2014 WK2 Long-crank

[rpaoness]

I have had at least a half-dozen long-cranking evolutions on the WK2, most evident when sitting 6+ hours. It became much more frequent in the last two weeks or so, where more than about 75% of cold starts it would act up. I pulled the fuel manifolds and fuel injectors out of the intake on both sides and inspected for any evidence of a leaky injector. Nothing found, so I resigned myself that it was likely the fuel pump anti-drain-back check valve that was likely causing fuel pressure drop, and considered ordering a fuel pump (Delphi pump is about $200 on RockAuto - requires removal of the cat-back exhaust, driveshaft, and fuel tank to replace). As a last-ditch effort, I bought a bottle of Techron fuel system cleaner, and "B12" cleaner also at Walmart since it was cheap, and ran them both in about 15 gallons of gas left in the tank. Some city driving, some overnight sits, and then a long highway run. So far I'm 100% fixed since putting it in last week - we'll see how long the trend stays. Certainly worth trying another Techron dose since it appears to at least be helping.

[kevm14]

Those are both pretty good products. But not sure it would fix a fuel pump check valve.

[rpaoness]

Cold started this morning fine, but had a long crank after only like 3.5 hours of sitting. Weird

[kevm14]

I feel like you've reached the point where it's time to drive around with a fuel pressure gauge taped to your windshield.

[rpaoness]

I ordered a fuel pressure gauge off Amazon that includes the T/quick connect adapters. Should be in this weekend, but I won't be able to start instrumented runs until the end of next week at the soonest. Started fine today even after >24 hours... I'm inclined to try more B12/techron before I dive any deeper since it's back to more intermittent...

[rpaoness]

Intermittent occurrences got more frequent, so dosed again w/ B12 and Techron. We'll see if frequency drops or stays the same.

[rpaoness]

Hmm... crank position sensor.... ?
https://www.ramforumz.com/threads/hemi- ... mes.57087/

They're only $32...
68140678AB

[kevm14]

That was a Mercedes thing across a few engine generations. FWIW. Never happened to me.

[rpaoness]

It has been super consistent in hard starting - so much so that I've gotten to where I always prime unless it's been sitting less than 5 or 10 minutes. I finally got around to putting the Amazon fuel pressure gauge on it. Kinda of annoying that the stellantis fitting design has long-ish snouts and the Amazon pressure fitting is short so it won't lock on. Used a couple zip-ties to provide axial restraint and it worked fine - double o-ring around the pipe so as long as it stays on axially it seals fine. Looks like it runs 55-60ish psi and drops very rapidly after shutting of the engine/fuel pump. Less than 10 psi in 2-3 minutes usually. One time out of the 3 or 4 starts/stops I looked at so far it did take like 20 min to drop to 8 psi and held at like 6 psi, but looks like that's far too low. Engine doesn't usually start until 20-30+ psi is reached, which makes sense. What I still can't quite figure out is why it will crank for 15-20 seconds when it's at its worst and not fire. High injector pulse width prevents the rail from building pressure, therefore no atomization, therefore no fumes, just dribbling liquid? Weird.

Based on the "gross" nature of rapid pressure loss and no indication of gasoline smell in or near the throttle body or intake manifold I believe leads me to the fuel pump check valve. Probably not worth sending the injectors out for cleaning/testing. Or could have them cleaned/tested just "because" and then only do the pump after they are confirmed good.

[rpaoness]

I wonder if it's worth trying one of these:

https://www.amazon.com/Fuel-Injector-Cl ... 306&sr=8-8