DMCH fuel pump

[lindbergh]

Has anyone with a DMCH fuel pump PN#107000 performed the mod explained by SB-07-10/2017. The inertia switch when activated does not cut off the fuel pump. The fix calls for cutting the secondary ground on the fuel sending unit side (3 wire connector). Anyone cut this? and did it have any effect on the way the fuel gauge works?

Thanks.

[dmcnc]

No effect on the gauge. Just make sure you're cutting the DMCH fuel pump module side and not the car's wiring harness in case you ever decide to change to another set-up (i.e. OEM). I'm not a fan of cutting any wiring, so I just pulled it out of the connector and taped it up.

[lindbergh]

No effect on the gauge. Just make sure you're cutting the DMCH fuel pump module side and not the car's wiring harness in case you ever decide to change to another set-up (i.e. OEM). I'm not a fan of cutting any wiring, so I just pulled it out of the connector and taped it up.

OK, thanks. I am not a fan of cutting wires also so I will use your method.

[Josh]

it certainly is a laughable "fix" to cut up the wires on your $420 fuel pump setup.

I have come to learn it is the least of ones problems, the hoses disintegrate from the inside out and the cheap Chinese fuel pump dies before 30k miles.

[dmcnc]

Did you end up replacing yours for another style pump?


it certainly is a laughable "fix" to cut up the wires on your $420 fuel pump setup.

I have come to learn it is the least of ones problems, the hoses disintegrate from the inside out and the cheap Chinese fuel pump dies before 30k miles.

[Chris 16409]

You can get a made in Mexico AC Delco pump that is conpatible. I found it hard to find any that were made in the US anymore.

[DMC-81]

No effect on the gauge. Just make sure you're cutting the DMCH fuel pump module side and not the car's wiring harness in case you ever decide to change to another set-up (i.e. OEM). I'm not a fan of cutting any wiring, so I just pulled it out of the connector and taped it up.

That's the preferred ( neatest) approach I heard of as well.


it certainly is a laughable "fix" to cut up the wires on your $420 fuel pump setup.

I have come to learn it is the least of ones problems, the hoses disintegrate from the inside out and the cheap Chinese fuel pump dies before 30k miles.

That's unfortunate Josh. I don't have near that many miles on mine, but I just passed 5 years with my module installed. It was installed at the time I bought the car, so I didn't experience the downsides of the OEM setup.

So far, it's been running flawlessly, hoses included. Although, admittedly, I use non-ethanol fuel and only once did I add a bottle of Techron.

In terms of longevity, I wonder about the capacity (psi and gph) of the module versus what your LS requires? (I'm sure you sorted through that).

:cheers:

[FABombjoy]

So far, it's been running flawlessly, hoses included. Although, admittedly, I use non-ethanol fuel and only once did I add a bottle of Techron.
It's not the composition of the fuel - the hose provided is E85 rated. It's installing the hose on barbed fittings which the manufacturer specifically recommends against.

[Josh]

That's the preferred ( neatest) approach I heard of as well.



That's unfortunate Josh. I don't have near that many miles on mine, but I just passed 5 years with my module installed. It was installed at the time I bought the car, so I didn't experience the downsides of the OEM setup.

So far, it's been running flawlessly, hoses included. Although, admittedly, I use non-ethanol fuel and only once did I add a bottle of Techron.

In terms of longevity, I wonder about the capacity (psi and gph) of the module versus what your LS requires? (I'm sure you sorted through that).

:cheers:

The pump capacity is adequate. Kjet is more demanding on the fuel pump due to the high pressure required than the LS.

[DMC-81]

It's not the composition of the fuel - the hose provided is E85 rated. It's installing the hose on barbed fittings which the manufacturer specifically recommends against.

Hi Luke. Yes, I read the thread on that. However, I'm sure we are not the only people using these fuel injection rated hoses with barbed fittings. I also think it's something to figure out.... nobody likes to take a ride of shame home and/or or have a fire risk after all.

Setting the barb issue aside for a minute, I see 2 concerns:

1) Figuring out what is causing the hoses to soften inside: If the hoses are E85 rated, and the ethanol is causing the softening, then that's a quality/design issue with the hose manufacturer. Maybe it is caused by fuel additives like Techron? I'm not sure, but I think we need to see if these are a few isolated incidents with mitigating factors or a general problem. A deteriorated hose will fail on any type of fitting.

I choose to use non-ethanol fuel in the DeLorean not necessarily to protect these new E-85 rated hoses, but other components in the fuel system that I know were built before bio-fuels came about, and because I had to replace the whole gas tank on my daily driver because the supposedly E85 rated main gasket disintegrated.

2) Figuring out what is causing the hose(s) to back off? Is it the above mentioned softening/deterioration? Is it because they weren't tightened to spec? When I did my fuel accumulator (which has the same Gates barricade hoses) and when I added a check valve to the fuel module, I ensured I got fuel injection clamps, installed the clamps in the middle of the barb portion, and torqued them to the clamp type spec.
As mentioned above, I have not had any problems yet. I did the same process with my cooling system and never experienced any leaks. Not one drop, and no need to go around to re-tighten hose clamps.

My point is, we should figure out whether we have a design issue, improper installation, or some other external factor.

[FABombjoy]

I'd consult directly with Gates technical department and explain that a DeLorean runs 5 bar of system pressure w/ Barricade hose installed on barbed fittings originally used for PTFE hose. Barricade was designed for EFI @ 3 bar fuel pressure (or less, depending on MAP) to be installed on beaded fittings. I'm thinking they'll steer you toward a nylon or PTFE product :D

My hoses were installed as properly as possible. After less than 2 years, one backed right off the barb and the other wasn't far behind. You could push it back on to the barb with no effort. Since I didn't care for a repeat experience and am not an investor in DMCH I went to nylon hose and called it a day. I have the parts for an accumulator delete mod and once that's done, no more rubber anywhere in the fuel system!

[DMC-81]

I'd consult directly with Gates technical department and explain that a DeLorean runs 5 bar of system pressure w/ Barricade hose installed on barbed fittings originally used for PTFE hose. Barricade was designed for EFI @ 3 bar fuel pressure (or less, depending on MAP) to be installed on beaded fittings. I'm thinking they'll steer you toward a nylon or PTFE product :D

My hoses were installed as properly as possible. After less than 2 years, one backed right off the barb and the other wasn't far behind. You could push it back on to the barb with no effort. Since I didn't care for a repeat experience and am not an investor in DMCH I went to nylon hose and called it a day. I have the parts for an accumulator delete mod and once that's done, no more rubber anywhere in the fuel system!

Thanks Luke for the detail on Gates hoses. Not to argue here, but wasn't a factor in your situation applying 6? bottles of Techron at high dosage levels to address an engine issue?

I guess that's my point. I wonder why your hoses failed in 2 years, and mine are still good after 5 (with 5 bar pressure and all). I'm not pointing fingers, don't get me wrong. Rather I'm just trying to understand the cause, and the likelihood of an immediate need to change the hoses.

[opethmike]

It was zombies.

[FABombjoy]

Not to argue here, but wasn't a factor in your situation applying 6? bottles of Techron at high dosage levels to address an engine issue?
Just some carbon cleanup from failed turbo oil seal. I'd think that Techron would be something to consider if my case were isolated. There have been several other reports of the same failure both here and on FB groups.

Techron has been around forever. From a liability standpoint if Techron were harmful to fuel hose I would think it would be well established by now. A cursory search for terms like "techron hose damage" and "injector cleaner hose damage" doesn't really turn up any results, anecdotes, etc.

From the brochure: "Beaded stems are recommended for rubber hose. Barbed stems are for use with plastic tubing only, due to the sharp ferrules and serrated teeth."
This suggests that clamp torque may have a larger effect on time-to-failure. More torque -> more liner damage. You might have hit a sweet spot when installing yours. Or maybe the serrations on your OEM hose fittings have more of a rounded edge. Lots of variables to consider if you want to perform a comprehensive study :)

[Bitsyncmaster]

You could file or sand any sharp edges off a barbed fitting and result in more of bead.