DMTL pump or leaking fuel filter (dust cover)

[Michael Gain]

After checking my transmission fluid level and shutting off the vehicle, I thought I would finally check out whatever has been running under the rear of the truck.

Using my poor man's automotive stethoscope (long pry bar to my ear), I found that the DMTL pump is continuing to run for about 2-3 minutes after shut down.

From what I understand, the pump pressurizes the tank to check for leaks in the fuel system. If any are found, a code is recorded--no codes in my case.

So, using that logic, would one assume that the DMTL pump is bad and not building enough pressure? Or, should I assume that there is a leak in the fuel system, forcing the DMTL to run longer to build pressure?

I looked in this thread:

https://www.landroverworld.org/thre...-no-error-codes-no-visible-leaks.29229/page-6

And lots of google; but I cannot find anything definitive.

Thank you all in advance!

 

[jlglr4]

I’m not sure there is anything wrong with it. I posted a while back about a pump running after shut down as well. Then, a few day later, noticed the same thing on my wife’s volvo. I just didn’t think the LR had an electric emissions detection pump, but apparently it does.

Started doing some looking into it and came across an article that mentioned LR using a key-off type EVAP leak detection system. Basically, if the there are a bunch of conditions met (driven for a certain amount of time, some level of fuel, etc. - can’t remember the details), the car will turn that pump on after the ignition is shut down to pressurize the tank and test for evap leaks. Of course, I didn’t book mark the page and couldn’t find it afterwards. Been meaning to look into again, just haven’t gotten around to it.

In any case, my car does the same thing, and my wife’s volvo does it too. Sometimes (but not every time) when I shut it down, the pump will run. Wife’s car starts the pump several hours after shut down.

 

[Michael Gain]

I think I may have posted to your thread suggesting the fuel pump (as that was the majority of Google articles), but it is definitely the DMTL pump.

I wouldn't be as worried with it if it were not a new symptom. It just started after my whole misfire fiasco, and the DMTL did not run on my wife's LR4 when we still had it.

I'll try to call an Indy that I sometimes use to see what their thoughts are as well. Hopefully, we can figure this out together!

 

[jlglr4]

Yes - I remember your comments because I recall you saying you had a similar sound going on. I’m suspicious of the pump running for the same reason as you - I don’t remember hearing it before, then one day it started doing this and I hear it more often now.

I’m also seeing some slightly high fuel trims - not enough to throw any codes or create any drivability issues (runs great actually), but I’m now wondering if there might be an evap system leak that’s letting unmetered air into the system - maybe also causing the DMTL to run more. Maybe the purge valve? I’d expect a code though.

I also recall someone else posting a while back with a leak at the evap leak detection pump. Discovered with a smoke test. So, maybe that’s a possibility?

 

[Michael Gain]

I also have elevated fuel trims (+7% if I remember right) and some idle bogging when coming to a stop.

The purge valve will definitely throw a code -- I forgot to plug the connector back in after supercharger reinstall. The truck was quick to tell me I messed up.

I have a smoke tester. If I get some time this weekend, I'll try to run some smoke through the line.

I did not get a chance to call the Indy, but just assume there is something that needs fixing.

 

[jlglr4]

It’s got to be more than a coincidence that we both have these same two symptoms. I tried making a quick and dirty “pickle-jar” smoke tester a while back using just things around the house, but it kept melting down on me. Let me know what you find. I’ll do the same.