, and front seal

 

What plugs did you install?

Pressure leakdown *might* be a leaky injector, or it might be a failing check valve. You should be seeing 49 PSI at key on, or engine running, do you get that??

How many miles on the truck? Original O2 sensors? Federal or California emissions?

 

I put Ngk 7100, I believe they’re platinum plugs

I get 45psi with key on,drops to about 42 within 3 minutes with key off, stays at 50 while running, doesn’t move when I hit the throttle, the gauge kinda bounces a little which I think is normal

150,000 miles, I believe the o2 sensor are the original, I believe federal emissions but I’m not 100% sure

 

These engines really don't like the rare earth plugs, standard copper is best.

Fuel pressure is good, so, not a pump problem.

Might not hurt to replace the O2 sensors. NTK or Denso sensors only please. These trucks don't play nice with Bosch sensors either.

 

Ok thanks I’ll have to order those, thanks for your help, if I remember I’ll update