Got my first check engine light 6 months ago, P0456 (evap emission system leak detected very small leak). I had a smoke test, found a clamp that was broken, replaced the clamp, replaced my fuel cap and cleared the code. Code Came back after 62 miles. Had a smoke test again, they found no leak at all. Repair shop told me my fuel pressure is low and that the root cause of the issue is my fuel pump and I should replace it.

So now I am trying to verify the fuel pressure is bad. Rented a kit to check pressure from O'Riley, I get wobble from 54-58 when idling, I get a solid 56 PSI when I push the throttle a little or a lot, and when I kill the engine it went to 53 and stayed there for atleast an hour.

So IDLE : wobble 54-58
Throttle: 56
Off : 53

The specs that I find are 58 off and 60 idle.

Is the shop right? Is this pressure a sign that the fuel pump is causing my EVAP code?

Also, I have no difficulty starting my engine, no noticed loss of power, no lag when I accelerate, so it does not FEEL like my fuel pump is failing.

2004 Ram 2500 4x4 with 5.7 Hemi 110k miles.

 

Evap codes have nothing to do with fuel or fuel pressures. IMO if the truck is running good, not stumbling or lacking power leave it. Clear the code, see if it comes back again. It's possible it didn't get cleared the first time.

 

I had no MIL for a week, then it came back. That was after the shop cleared it. I'll do the battery method tonight and see what happens in a week.

Is there post of the system that could throw the code but not leak during a smoke test? Like the purge solenoid opening during the self test when it's not supposed to?

I may just buy some of the cheaper evap components and replace them just to see if it works

 

You would get a specific code for other issues with the system. Is it the same code?

 

The small eval leak code is the only one I have had the whole time. I had a intake air temp sensor failure code, bought a new sensor code went away.

No other evap related codes.

Are there other codes that would show if it was something outside gas cap/line leak? Because I got a smoke test with no leaks but still have the code. It was NTB who did the test. Should I trust them? I didn't see the s test in person.

 

Replaced the Evap pressure check value next to the EVAP Canister and removed all the hoses I could reach and inspected them. Then put them all back with new zip ties. No change, code came back after 70 miles.

Anyone know if anything related tot he fuel pump that would cause this code?

My next step is the test the purge value.

 

Finally got a better explanation to why the fuel pump should be replaced.
The shop claims that the seal around the fuel pump in the top of the fuel tank is leaking. That most likely the ring that holds it in place is rusted and punctured the o-ring seal. They could not see it without dropping the tank.
This makes more sense. What do you guys think? Should I believe them and go forward with dropping the tank and replacing the seal?

NTB quoted me 600 for a new pump.
A small shop down the road quoted 530, or offered to only replace the fuel pump seal (and leave the pump) for 250. Whats the recommendation here?

 

NO>>>>>>the fuel pump is not the cause of the evap code UNLESS the top of the pump is not sealed. If the pump ring is a metal one, YES I've seen them rust right through. The mating piece for that ring is also metal and it is part of the tank. You might be looking at a tank AND pump replacement.


Here is one from a 2004 Durango I did a couple months ago. It took 2 tries to find the leak, because the smoke wouldn't come out the first time and it passed the test. It was rainy that day and I think the moisture sealed the hole with the wet muck. Don't let them put an AirTex pump in it.

 

TNtech - WOooo that is one nasty pump. Hopefully mine does not look like that. Overall the truck is very clean and the part of the tank that I can see is good. Maybe Ill try to sneak my phone up there and take a picture of the tank.

So your recommendation would be to LEAVE the pump and only replace the SEAL and maybe RING. Then hope that the tank itself is in good condition.

And yes, when I told the shop they I wanted a high quality pump they said that they never use AirTex. Usually Precision or Bosch.

 

Good shop Yeah, but I hardly ever see the rubber ring go bad.