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

[DMCMW Dave]

. You can have some of our perpetual spring if we can have some of your water....

Heh - our "water" is piled up 6 feet deep at the end of the parking lot now. Too dark for photos tonight.

[Tillsy]

Here you can see the hose cut out of the car and the extent of the kink. Everyone who is reading this post should please take this warning quite seriously - the OEM fuel lines on your car are *NOT* suitable for active use anymore! If you haven't replaced them all you are just asking for trouble.

Absolutely agreed - one part of my initial restoration before starting her the first time was replacing every fuel hose, and sure enough a number of them had splits and deformations. Only two I hadn't done were the FV lines as unfortunately it's not well known that most vendors have new stainless braided ones, so I waited on a specific particularly slow vendor. Now done and sleep much better knowing the last are replaced.

Fantastic to know the new pump was not at fault.

[NightFlyer]

WOW - What a completely unexpected end to that mystery. Glad it was finally solved and that the fix was cheap

With that said, the kinked hose that you removed looks different than the stock/OEM hose that was used at the accumulator, thus I'm wondering if that hose wasn't in fact a prior replacement somewhere along the line.

Anyway, thanks for following up and keeping us in the loop!

[jawn101]

WOW - What a completely unexpected end to that mystery. Glad it was finally solved and that the fix was cheap

With that said, the kinked hose that you removed looks different than the stock/OEM hose that was used at the accumulator, thus I'm wondering if that hose wasn't in fact a prior replacement somewhere along the line.

Anyway, thanks for following up and keeping us in the loop!

You're right, I have documentation that the line was replaced in 2010 (before I got the car) along with the accumulator. Just hard for me (and Dave) to believe anyone would use this inferior style hose that late in the game. But hey, anything is possible right?

[Bitsyncmaster]

I thought it funny that "OEM" hose still had the black cover on it. I never replaced my hose at the accumulator and that black cover completely fell off in pieces. I was getting worried I would need to do the hoses until I saw your last post that it was not OEM.

Nice to know the new pump has an overpressure relieve. Maybe that is the culprit rest pressure problem which is solved by an external check valve.

[jawn101]

I thought it funny that "OEM" hose still had the black cover on it. I never replaced my hose at the accumulator and that black cover completely fell off in pieces. I was getting worried I would need to do the hoses until I saw your last post that it was not OEM.

Nice to know the new pump has an overpressure relieve. Maybe that is the culprit rest pressure problem which is solved by an external check valve.

That kinked hose may not have been stock to the car, but it was definitely in the OEM style - rubber outer, braided intermediate layer and a plastic core. I think the problem I saw could definitely happen to the OEM ones as well, since I believe the plastic core to be the problem - it held the kink.

I wonder if you're right about that relief valve being partially to blame for the rest pressure issue. If true, I'm still glad it's there and think it was a very logical step for DMCH to add the inline check valve as part of the kit. That way you get the benefits of both for all of 5 minutes extra work.

Since it's still early here and the roads are unpopulated, I just hit a big, wide and empty 70MPH highway near my house for 20 miles or so of spirited cruising. There is a noticeable improvement in throttle response and acceleration at highway speeds now. I also noticed a much reduced if not totally eliminated effect of "bogging down" when running in a slightly higher gear at a lower speed. Example - I like to take the turn into my neighborhood in 2nd, and if I slowed down a little too much before turning in, I'd have some chugging while the motor caught back up. Don't have that now.

[NightFlyer]

The stock/OEM hoses are technically a nylon core. And although similar in appearance and design to the aftermarket kinked hose that you removed, they're also very different in terms of thickness of each layer - for example, the stock/OEM hoses have an extremely thin outer composite covering that frequently flakes off the braided fabric mid-layer, whereas the hose in your picture appears to have quite a thick layer of rubber composing the outer cover. Also interesting how the aftermarket hose in your picture doesn't appear to contain any markings on the outer cover, which IMHO screams cheap generic. While it's probably a good idea to change out the original hoses from the accumulator if one is still running them, I wouldn't necessarily call it an absolute necessity.

[jawn101]

The stock/OEM hoses are technically a nylon core. And although similar in appearance and design to the aftermarket kinked hose that you removed, they're also very different in terms of thickness of each layer - for example, the stock/OEM hoses have an extremely thin outer composite covering that frequently flakes off the braided fabric mid-layer, whereas the hose in your picture appears to have quite a thick layer of rubber composing the outer cover. Also interesting how the aftermarket hose in your picture doesn't appear to contain any markings on the outer cover, which IMHO screams cheap generic. While it's probably a good idea to change out the original hoses from the accumulator if one is still running them, I wouldn't necessarily call it an absolute necessity.

Fair enough. Though this hose did have printing on the other side and was originally sold to the PO by DMCCA.

[DMC5180]

One more thing about the OEM hose. Yes the OUTER sheathing cracks and falls off, but that does not mean the inner NYLON core is compromised (CRACKED,KINKED or LEAKING) It just looks BAD. I would like to know who the Original manufacture of that hose is and if they ever did any kind of long term testing.

I think it has been proven that NYLON core is better than TEFLON. Now I'm wondering what the the inner core is of the SS braided fuel lines is.

[NightFlyer]

One more thing about the OEM hose. Yes the OUTER sheathing cracks and falls off, but that does not mean the inner NYLON core is compromised (CRACKED,KINKED or LEAKING) It just looks BAD. I would like to know who the Original manufacture of that hose is and if they ever did any kind of long term testing.

I think it has been proven that NYLON core is better than TEFLON. Now I'm wondering what the the inner core is of the SS braided fuel lines is.

I concur about nylon being preferred to teflon. Most OEMs use nylon cored hoses.

I actually started a thread over on Today discussing the true value of the braided ss fuel lines that the various vendors offer:

http://www.dmctoday.com/showthread.p...t-or-Snake-Oil

According to Hervey's website, his are:

"Hand made Stainless Steel fuel lines using Teflon hose."

I posted a question inquiring what the core of DPI's braided stainless fuel lines are composed of, but Josh never responded:

http://dmctalk.org/showthread.php?82...400#post131400

Not sure what DMCH's braided stainless fuel lines are composed of - perhaps Dave S could answer this question