DMCH new style fuel pump thoughts.

[hippieman9]

Ok everyone, I'd like to know your thoughts, especially if you have installed the all in one fuel pump from DMCH. I am currently looking at my options of upgrading to the new pump or rebuilding what I currently have. Since this is a part that seems to be prone to failure, I'd like to have it as reliable as possible.
I took my car out today for 150+ mile cruise after finishing a bunch of work and I had the A/C on as it was about90 or so degrees in North Carolina today. When I would stop at a red light I could get a fuel smell in the drivers compartment. So I removed the spare and removed the access panel to look at the fuel pump. ( seems like a good place to start since this is one area I have not messed with yet since purchasing the the car.) also being that the fuel tank is in the front only seemed logical that that is where I was getting the smell. cooling fans running with A/C on + Fuel leak= smell in the car. Also when I would start driving the smell would go away.
any way this is what I found .....5726257263
Looks as if the fuel pump seal is leaking , and has been for a while. Also I have noticed that the pump is getting louder and louder . It calms down when you fill it with fresh cool fuel. But it has me concerned that the pump is on the way out. .... So.... With all that said, I am contemplating going with DMCH's new all in one style pump. But I'd like to hear some real time reviews on it. any problems? how's it work? it is worth the up grade?

I'm listening! Thanks!

[Kevin 02530]

I installed mine a little over a year ago. Easy installation just had to modify a few lines and install the wiring harness. Otherwise I’m very happy and have had no problems at all with it. I would definitely go this route again even though it’s a little more expensive that the original setup.


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[hippieman9]

I installed mine a little over a year ago. Easy installation just had to modify a few lines and install the wiring harness. Otherwise I’m very happy and have had no problems at all with it. I would definitely go this route again even though it’s a little more expensive that the original setup.


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I was just pricing it out and actually Delorean Go has a kit with an original style pump and its the same price as the new style. Because if I'm in there to replace the pump, I'm gonna replace everything. Ethonal is horrible on plastic and rubber components, Also I forgot to mention the inner boot on my pump, The one that is below the "cap" or top rubber boot, the seal that also seals the tank if you will , is very tacky and gooey. I believe this is why mine is leaking.

[Kevin 02530]

My boot was totally rotted out https://uploads.tapatalk-cdn.com/20180711/15b4f4e4e47b7ec400f59bd0f76e1a58.jpg


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[FABombjoy]

Like:
-Quiet
-Reasonably easy install
-All-in-one pump/baffle/sender is wayyy less Rube Goldberg than factory ship in a bottle.
-Doesn't squeal when hot like the OEM pumps seem to do chronically.

Meh:
-Fuel gauge only reads when pump is running due to gauge adapter circuit only receiving power from fuel pump relay. Solving this would require either running switched +12 to the pump or modifying the harness near the gauge cluster.

Dislike:
-Had hose failure last weekend. Internal lining softened causing hose to release from supply/return K-jet hose barbs. Hose was marked as rated for modern fuels but went soft after 2 years. Was it ethanol? Prolonged fuel-to-hose contact due to in-line check valve? Techron? Who knows.
I'm going to make some nylon fuel hoses but I don't need the check valve. DMCH should R&D an improvement from nylon or PTFE with appropriate in-line valve or select a hose that is more compatible with barbed fittings.

-Field servicing of pump itself is reportedly not easy and there have been a few failures reported. Would like to know if Walbro could replace OE unit.

[David T]

As nice as the newer style unit is from DMCH it has not been without it's own set of problems. Kind of like trading one set of problems for another. If your fuel sending unit is bad too the DMCH unit is tempting. Otherwise it is probably cheaper to just replace the original parts with new. The rubber doesn't last forever especially with Ethanol. Once the pump starts making loud noises it is on it's way out so if you don't replace it right away, at least get one so you have it. Be careful with the screen and baffle parts, the stud in the tank and when you do this you should drain the tank and wipe it out so there is no dirt or goo. Acetone works great but be careful, don't do it in a garage and use a respirator. Refer to Service Bulletin ST-30-12/81. If the cover boot and fuel pump boot are sticky, gooey, or soft, just replace them and the pick-up hose. Sticking a long spring inside the hose is a good idea. Find one in a hardware store that is used for screen doors.

[SS Spoiler]

DMC pump is working great once I reversed the
feed and return lines....

[Ron]

Like:
-Quiet
-Reasonably easy install
-All-in-one pump/baffle/sender is wayyy less Rube Goldberg than factory ship in a bottle.
-Doesn't squeal when hot like the OEM pumps seem to do chronically.

Meh:
-Fuel gauge only reads when pump is running due to gauge adapter circuit only receiving power from fuel pump relay. Solving this would require either running switched +12 to the pump or modifying the harness near the gauge cluster.

Dislike:
-Had hose failure last weekend. Internal lining softened causing hose to release from supply/return K-jet hose barbs. Hose was marked as rated for modern fuels but went soft after 2 years. Was it ethanol? Prolonged fuel-to-hose contact due to in-line check valve? Techron? Who knows.
I'm going to make some nylon fuel hoses but I don't need the check valve. DMCH should R&D an improvement from nylon or PTFE with appropriate in-line valve or select a hose that is more compatible with barbed fittings.

-Field servicing of pump itself is reportedly not easy and there have been a few failures reported. Would like to know if Walbro could replace OE unit.
That mirrors my thoughts on them...I would add that "10% of time" there is a clearance problem with the inspection cover no matter how it is oriented.

[81dmc]

Go with the DMCH all in one module as it's a great modern alternative.


Just don't use the supplied hoses though...

[Henrik]

...I would add that "10% of time" there is a clearance problem with the inspection cover no matter how it is oriented.

I am (was) one of the 10%. No matter how I indexed the pump, it still interfered by a good 1/4" with the inspection cover. I also of course made sure there was nothing causing the tank to not sit as low as it should, etc. My work-around was to add a gasket around the inspection cover which added an ever so little amount of clearance between it and the pump which allowed me to install the cover (with quite a lot of brute force I might add). The cover still sits hard up against the pump which is not ideal.

Other than that I can highly recommend the new style DMCH pump. I have run it since 2013 and it has worked flawlessly with no smell in the cabin. We did have some concerns during the engine swap as to whether it had the capacity to keep up during high load conditions - but - no issue whatsoever.

[hippieman9]

Go with the DMCH all in one module as it's a great modern alternative.


Just don't use the supplied hoses though...

What hose do you recommend, and why?

[FABombjoy]

That mirrors my thoughts on them...I would add that "10% of time" there is a clearance problem with the inspection cover no matter how it is oriented.
Yes! I forgot about that completely. Same issue here and took a grinder to the back of the cover to fix it.

The interference was at the plug on the pump and I used a file on the corner of the plug body to help things fit but preserve the weatherpack design. This is the best pic that I have showing the mod:
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This was the situation after the July 1 car show:
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The offending hoses which started life completely flush against the hex section of the barbed fitting
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[Ron]

Yes! I forgot about that completely. Same issue here and took a grinder to the back of the cover to fix it.

Mine needed a little more room than that. So I took a heat gun to the cover..

[Henrik]

Mine needed a little more room than that. So I took a heat gun to the cover..

Great idea. I will try that.

[ssdelorean]

I'm a fan of the original setup. It seems there are less parts than the new one that could potentially go wrong. I also have had great success with the original setup. I have over 216,000 miles on my car and am only on my 2nd fuel pump. On the flip side, I have replaced the fuel pump boot and cap about 3 times due to fatigue of the rubber and shinkage of the cap.

My first and original to the car fuel pump only buzzed on extremely hot days when getting down to a quarter tank. My replacement pump seems to buzz it normal temperatures but more so in the extreme heat.

Sometimes I get the seepage around the top of the boot and/or cap but that is usually due to over filling the tank and/or on hot to cold days where temps flux, the pressure expands the tank and it comes out at the weakest area. I have also had the tank leak out of the top one time removing it from winter storage out of the garage because of the pressure.

[Chris 16409]

It's interesting people are having issues with the Gates Barricade fuel injection hose. I've been using it for a while now. I used to get this injection hose by Good Year, but O'reillys stopped carrying it. I have been using a GM fuel pump from AC Delco(#MU1777). It looks very similar to the unit that DMCH is using. My fuel sender is still good, so I am not using the built in float fuel sender. You can get the pump at AutoZone for around $180 with LIFETIME warranty. It seems to be holding up nicely. You will still need to buy a check valve, but you can get them for around $15.

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[hippieman9]

Very interesting thoughts on both sides of the spectrum. Thank you!

[81dmc]

I have been using a GM fuel pump from AC Delco(#MU1777). It looks very similar to the unit that DMCH is using. My fuel sender is still good, so I am not using the built in float fuel sender. You can get the pump at AutoZone for around $180 with LIFETIME warranty. It seems to be holding up nicely. You will still need to buy a check valve, but you can get them for around $15.

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Nice find!

If my DMCH module ever goes, that looks like a good replacement.

[DMC-81]

Dislike:
-Had hose failure last weekend. Internal lining softened causing hose to release from supply/return K-jet hose barbs. Hose was marked as rated for modern fuels but went soft after 2 years. Was it ethanol? Prolonged fuel-to-hose contact due to in-line check valve? Techron? Who knows.
I'm going to make some nylon fuel hoses but I don't need the check valve. DMCH should R&D an improvement from nylon or PTFE with appropriate in-line valve or select a hose that is more compatible with barbed fittings.

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.

[FABombjoy]

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/NAPA/Documents/NAPA_Barricade_4%20Page%20Brochure.pdf


Q: What are the recommended clamps for fuel hose line?

A: J2044 is the SAE Quick Connect Coupling Specification for Liquid Fuel and Vapor/Emissions
Systems. Any quick connect, worm gear or spring-loaded mechanical couplings used
with Barricade should meet this spec. Beaded stems are recommended for rubber hose.
Barbed stems are for use with plastic tubing only, due to the sharp ferrules and serrated teeth
So there it is - not recommended for barbed fittings.

[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/NAPA/Documents/NAPA_Barricade_4%20Page%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/NAPA/Documents/NAPA_Barricade_4%20Page%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.

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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?16618-Possible-concern-with-DMCH-fuel-module-hoses&p=236447&viewfull=1#post236447

[hippieman9]

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

http://dmctalk.org/showthread.php?16618-Possible-concern-with-DMCH-fuel-module-hoses&p=236447&viewfull=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.

[hippieman9]

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.

I have DaveÂ’s RpM relay. So youÂ’re saying a 6mm check valve? Like this? https://www.amazon.com/Return-Check-Petrol-Diesel-Aluminium/dp/B06XK5CSS4/ref=mp_s_a_1_1?ie=UTF8&qid=1531515386&sr=8-1-spons&pi=AC_SX236_SY340_QL65&keywords=6mm+fuel+check+valve&psc=1

[FABombjoy]

No, that one is probably cheap garbage. Look toward Jegs or Summit and see if they have anything. You can adapt just about anything to work, so quality should precede fitting style.

Do you have Dave’s hot start relay? Thats what I’m referring to. I tested a lot of stuff with kjet but never the hot start relay function.

[Bitsyncmaster]

The problem with loss of rest pressure quickly is the injector hoses fill with bubbles. You can prime the fuel system but that will not do anything for the bubbles in the injector lines. The air plate has to move down to start purging those lines.

The hot start relay will fire the CSV and most likely get your engine turning fast enough to move that air plate down a little. But it can take a minuet or two to really clear all the injector lines of bubbles.

Hence the hot start relay is really not the correct fix for rest pressure falling to quickly. My RPM relay can be jumpered to extend rest pressure for 3 more hours but you need to hold rest pressure for at least one hour for that to work.

[hippieman9]

No, that one is probably cheap garbage. Look toward Jegs or Summit and see if they have anything. You can adapt just about anything to work, so quality should precede fitting style.

Do you have Dave’s hot start relay? Thats what I’m referring to. I tested a lot of stuff with kjet but never the hot start relay function.

No I don't have his Hot Start Relay, Just the Rpm Relay.

[FABombjoy]

The hot start relay will fire the CSV and most likely get your engine turning fast enough to move that air plate down a little. But it can take a minuet or two to really clear all the injector lines of bubbles
Ah, gotcha. Never tried it and I definitely would keep the accumulator for K-Jet. Even if you could cure the hot-start without an accumulator, transient fuel response would suffer.

Seems like a lot of OEMs came up with solutions for K-jet hot starts. Mercedes added a solenoid to force the plate to move if long cranking times were happening:
http://www.peachparts.com/shopforum/attachments/vintage-mercedes/18274d1084287444-solution-m110-warm-start-problem-hot-startlores.jpg

Some Porsche 928 Euro had a hot-start valve that drops control pressure to 0 when cranking.

[Ron]

Ah, gotcha. Never tried it and I definitely would keep the accumulator for K-Jet. Even if you could cure the hot-start without an accumulator, transient fuel response would suffer.

Seems like a lot of OEMs came up with solutions for K-jet hot starts. Mercedes added a solenoid to force the plate to move if long cranking times were happening:
http://www.peachparts.com/shopforum/attachments/vintage-mercedes/18274d1084287444-solution-m110-warm-start-problem-hot-startlores.jpg

Some Porsche 928 Euro had a hot-start valve that drops control pressure to 0 when cranking.I'm thinking you deserve the Daily DMCTalk Research Award. :thumbup:

[FABombjoy]

I'm thinking you deserve the Daily DMCTalk Research Award. :thumbup:
Trivial research anyway :) I really wanted Turbo K-jet to work well and read a lot of service literature from Volvo, Porsche, and other companies that ran K-jet for years after DMC ceased operation. It's interesting how OEMs had many different ways of improving the mousetrap.

[hippieman9]

For anyone interested I just finished installing the new DMCH fuel pump. I noticed that it has a plastic cap now for the OE style level sender and comes with a check valve in the feed line. I took this a step further and installed nylon fuel line instead for using the rubber (it seems as though that was the major issue with this style pump.) install was easy. Cleaned the fuel tank, but it wasn’t very dirty because my car is driven. Here are a couple pics of the final install.5747857479

[FABombjoy]

Did you get 5/16" nylon line to fit on the provided check valve? If so, tip of the hat, I never would have expected it to fit!

[hippieman9]

Did you get 5/16" nylon line to fit on the provided check valve? If so, tip of the hat, I never would have expected it to fit!

YES!! after many, many tries and fails. LOL I found that I held the nylon fuel line in my Brake tubing flare tool, clamped it in the vise, used a hair drier to warm up the tube, then used needle nose pliers to open up the tube a little, then taped the check valve in with a hammer, slowly. I found that you have to have less tubing than you need on the heat side for the clamp, then move it out a little at a time or the tubing will, bend and kink. Wasn't easy thats for sure, and I was bummed I couldn't get any clamps on the check valve, but it is not leaking so, Fingers crossed!

[Ron]

...I was bummed I couldn't get any clamps on the check valve, but it is not leaking so, Fingers crossed!
I'm missing something??? Why can't you open them all the way up and install them even now?

[hippieman9]

I'm missing something??? Why can't you open them all the way up and install them even now?

Well, I could of used worm drive style clamps, But I was using single ear clamps, and they are either too small to fit over the barb on the check valve, or too big and wont crimp tight. So I didn't put anything on them and they seem to be just fine. The barb is very big on the check valve.

[NightRider]

Having already replaced the fuel pump in my car 3 times in the last 15 years, I decided to have my mechanic put in the modern replacement from DMCH. Hopefully it will be less prone to failure.

[hippieman9]

Having already replaced the fuel pump in my car 3 times in the last 15 years, I decided to have my mechanic put in the modern replacement from DMCH. Hopefully it will be less prone to failure.

Where in NC are you located?

[NightRider]

I'm in the Charlotte area. I bought my car from a guy in New Bern about 15 years ago.

[hippieman9]

I'm in the Charlotte area. I bought my car from a guy in New Bern about 15 years ago.
Cool, I'm in the Mebane / Burlington area. Not too far from you.

[dmcnc]

Hi Chris - have you checked your fuel pressure with this pump? I thought most of the GM pumps only produced up to 70 PSI


It's interesting people are having issues with the Gates Barricade fuel injection hose. I've been using it for a while now. I used to get this injection hose by Good Year, but O'reillys stopped carrying it. I have been using a GM fuel pump from AC Delco(#MU1777). It looks very similar to the unit that DMCH is using. My fuel sender is still good, so I am not using the built in float fuel sender. You can get the pump at AutoZone for around $180 with LIFETIME warranty. It seems to be holding up nicely. You will still need to buy a check valve, but you can get them for around $15.

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[FABombjoy]

Hi Chris - have you checked your fuel pressure with this pump? I thought most of the GM pumps only produced up to 70 PSI
The problem with a quoted value is that 70 PSI is only one dot on a 3D graph: Flow -vs- Pressure -vs- Voltage

Almost any EFI pump will have adequate fuel flow to meet the HP requirements of a stock / modified PRV. Many pumps can supply 100PSI or more but the volume of fuel drops quite a bit. The nature of K-Jetronic & our wiring adds a few confounding variables:
-Additional restriction at check valve
-Additional restriction at accumulator
-Additional flow required to manage hydraulic system control (fuel is both the consumable and the regulatory fluid)
-Crap connectors / compromised grounds means measured voltage drops at the pump, further reducing capacity
-Hot fuel

Some of these modules seem to have short lifespans possibly due to operating right at the end of tolerance. It would be nice to have an option with a name attached - AEM, Walboro, Aeromotive, etc. that had some weight / history to the name. They typically provide a full specification sheet of vol/pres/volts.

[dmcnc]

Bosch would be the closest, but it's difficult to track their specs on modern pump modules. Usually the answer you'll get is STOCK or OEM.





Some of these modules seem to have short lifespans possibly due to operating right at the end of tolerance. It would be nice to have an option with a name attached - AEM, Walboro, Aeromotive, etc. that had some weight / history to the name. They typically provide a full specification sheet of vol/pres/volts.

[FABombjoy]

Right? It's basically like "fitness guaranteed for application", and the guts could change at any time. A DMC suitable fuel module could be one supplier change or cost reduction away from slipping out of specification. Just one more compelling reason for people to ditch K-jet and switch to EFI :D