DMCH new style fuel pump thoughts.

[hippieman9]

I’m curious about the cause of this as well. How many times did you use Techron additive over the 2 years, or was it in Chevron fuel? These hoses are rated for bio fuels, but I wonder if the Techron is causing the issue?

I have been running the DMCH fuel module with Gates Barricade hoses since 2013 and, a new accumulator with these hoses since 2015 without any issues. However, I strictly use non-ethanol fuel.

Are the Gates hoses you speak of the ones that come with the kit? If not is this recommended?

[DMC-81]

Are the Gates hoses you speak of the ones that come with the kit? If not is this recommended?

Yes, I believe Gates Barricade (for fuel injection) hoses still come in these kits, unless a change was made since I bought them. I would contact DMC to verify what hoses are included.

[David T]

I bought a 6 pack of Techron in March 2016 and fed it in at high dosage levels (one per tank). A bad turbo rebuild led to prolonged oil injection. This was a long-term strategy after a very thorough top-end cleaning.

I'm sure there was fuel w/ techron sitting in the lines for prolonged periods.

Interesting here:
http://www.napabeltshose.com/~/media...20Brochure.pdf


So there it is - not recommended for barbed fittings.

Techron is not meant for regular use and certainly not meant to be left in a non-running car for prolonged periods. It is to be put into a filled gas tank and used all up right away maybe once a year at most unless you put a lot of miles on your car. If one dose doesn't fix it you probably need the fuel injectors pulled, cleaned, and tested.

[cis6409]

This has been an annoying issue for me to, I have the same issue with the fuel pump hoses. They are ethanol resistant rated as well and got them from both Ed and my local quality parts store but they don't last, especially if the car is not driven frequently enough.
I' now change them every couple of years to keep ahead.

I'm running stock fuel pump set up.

Unfortunately here in Ireland (not sure about northern Ireland) all unleaded petrol for sale is ethanol based..
The metering heads don't like the ethanol to.

If you drive it reguarly thru out the year with fresh fuel the problem is minimised

Shane

[FABombjoy]

Techron is not meant for regular use and certainly not meant to be left in a non-running car for prolonged periods.

Can you site a source for this? I read through the literature and can't find anything to support this claim.

If one dose doesn't fix it you probably need the fuel injectors pulled, cleaned, and tested.

I was using Techron mainly to aid in cleaning valves and piston crowns. Bad turbo rebuild caused prolonged oil injection. That issue has been resolved.


Back to the actual reason for failure:

Gates Barricade hoses are not intended for use on barbed fittings:
http://www.napabeltshose.com/~/media...20Brochure.pdf

[David T]

Techron is meant for use mainly as a fuel system cleaner. To clean the combustion chambers there are top end cleaners for that. If the deposits are really bad you are probably better off pulling the heads and removing the deposits mechanically. While it doesn't explicitly say it in the literature about overuse and leaving it in the lines, IMHO Techron is very volatile and is meant to loosen accumulated deposits inside the fuel system and injectors. It can't be doing any good for the rubber so the less time it is in contact with the rubber the better. Pulling and "reading" the spark plugs can give you some indication of what's going on in the combustion chambers. If you have a borescope even better.

[FABombjoy]

Techron is meant for use mainly as a fuel system cleaner.

Reference: https://www.techronclean.com/en_us/faq.html

Q: What does Techron do?
A: Techron targets carbon deposits, breaks them up and clears them out of your car’s system, and keeps vital engine parts clean with continued use.

That's really enough OT about fuel additives.


Solving issues surrounding rubber hoses & modern fuel modules:

A modern plastic fuel line should be used, nylon or PTFE. These can be installed on the existing K-jet barbs (see photo) without too much effort using 5/16" (8mm) tubing and assembly oil. Will need 90 degree quick disconnects at the fuel pump due to clearance with underbody.

Nylon-Kjet.jpg

If you have K-jet, the check valve needs to be in line with the supply hose. DMCH supplied valves have excessive OD for 5/16" tubing so a different style of valve is necessary. There are barbed check valves out there, 6mm OD valves will match the tubing ID. Have no idea which brands are quality as I've deleted the valve from my EFI setup.

The tubing needs to be indexed as it isn't going to allow for any rotation. Add the QD connectors on the bench first, then connect to pump and route / trim the lines. Once nylon has been seated onto the barb it will be nearly impossible to rotate.

Once everything is clocked into place the tubing should be clamped using proper earless EFI clamps. In my tests using Dorman fuel tubing, I was able to pull on the tubing hard enough to distort the plastic without the hose releasing from the barb. Dorman does recommend clamping the tube, though.

[FABombjoy]

Posted my own fix for the rubber line issue in this thread:

http://dmctalk.org/showthread.php?16...l=1#post236447

[hippieman9]

Posted my own fix for the rubber line issue in this thread:

http://dmctalk.org/showthread.php?16...l=1#post236447

This is great! Is there any specifics for the check valve? Is it better placed near the pump or the hard line? Also jus for the feed side?

[FABombjoy]

Feed side only. Needs to be rated for gasoline fuel injection.

Without the check valve the accumulator spring will decompress and drain fuel back into the tank through the fuel pump, causing a loss of rest pressure. Since deleting the check valve I can now hear this at every shutdown (a slow "bong.... bong.... bong... noise from the center of the frame). If you have EFI it doesn't matter since they don't vapor lock like K-jet.

If you have a hot start relay it honestly might not matter either. The HSR will help purge the fuel lines via the CSV at every startup which helps eliminate the rest pressure portion of the accumulator's job.