Hot start problem resolved due to failed check valve in the DMCH fuel pump

[kings1527]

Sorry to hear about the leak, Jon, but wow...great job troubleshooting this. If it's in Dave's hands now, we all know it's in good hands!

[DeLorean03]

Wow, that was a thorough investigation. Good job on tracking this one down!

[jawn101]

Can't take all the credit, Dave is the man when it comes to this stuff. I just hope he can find and fix whatever the issue is, because I swear there is *nothing* visibly wrong with that pump. I have no idea what's leaking!

Edit: I should say that I'm glad I took the time to dig into what was really just a minor annoyance. It's a good lesson to investigate any and all abnormal behavior in your car - you never know when a minor symptom could be hiding a major problem!

[Ryan S.]

Good job diagnosing the issue. Let us know what Dave finds out.
Mine worked really great after the external check valve. But recently, I have been experiencing some mild random cold start issues. Cannot figure out the cause. It stars fine in the "cold" mornings but when I start in the afternoon or after work, I have to crank it for several seconds. But not always. Some afternoon, it starts fine.

[NightFlyer]

Glad that you were able to get this mystery solved!

Hopefully it's a fluke as opposed to being an endemic problem...

[jawn101]

Glad that you were able to get this mystery solved!

Hopefully it's a fluke as opposed to being an endemic problem...

Thank you. Your advice and responses have been invaluable in tracing the issue as well. I also hope that it's a fluke and not endemic, but realistically how would anyone know without checking? I put the bad unit in the mail to Dave today and can't wait for the triage and AAR on it, and to get the car running again!

[NightFlyer]

Only way to know other than checking would be to run the tank low and see if they experienced the bucking / fuel starvation issues that you did.

I've run my unit for roughly 4 months and about 5,000 miles. Before putting the car away for winter hibernation, I ran the tank down to practically fumes (less than a gallon remaining) before adding a can of seafoam and 5 gallons of ethanol free fuel and driving home, and didn't experience any bucking / fuel starvation problems - knock on wood. I was actually sweating whether I'd make it to the gas station with the e-free fuel before I completely ran out of fuel and would end up having to walk.

So, I presume that thus far, other than having a faulty internal check valve, my unit is operating properly.

[David T]

Didn't know you had the newer unit. They do seem to have as many problems as they are supposed to solve! Between leaks, bad check valves, and the level indicator not being accurate, it would seem you are trading one set of problems for another set! Too bad, it could have been done much better. While it is removed you might as well clean the tank out.The good news is you finally have your hands on the problem.

[jawn101]

Didn't know you had the newer unit. They do seem to have as many problems as they are supposed to solve! Between leaks, bad check valves, and the level indicator not being accurate, it would seem you are trading one set of problems for another set! Too bad, it could have been done much better. While it is removed you might as well clean the tank out.The good news is you finally have your hands on the problem.

The unit does seem to have some teething problems but I don't think I can agree that it's as bad as the original setup.

The tank was sanitized prior to installation of the unit (as required by DMCH for warranty purposes) but you're right - I plan to give it another wipedown while the hole is open all the same. The hope is that nothing was missed the first time but who knows.

[kings1527]

I agree that this setup seems to be a big improvement over the original. I haven't had any issues with my fuel sender not reading correctly on the new unit. And DMCH is now selling the new setup with a brass external check valve (with a price tag now of $419 instead of the original $399). Of all the units that have been sold thus far, this is the only one that I've heard of having this type of a leak.