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Lots of things can cause the engine to run for several seconds and then die (typically a vacuum leak). This at least tells that the cold start injector is most likely working as it shouldOriginally Posted by dreiermann
I wonder if the test-rig valve was opening all the way, or maybe it's too small.
Maybe you can post pics and describe how you connected and used the test-rig?
Last edited by epmedia; 01-24-2017 at 02:40 AM.
Tbd
Member
No, that's the steel valve body. It only has 2 passages for fluid to flow in and out of the valve. It can be moved within the aluminum WUR housing but should not be removed.
Where did you disconnect the return line?
I think it's best to back flush/clean the WUR with the valve disassembled the way the OP did. There is no restriction in the valve that way.
Member
I 100% agree after thinking about the design in more depth.
How you been Josh! Great to see you posting, we need your expertise around here every now and then
Tbd
Member
Doing well, how bout you? Life's responsibilities with 4 daughters now have taken over for the last few years but I'm picking the e21 project back up. The cylinder head is at the machine shop!
Member
OK, finally back to working on the car after too many days full of non-car activities.
Today I set up the pressure test again, and got a different result - 40 psi for cold control pressure, 65 psi for system pressure. And I may have discovered why it was reading the same for both cold and system pressure before - after I closed the valve to read system pressure (when it went up from 40 to 65), I opened the valve again but the gauge did not go back down to 40, even when pressing the bleed button on the gauge. That seems wrong, and if the gauge is not letting go of pressure then I don't know how I would do the leak-down test.
After the test, I removed the gauge and hoses, re-connected the power to the WUR and the cold start injector, replaced the motor relay, and tried to start the car. This time, it was in 'fail' mode, running for a few seconds perfectly fine, then it died. I kept trying to start it, maybe 15 or 20 times to see if the run time would be longer or shorter each time, but it did not seem to change. Given past experience, the next time I try to start it, it will probably run just fine and not die.
The way it alternates between 'no problem' and 'die after 4 seconds', I am wondering if it could be something that is sticking mechanically. The pivot points inside the WUR did not seem sticky at all, the grease was still good and I put on new grease just because I was in there. I thought about the metering plate, but I don't think that the car could run so smoothly for four seconds if the metering plate was not moving. Could it be an issue with the fuel distributor - the plunger in the middle not sliding like it is supposed to? Getting hung up sometimes but not other times? Or is the WUR the only thing that could cause the high control pressures?
Member
I tried starting the car again today, it was still in fail mode. I checked the air metering plate, it moved freely. I tapped the fuel distributor (in case the piston in the center was hung up). Then I tried to start it again. Same fail mode.
So in order to effectively eliminate the WUR from the equation, I connected the test hoses again but without the gauge. This allowed me to valve off the WUR from the control pressure line to the fuel distributor. With the WUR valved off, the car would start and run without dying. It didn't idle well, but it ran. At least that eliminates the fuel distributor as an issue.
Now, considering that I was able to lower the control pressure by blocking the line to the WUR, that seems to indicate that the WUR is flowing too much fuel. No amount of cleaning will fix that, and it already looked clean to begin with. Is there any way to bring these things back into spec, or do I have to shell out $350 for a new one, or gamble $80 on a used one?
Thanks!
UPDATE
Immediately after posting that (above), I was thinking about how I had previously checked for return line blockage - with the return side of the WUR draining directly into a gas can, I saw no change in control pressure. BUT - realizing that the gauge was not letting go of the higher pressures, I decided to do a running test - I routed the return side of the WUR to a gas can again, then started the car. It ran great! Connected it back to the WUR, it ran fine at first, then I shut it down and re-started, and it went back to fail mode. Hopefully I will be able to replace or un-clog the return line - first I will have to trace it. It looks like it goes from the WUR to the fuel distributor, and I am guessing that one of the two large braided lines at the fuel distributor is the return (and the other is the supply). If anyone has dealt with a clogged return line before, please let me know how you resolved it. Thanks, everyone!
Last edited by dreiermann; 02-02-2017 at 08:54 PM.
Member
You cannot use a gauge with a pressure release valve while testing between system and control pressures because this type of gauge maintains a reading of the highest pressure. You need a basic gauge without the pressure release valve.
Blocking the WUR inlet will raise control pressure to ~equal system pressure, essentially leaning the fuel mix.
Question: after the engine fails to start (after a few start attempts); does the exhaust tail pipe smell like gasoline?
Tbd
Member
Good to know that the gauge is not the right type, I was thinking there was something odd in the readings, hence the title of this thread.
As to blocking the WUR inlet raising the control pressure - you are right. I was thinking backwards. And then given the fact that closing the valve got the engine to run, and when I previously measured control pressure as very high and then was able to start the engine with no problem, it seems consistent but I don't understand what could be causing the engine to die right as the cold start injector is closing.
No, the exhaust tail pipe did not smell like gasoline (I tried starting it again in the 'stock' configuration after reading your post, and checked the tailpipe just to make sure). I don't think that it was flooding, when I start it it lights up and runs very easily, but only for the four or so seconds. Sometimes it dies quietly, sometimes it gives a 'lean' cough and sputters a bit.
Last edited by dreiermann; 02-02-2017 at 09:35 PM.
Member
I replaced the WUR with one from a "running when removed" 1983 engine. No change in the symptoms at all.
This, combined with the nearly-pristine condition of the inside of the one I removed, lead me to think that it is not the WUR at all.
I just don't know where to go from here (besides ripping out the K-jet and going to carbs or MegaSquirt). Any ideas would be appreciated. Thanks!
Member
You should check for vacuum leaks under the hood, and I'll say again:
If the 'primary' fuel filter (next to the fuel pump) is very dirty (happens sometimes with 'winter' fuel), the filter element may have a tear in it, making a mess of the fuel system. I suggest getting a new primary fuel filter and then later continue with your t-shooting efforts. Also drain the fuel filter 'inlet' to a clean container to get an idea of the fuel tank(s) condition...
This is also very important:
While you're down there; if the 3 pieces of fuel hose on the suction side of the primary fuel pump are the original cloth braided hoses; they need to be replaced, because sucking air bubbles and possibly seeping fuel.
Last edited by epmedia; 02-05-2017 at 12:33 AM.
Tbd
Member
Epmedia,
I had planned to replace all the vent lines this winter, but had hoped to get the non-start issue resolved first. I suppose that I will just go ahead and drop the tanks now, and also replace any flexible pressure hoses that I find. Does it make sense to replace the accumulator while I am doing all that? I have no indication of losing rest pressure, but from the looks of it, the accumulator is original and I don't know if the diaphragm of those things will last more than 40 years in fuel. As for the fuel filter, I put on a new Mahle filter last summer, it probably has less than 1,000 miles on it. I opened up the old one and it did not look that dirty, either. So if the fuel filter is bad, it was bad when it left Mahle. But the point is moot because with all the other work I will be doing, it's getting a new filter anyway.
Thinking about vacuum leaks, I had discounted that possibility because it ran so well for the four seconds prior to dying - not like times when I tried to start it with a known vacuum leak. Could it be that the cold start injector is just enough to 'cover' the extra air so that it runs smooth for that time, and then immediately dies when the extra fuel is stopped? One of my other winter projects was to pull/test/clean the fuel injectors, and replace the seals around them as well as the intake manifold gaskets - if it is a vacuum leak then hopefully that work will take care of the issue, or at least I will be able to see some other issue when the intake manifold is off.
Back to the fuel and vent hoses - local parts stores do not have metric sizes, so I was planning to order from Pelican Parts - I would guess that the hoses they carry use the more 'modern' compounds that don't deteriorate as quickly as the originals (and I am talking primarily about the vent hoses), if anyone knows differently please let me know.
Thanks so much!
Member
dreiermann - As an FYI I just ordered all of the metric vent lines from FCP Euro. They carry CRP (Continental) hose by the meter in the 3 sizes needed to replace all the vent lines.
BMW Fuel Hose - CRP 13311272750 6x12mm 1 $8.99
BMW Fuel Hose - CRP 16121177553 14x20mm 1 $17.99
BMW Fuel Hose - CRP 16121176440 12x18mm 1 $8.74
Nothing wrong with Pelican - great folks - just another data point.
MJ
Member
I cannot accurately respond to your questions regarding the accumulator and system rest pressure because of the test gauge you were using (having pressure release valve).
The 3 pieces of fuel hose on the suction side of the external(primary) fuel pump connect to the metal "Y" fitting next to the external fuel pump. The fuel tank(s) do not have to be dropped to replace them(replace them if original).
Never discount vacuum leaks, and yes - the cold start injector could help the engine idle 'sweet' for a few seconds.
Have you cleaned and tightened the fuel pump(s) fuse and holders, yet?
There is so much to still check, and the gauge you were using 'sort of' makes previous tests invalid.
Tbd
Member
Regarding the accumulator, even if it tests good now my question is whether a 40-year old accumulator can be expected to last another 10 years. If not, I will replace it now along with the other work that I am doing.
For the fuel tanks, it is correct that I don't need to drop them to replace the lines at the fuel pump, but I will need to drop them to replace the vent lines (which I suspect as the source of gas smell when the tank is more than half full and/or after hard(ish) cornering. A new fuel gauge sender o-ring will also help.
For the fuel pump electric, I have not checked that yet but even with the non-pressure-release gauge, the test of system pressure should be valid. The biggest possibility of change in system pressure (when I am done with the planned work) will be from removing the secondary external pump (which appears to have been there for a very long time, and may have been added as someones interpretation of the service bulletin that called for an additional internal pump.
For vacuum leaks, as part of my planned winter work I just removed the intake manifold to access the fuel injectors, which I have also removed and will test. The seals in those were like rocks, although the injectors themselves could rotate easily in their ports. So if the vacuum situation is better when I am done, it will probably be due to the new seals at the injectors.
I don't like to do a 'shotgun fix', but there are so many things that I had planned to do as preventative maintenance anyway, I might as well go through them all and have a good baseline to start with. Still, I would like to know what the one thing is that changed/failed to cause the non-start issue.
It will be a few weeks before I get through all of this, but I will update when I can test again (with the right gauge this time).
Thanks so much for all the info and advice!
Member
Are you saying that you have two external fuel pumps? There's been atleast 2 other members here claiming the same for their '77s. The two '78s I've had/have were original with just the one external pump. There was a recall to install the in-tank pump to 77-79 years, which neither of mine got retrofitted (and I'm glad of this).
My accumulator still works, but if I had the $, I'd probably replace it too, and keep the old as a spare. Get a new one whilst still available.
Be sure to get the proper injector o-rings. The 1.8 and 2.0 engines have different injector seal designs.
Tbd
Member
I may be one of the members you are thinking about, with the two external pumps. I might have even started the thread that was discussing it (last summer?), because I was trying to determine if it was original/necessary.
Yes, the seals I got are supposed to be for a 2.0, I know that the 1.8 had a different manifold and from what I can tell based on part numbers, they had different injectors too. Which is unfortunate for me because having broken a 2.0 injector while removing it, I cannot simply pull a replacement from the 1.8 under a tarp in my backyard.
I think that I will go ahead and replace the accumulator. If I wait, I know that it will fail right after the remaining stock disappears from US warehouse shelves. Or after the Porsche K-Jet owners discover that it fits a 911 (disclaimer - I have no idea if it does) and the prices go through the roof (like with the WURs).
Member
Check the rockauto for the parts you need, very decent prices.
Tbd
Member
Yes, RockAuto is a great place to shop, and their prices can't be beat!
Some updates: I removed the driver-side fuel tank and looked inside. It doesn't look too bad, although there is some rust. Not loose rust, it just has the look of red primer in part of the tank (toward the bottom). I am debating whether I should try to remove that rust or just consider it to be benign. Any suggestions? The fuel filter looked very clean and shiny at the inlet and outlet, but I have not cut it open.
Secondary fuel pump - with the carrier holding the main pump, accumulator, and filter removed, I was able to get a clearer picture (attached) of the secondary pump. Before, I thought that it looked like someone had just found a shortcut to installing the in-tank-pump for the update, but now I can see that the mounting bracket looks like it was a factory piece. The same isolator mountings, and it is mounted on a platform that is held on by the differential bolts.
The replacement parts are arriving from many sources, I did use FCP Euro for the fuel lines and the intake manifold gaskets, and they are fantastic to work with, I will shop there again. Hopefully this weekend I will finish cleaning/painting the parts to be re-used and can then start running the new lines and putting everything back together.
Member
Getting frustrated. Here is where I am at:
Replaced all fuel lines and vent lines from the engine compartment back. New fuel pump, new accumulator, new fuel filter. In replacing those, I removed the secondary external pump. Removed intake to get at injectors, soaked them in Gumout overnight and back-flowed more Gumout through them with compressed air, then tested for spray pattern which looked good. Soaked the tip of the cold start valve in Gumout overnight. Permanently plugged all unused gaskets in the intake manifold. Many new vacuum lines throughout. All new gaskets on the intake manifold and new seals on the injectors. WUR flushed recently. Tested cold start valve, it is flowing. Tested auxiliary air valve, it is working. Tested cold control pressure without the bleeder on the gauge - still high (65psi).
Results: Same symptom as before - engine runs for a few seconds then dies.
I am worried that it there is a problem with the fuel distributor. Or could something be interrupting the ignition after a few seconds of running, on a consistent basis? I am running out of ideas, any help is appreciated.
Thanks!
Member
In your first post, you said that you ran the WUR outlet into a gas-can and had 68 psi cold control pressure. This tells me that the fuel dist is not what's causing high 'cold control' pressure (Ie: an obstruction in the fuel dist to the tank return). Or maybe this was because of the gauge with the pressure release button causing incorrect pressure readings. Maybe you should try that test again.
What is the fuel 'system' pressure now?
Last edited by epmedia; 04-24-2017 at 03:08 AM.
Tbd
Member
When I tested right before my last post, system pressure was the same as cold control pressure = 65 psi. After posting, I thought that maybe there was some air in the lines to the injectors (which had been out) so I would try starting until the air got out. It worked! And I started the car normally several times after that over the course of a couple of days. It ran rough, but it ran. Today I checked the valve clearance as the first step in a full tune-up, but when i went to warm up the car to check the timing, it would not start. Several times it ran for a few seconds then died, but mostly it would just sound like it was about to catch, then didn't. I tried running the WUR to a gas can, that did not help. I tested cold control/system pressures again, and was shocked to see over 100 psi! This has me worried. Is the pressure regulator (assuming that's what is causing the high pressures) rebuildable without opening up the entire fuel distributor?
Member
When the cold control pressure was 100 psi, was this with the WUR outlet going to your gas can?
Either way; we all know that 100 psi is too high and this tells me the fuel pressure regulator is either stuck, or there's an obstruction in the fuel return (either in fuel dist or pipe/hose). I remember you mentioned replacing hoses around the fuel tanks - make sure that rubber section of return hose (under the tank access cover) is not kinked.
Yes, the fuel pressure regulator is accessed from the outside of the fuel dist. Be very careful not to loose or drop any parts.
fuel pressure regulator
Prim-press-regulator-1.jpg
Tbd
Member
That was good thinking about the return line getting squeezed under the access plate - that plate was one thing that I had re-installed between the tests. It gave me a few minutes of hope, but unfortunately that was not the culprit - I opened the plate and all the hoses were fine, checked the pressure and got the same results. Still, I will remove the return connection in the engine bay and blow air through it just to be sure.
After that, my plan of attack is to remove/inspect/repair the pressure regulator. If I don't find any smoking gun, I will open up the fuel distributor.
What is really killing me is the intermittent nature of the problem. Until I can find something that is visibly wrong, I won't be sure that it is really fixed.
Member
OK, in an attempt to be logical, I decided that rather than just blow air through the line to check for clogs, I would run a line directly from the fuel distributor return into a gas can, and check the system pressure. Guess what? It was only 60 psi. Clogged or pinched line? Well, get this - I re-connected the line to the tank and measured again - still 60 psi!
So, moving on up the line to look for the intermittent problem, I removed the fuel pressure regulator. It looks just like the picture that Epmedia attached (above), except for the fact that there is no o-ring on the tip. Now the question is, where did the old o-ring go? I know that I didn't drop it when removing the pressure regulator because I had a sheet of white paper underneath the opening when I took the regulator out. Could it have gotten sucked farther into the fuel distributor? I can't imagine that it dissolved completely, the larger o-ring (closer to the outside) is still in good shape. I removed the return line and the line to the WUR to see if I could see the o-ring from there, but I could not.
So now I appear to have found a smoking gun, but the bullet is still on the loose. Again, any suggestions are appreciated. Thanks!
Member
Well, I'd imagine the o-ring piece(s) are probably blocking the passage to the fuel return. I wish I knew how all the passages were arranged. You may even see the o-ring piece(s), deep in that pressure regulator hole, hopefully it's still in one piece!
I'm hoping someone here has a spare o-ring for you. There are supposedly 2 different sizes of the o-ring. Can you post a pic of the fuel pressure regulator (the 'piston' part, where the small o-ring fits)? Or just use this pic for reference?
*The o-ring material is special, cannot use plain o-rings from the local auto store. The material may be Viton for the pressure regulator, but there was a discussion about this awhile back about a different material that held up better for the pressure regulator, I forget what that material is. (it holds up to the same fuels/chemicals as viton, but is more rugged than viton).
From post #25 on this thread:
https://www.bimmerforums.com/forum/s...Rebuild-How-To
Last edited by epmedia; 04-29-2017 at 04:50 AM.
Tbd
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