Sorry to hear about the leak, Jon, but wow...great job troubleshooting this. If it's in Dave's hands now, we all know it's in good hands!
Sorry to hear about the leak, Jon, but wow...great job troubleshooting this. If it's in Dave's hands now, we all know it's in good hands!
Wow, that was a thorough investigation. Good job on tracking this one down!
Can't take all the credit, Dave is the man when it comes to this stuff. I just hope he can find and fix whatever the issue is, because I swear there is *nothing* visibly wrong with that pump. I have no idea what's leaking!
Edit: I should say that I'm glad I took the time to dig into what was really just a minor annoyance. It's a good lesson to investigate any and all abnormal behavior in your car - you never know when a minor symptom could be hiding a major problem!
Good job diagnosing the issue. Let us know what Dave finds out.
Mine worked really great after the external check valve. But recently, I have been experiencing some mild random cold start issues. Cannot figure out the cause. It stars fine in the "cold" mornings but when I start in the afternoon or after work, I have to crank it for several seconds. But not always. Some afternoon, it starts fine.
Glad that you were able to get this mystery solved!
Hopefully it's a fluke as opposed to being an endemic problem...
Thank you. Your advice and responses have been invaluable in tracing the issue as well. I also hope that it's a fluke and not endemic, but realistically how would anyone know without checking? I put the bad unit in the mail to Dave today and can't wait for the triage and AAR on it, and to get the car running again!Quote:
Originally Posted by NightFlyer
Only way to know other than checking would be to run the tank low and see if they experienced the bucking / fuel starvation issues that you did.
I've run my unit for roughly 4 months and about 5,000 miles. Before putting the car away for winter hibernation, I ran the tank down to practically fumes (less than a gallon remaining) before adding a can of seafoam and 5 gallons of ethanol free fuel and driving home, and didn't experience any bucking / fuel starvation problems - knock on wood. I was actually sweating whether I'd make it to the gas station with the e-free fuel before I completely ran out of fuel and would end up having to walk.
So, I presume that thus far, other than having a faulty internal check valve, my unit is operating properly.
Didn't know you had the newer unit. They do seem to have as many problems as they are supposed to solve! Between leaks, bad check valves, and the level indicator not being accurate, it would seem you are trading one set of problems for another set! Too bad, it could have been done much better. While it is removed you might as well clean the tank out.The good news is you finally have your hands on the problem.
The unit does seem to have some teething problems but I don't think I can agree that it's as bad as the original setup.Quote:
Originally Posted by David T
The tank was sanitized prior to installation of the unit (as required by DMCH for warranty purposes) but you're right - I plan to give it another wipedown while the hole is open all the same. The hope is that nothing was missed the first time but who knows.
I agree that this setup seems to be a big improvement over the original. I haven't had any issues with my fuel sender not reading correctly on the new unit. And DMCH is now selling the new setup with a brass external check valve (with a price tag now of $419 instead of the original $399). Of all the units that have been sold thus far, this is the only one that I've heard of having this type of a leak.
Just my awesome luck... :)Quote:
Originally Posted by kings1527
I also cleaned my tank twice between repairs. Mine was very clean. Didn't really have to clean.
So far it seems it fixed the old problem of the pump buzzing when the fuel gets hot. I think that buzzing was causing most pump failures.
I've been using the unit since it first came out. I am on my 4th pump and it seems to be working now (I also installed an in-line check valve). The problem that I have now is that the sender will always read 1/4 tank too high. So when I fill up my gauge is 1/4 past full. This creates an issue since now when the check engine light comes on I have .5 gallons left (ask me how I know, got lucky deciding to fill up).Quote:
Originally Posted by jawn101
This has been the case with two pumps so far and can't find the issue. Working on replacing the float arm but can't figure out an easy way to remove it to put the replacement one on. If that doesn't solve the problem I am thinking maybe it is an electrical box issue (the box that came with the unit). I have one of the first ones and it is not sealed, I am thinking maybe it is not reading the resistance correctly from possible moisture entering the box? It shouldn't matter if the float arm is bent or not as the contact point on the swing arm for the gauge should read full no matter what, not push the gauge 1/4 past full.
Has another else run into this problem?
I cleaned my tank again today too, since the whole thing was open and the car is immobile anyway. It was very clean, but I did see one chunk of the old boot that I could grab with my fingers - about 0.5mm around maybe? Unfortunately the second I touched it it turned to dust. So I wiped down the whole freaking thing again - no sense cutting corners!Quote:
Originally Posted by Ryan S.
I have the DMCH fuel pump, and I just ordered the usplastic check valve. Now... I can't diss the product, It is nice to have someone selling improved products for these cars, but....... It seems like pretty frequently there is not a whole lot of real world testing of products done by DMCH before they put such things on sale. True to the original manufacturer I guess? I have bought their ball joints, their headlight switch, and now their fuel pump assembly, all of which have proven defective in a time test of actual use.
Now. the headlight switch (so far) has required an uprated fuse to function properly, and the fuel pump (hopefully) will just require this check valve to be reliable, and the ball joints, well... those were just made wrong.
I would love if a new product they intend to sell they would install on a car of theirs for 3 months, drive it 12,000 miles in that time, to verify that they actually FUNCTION properly before they sell them to hundreds of customers, as their test mules.
People who actually drive their D's this stuff just has to work right.
DMCH does test their new products but you have to understand that they cannot spend the time and money to run a thorough testing program for all of the possible conditions. That said you still expect better than what history has shown. My guess as to what is happening with the fuel unit is that most of the time you are replacing the old stuff because it got old and cruddy. If you do not COMPLETELY clean the tank spotless, any dirt will just mess up the new parts. Now you start blaming the new parts you put in, not realizing the dirt ruined them. That doesn't explain leaks. Or the inaccurate fuel level indicator.Quote:
Originally Posted by DeLorean
David,Quote:
Originally Posted by David T
Do you think other dirty fuel-related parts could be part of the overall problem? e.g. spotless tank but the return fuel is coming back in contaminated from other K-Jet components.
Bill
Most people who install the new fuel pump kit have already overhauled the rest of the system, so there should be no contamination to return. New fuel lines are a must in this car at this point. So if your flex lines and filter are new, injectors/WUR/FD are clean, hard lines are flushed, tank is clean and free of 30 year old rubber parts - there should be nothing to come back and gum anything up.Quote:
Originally Posted by Bill6298
Sounds like your fuel system definitely has a way to go, but don't despair - you'll get there! K-Jet is just incredibly sensitive.
Edit: Not to mention that there shouldn't be anything to decay downstream of the fuel filter in the first place. I'm turning the system over in my head and if anything, the fuel that's returned to the tank should be cleaner than the fuel that left it, barring significant pre-existing contamination.
In my mind I believe most fuel system problems begin in the tank. That is where dirt, stale fuel and water get into the system. In that same light, when you start working on the fuel system the tank is where you begin. Theoretically the filter is supposed to trap any dirt but if you have stale fuel it is already downstream of the filter. There is a filter in the CPR and each injector has a screen but by then it is usually too late. If you find, after cleaning the tank, you are getting dirt and junk back into it, it means the system is contaminated and you are flowing the stuff back to the tank from the fuel lines and PPR. Keep cleaning the tank and eventually it should clean up. If you see a tank full of junk the injectors need to be cleaned.Quote:
Originally Posted by jawn101
So, just as an update - Dave and Houston couldn't figure out what was causing the issue, and apparently the unit is going back to the manufacturer. I have a new one inbound, complete with external check valve. Looking forward to installing it and getting rolling again!
Good deal - glad to see them standing behind the product! Thanks for keeping us updated :thumbup:Quote:
Originally Posted by jawn101
Nice. Post some photos of the new pump. I am curious about the location and type of check valve.
It's an inline one, as I understand it - the box should arrive Thursday and I doubt I'll be able to stop myself from installing it immediately. Pictures will definitely follow.Quote:
Originally Posted by Ryan S.
On a somewhat related note, has anyone done an amp-draw test on the new pumps Vs the old type? My guess would be there is probably a savings of an amp or 2 being that it is a more modern pump rather than an old Bosch roller type pump - true? Might be a bit of help to the fuel pump relay lifespan.
Something I would like to know also. If you test the current, do it with the engine running so you have a normal voltage.Quote:
Originally Posted by DeLorean
The best test would be on a car with a nice, clean, well working electrical system. Getting a # off of a car with dirty connections, an old pump, and bad grounds won't mean anything.Quote:
Originally Posted by Bitsyncmaster
Ladies and Gentlemen (who am I kidding) - I am pleased to report that my spewing pump/power loss issue is 100% resolved!!
Before I continue any further it is very important for my own conscience that I start this post by saying that DMCH's new pump was **100% NOT AT FAULT** for the issue, and in fact was working as intended. It may even have saved me from a much bigger headache by doing what it was. I remain confident in the design of this part and very pleased overall with its performance.
That said, let's get on with the diagnosis.
After dozens of emails and a few hours of video chat with the incomparable Dave Swingle over the last few days, the culprit turned out to be none other than...
http://dmctalk.org/attachment.php?at...5&d=1391306960
http://dmctalk.org/attachment.php?at...6&d=1391306967
The high-pressure accumulator hose! As you can see in those photos (crap quality, but we all know that compartment is no easy place to see or photograph) the OEM hose had thermoformed a very hard kink in it. The pressure from the fuel pump must have been inflating it just enough for some gas to flow, enough to run the engine - but it was certainly a major restriction in the system. The weird thing was that the fuel pressure (tested with a K-Jet kit on loan) was 100% dead on at the fuel distributor. But that was at idle, with no way to test it under load.
http://dmctalk.org/attachment.php?at...7&d=1391306973
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. I have upgraded every one *except* these two at the accumulator, due to the difficulty of it. Look what that got me. The hilarious thing was that I had purchased new lines for this job and just had them waiting on my shelf. Very convenient that the fix ended up being a net $0 in parts!
Anyway, here's the beautiful result of all that work...
https://www.youtube.com/watch?v=fm95eIWHdEg
As you can see the pump runs smoothly and quietly, with no spewing. The baffle quietly fills up and overflows, just like it's supposed to. The sputtering under load with low fuel is gone.
Huge thanks to David Proehl, Clint W, Ryan S and especially Dave at DMCMW. Have you ordered anything from them lately?
You have inadvertently settled another argument from long ago. The baffle will be full to the top all the time until the tank is dry.
This was interesting. . . .
A bit more detail - with the fuel link kinked, the "excess" fuel blew out through a relieve valve at the top of the pump. The fuel that got through the kink was enough to run the engine, usually quite well. The relieve valve excess came out with such force that it didn't land back in the baffle. There wasn't the usual return flow from the engine to refill the baffle due to the kink as well. The relieve valve is there to protect the pump in the event of, well, a kinked line or plugged filter.
Therefore the baffle ran low when the tank was low, effectively creating a hole in the pool of gasoline.
I contend that he would have noticed that the car ran out of power (gasoline) at wide open throttle very hard acceleration near redline, but he doesn't drive the car that way.
BTW - for future reference - a close to plugged fuel filter will cause exactly the same problem.
PS we also has some fun comparing the view out the front door.
Great additions, I should have included more of that. My mind is sort of soft from all the fumes today. Tomorrow I am going to verify that my mixture is still correct (this repair may have enriched it a bit) and then hit the highway with some gusto. See how she does. I have since filled the tank back up (took 13.2 gallons, so that should show just how empty I ran it) and it is driving great!!Quote:
Originally Posted by DMCMW Dave
Yes... we have very different views from our garages right now. 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.Quote:
Originally Posted by jawn101
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.Quote:
Originally Posted by jawn101
Fantastic to know the new pump was not at fault.
WOW - What a completely unexpected end to that mystery. Glad it was finally solved and that the fix was cheap :thumbup:
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?Quote:
Originally Posted by NightFlyer
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.Quote:
Originally Posted by Bitsyncmaster
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.
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.Quote:
Originally Posted by 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.Quote:
Originally Posted by DMC5180
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 :smile: