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Thread: 1982 e21 320i fuel injection issues, making me crazy!

  1. #1
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    1982 e21 320i fuel injection issues, making me crazy!

    Hello, new to the forum, but not new to working on cars. First time working on CIS K-jet fuel injection though. My son was driving his excellent running 1982 320i and it died. He described it as if someone turned the motor off. I assumed that it was electrical, based on his description so I replaced the ignition coil. Still did not attempt to fire so I verified that he is getting spark to the plugs. Started googling other issues for this car and stumbled across this forum. Did several searches and didn't find what I was looking for. This one looked frustrating though! https://www.bimmerforums.com/forum/s...fuel+injection

    Here is what I have done so far, aside from the new coil.
    • Replaced fuel pump relay.
    • Replaced exterior fuel pump
    • Replaced Fuel filter
    • Sprayed starting fluid into the air filter intake assembly to verify that it was a fuel delivery issue. The engine started for a second, but quickly died.
    • Jumpered the fuel pump relay plug to test.
      • Noted a buzzing noise that sounds like its coming from the FI distribution block.
      • Pulled the main line going into the distribution block. There is fuel and pressure up to that line. It sprayed all over when I cracked the banjo connector open.
      • Pulled an injector line off of the distribution block. I could see fuel in the hole, but no pressure.
      • After reading some more, I realized that I needed to pull the filter assembly out so I could access the air metering disk from inside. Some fuel came out when I pressed the up on the plate, but not a lot.
      • Also pulled the plug out of the front of the distribution block with the allen screw in the middle. I think I read in the forum that I attached above that the allen head is the base mixture screw. It was somewhat difficult to get out once the threads were no longer engaged. Also managed to get the little metal plunger out. Put it back together, but have not tried to start the car again.
      • Through out most of these tests, I have been pulling a couple injectors to see if I am getting any fuel and I am not. Even when I was able to get my hand in the CIS to push up on the plate, I did not get fuel out of the injectors. Tried before and after pulling the banjo connector off of a couple of the injector lines and did have fuel there.

    Things I have not tried.
    • Fuel pressure testing with a gauge. I will need to pick a tester up tomorrow.
    • Replace the internal fuel pump. Hoping that is not the issue. Sounds like a pain
    • Remove the CIS to throttle body boot. Not sure how to accomplish this without taking the intake manifold off,


    Sorry for being so wordy, but I thought it would help to get what has been done posted. Any help at all would be fantastic. Are there other things I need to check?

  2. #2
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    Dying like someone turned it off (rather than stumbling to death) sounds electrical to me rather than fuel-related.

    I would try testing and/or replacing the ignition module. They look like this: https://www.autohausaz.com/pn/113511...xoCUOcQAvD_BwE

    I don't have a late model car, but I believe it's located on the drivers side inner fender between windshield and strut top.

    Unfortunately I can't seem to find any diagnostic procedure for this guy..
    Last edited by cgifool; 08-02-2018 at 03:22 PM.

  3. #3
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    "Jumpered the fuel pump relay plug to test. Noted a buzzing noise that sounds like its coming from the FI distribution block. "

    This is normal its the Frequency Modulation Valve attached to the back of the Fuel Distributor and is an fuel injector enrichment device, its runs constantly when the Fuel Pump Relay socket is jumpered-if it was not buzzing that would be a problem, no fuel to injectors though until the sensor plate is raised.

    "I have been pulling a couple injectors to see if I am getting any fuel and I am not. Even when I was able to get my hand in the CIS to push up on the plate, I did not get fuel out of the injectors."

    With the fuel injectors in the cylinder head, fuel pump socket jumpered, lifting the sensor plate(with air filter box out) by hand--you should hear a squeal of the injectors--high pitch noise fuel going thru the injectors 1 thru 4.

    "Also pulled the plug out of the front of the distribution block with the allen screw in the middle. I think I read in the forum that I attached above that the allen head is the base mixture screw. It was somewhat difficult to get out once the threads were no longer engaged. Also managed to get the little metal plunger out. Put it back together, but have not tried to start the car again."

    That item pulled out takes a 16 mm socket and is the Fuel Distributor Pressure relief valve and has two o ring's on it.. How do they look ? No fuel pressure[fuel] to injectors could be the pressure relief valve small o ring on the plunger is cracked or broken--thus no fuel pressure build up to send to the injectors--dump straight back to the fuel tank. 44 psi is needed in fuel pressure at the fuel injectors to get them to open and spray fuel into the intake manifold ports 1 thru 4.
    Picture below



    Read FAQ's here on the fuel section, CIS testing tests more than fuel pump pressure in the fuel distributor, tests the Warm Up Regulator as well which is a big part of CIS Fuel System. If the warm up regulator went kaput this would cause a fuel issue as well. A CIS test kit is referenced there, I have that one and another complete new kit as my backup to do all the tests, shop around may find a better price. You and your son are on the learning curve,, enjoy.

    Randy
    Last edited by 320iAman; 08-02-2018 at 04:14 PM.

  4. #4
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    Great points Randy. Fuel may be getting to the distributor, then returning right to the tank, without building pressure in the fuel distributor.

    When the OP said this, "Even when I was able to get my hand in the CIS to push up on the plate" i think he must have meant lift the plate, because lifting the plate measures airflow, and increases fuel flow.

    Randy has a fuel distributor rebuild thread, which these tend to need to have done due to their advanced age, and O-rings going bad, etc.

  5. #5
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    '81 E21 320i / '90 E30 325i / '̶9̶2̶ ̶E̶3̶4̶ ̶5̶2̶5̶i̶t (sold) / '15 Toyota XW30 / '̶̶8̶0̶ ̶E̶2̶1̶ ̶3̶2̶0̶i̶A̶ (sold)

  6. #6
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    Quote Originally Posted by cgifool View Post
    Dying like someone turned it off (rather than stumbling to death) sounds electrical to me rather than fuel-related.

    I would try testing and/or replacing the ignition module. They look like this: https://www.autohausaz.com/pn/113511...xoCUOcQAvD_BwE

    I don't have a late model car, but I believe it's located on the drivers side inner fender between windshield and strut top.

    Unfortunately I can't seem to find any diagnostic procedure for this guy..
    Correct. That is what I thought also, so that is why changed out the coil. As I stated here -> "He described it as if someone turned the motor off. I assumed that it was electrical, based on his description so I replaced the ignition coil. Still did not attempt to fire so I verified that he is getting spark to the plugs."

    Also through out the rest of the initial post, I talk about how I am not getting fuel out of the injectors.

  7. #7
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    Thanks for the replies. Here are some answers.

    "With the fuel injectors in the cylinder head, fuel pump socket jumpered, lifting the sensor plate(with air filter box out) by hand--you should hear a squeal of the injectors--high pitch noise fuel going thru the injectors 1 thru 4."
    - I lifted the sensor plate with the fuel pump jumper in place and ignition key on, still no squeeling or fuel coming out of the injectors.

    "
    That item pulled out takes a 16 mm socket and is the Fuel Distributor Pressure relief valve and has two o ring's on it.. How do they look ? No fuel pressure[fuel] to injectors could be the pressure relief valve small o ring on the plunger is cracked or broken--thus no fuel pressure build up to send to the injectors--dump straight back to the fuel tank. 44 psi is needed in fuel pressure at the fuel injectors to get them to open and spray fuel into the intake manifold ports 1 thru 4."
    - The orings looked like they were in OK shape to me. I might pull them out again just to take a second look, not that I sort of know what its for.

    Having a hard time getting my hands on a fuel system tester locally. Thinking about building one based on these instructions -
    http://mikegabriel.ca/vw/badhabitrabbit/fpressure.html
    I have a fuel pressure gauge, just need to find the fittings, which souds like the hard part.

  8. #8
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    Do you have voltage across the two receiving terminals of the fuel pump relay when you jump it? Always worth testing. And unless I'm mistaken your car would have a secondary fuel pump as well, did you inspect that one? Probably wouldn't stop fuel flow all the way though
    -John

  9. #9
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    Quote Originally Posted by Somjuan View Post
    Do you have voltage across the two receiving terminals of the fuel pump relay when you jump it? Always worth testing. And unless I'm mistaken your car would have a secondary fuel pump as well, did you inspect that one? Probably wouldn't stop fuel flow all the way though
    I didn't check it with a volt meter, but it does cause the distribution block to buzz. One of the other responders said that its normal if there is power going to it. I have also tested for voltage at the external pump, and I have power there as well. As far as the second pump in the tank, I have not checked that, but I do have fuel flow up to the point of the distribution block, just not past it.

  10. #10
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    Maybe some of the rest of you missed this, but it seems there is fuel flow to the fuel distributor.

    The OP said this "Pulled the main line going into the distribution block. There is fuel and pressure up to that line. It sprayed all over when I cracked the banjo connector open."

    So it seems like we can eliminate the fuel pumps not working.

    So I'm thinking it's the fuel distributor not functioning somehow. Like Randy was saying. Or maybe that piston thing in the very center, that the airflow metering plate causes to move, but it's stuck and not moving.

    You see the airflow plate #9 in the diagram, causes the piston in the center of the fuel distributor #5 to move when lifted.





    - - - Updated - - -



    - - - Updated - - -

    The last picture is from Randy's rebuild, and shows all the O-rings in this thing.

  11. #11
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    Thanks for all of the fantastic support so far. I read through all of those Bosch PDFs. Very interesting! One of them was written by Robert Bosch! This might kind of a stupid question, but on top of the fuel distributor, where the main fuel line comes in and the return line goes out, there are arrows. The one on the from points inward toward the unit and one on the side points outward away from the unit. Assuming that the one on the front is the main fuel line feeding the block and the one on the side is the return line? I can't seem to find a schematic that shows which line is for what. The injector and WUR lines are obvious, but the main inlet and outlet aren't so much.

    The main reason I am asking is, when I cracked the banjo connector open in the front, there was pressure and it sprayed everywhere. When I cracked the banjo connector open on the side, a little bit of fuel dribbled out, but not much and there definetly wasn't any pressure to speak of. I opened both lines twice, once with the key on and jumpered pump connections, and once without the key on. I had pressure on the front (inlet?) both times and with the key on, the fuel kept coming. Both times I opened the connector on the side (outlet?), there wasn't any pressure.

    I also mentioned earlier that I pulled the Fuel Distributor Pressure relief valve out and inspected the O-rings and piston. While it was out, I turned the ignition on and fuel came gushing out of that port. where the relief valve was at.

    Not sure if any of this information is useful to anyone in regard to helping me diagnose the issue, but I thought it was notable. Let me know if that sheds any light on the subject.

  12. #12
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    Quote Originally Posted by okieflats View Post
    Maybe some of the rest of you missed this, but it seems there is fuel flow to the fuel distributor.

    The OP said this "Pulled the main line going into the distribution block. There is fuel and pressure up to that line. It sprayed all over when I cracked the banjo connector open."

    So it seems like we can eliminate the fuel pumps not working.

    So I'm thinking it's the fuel distributor not functioning somehow. Like Randy was saying. Or maybe that piston thing in the very center, that the airflow metering plate causes to move, but it's stuck and not moving.
    This is kind of what I am afraid of. Seems like getting the CIS unit out from under the intake manifold and throttle body is going to be a royal pain in the @$$. I tried to remove the boot between the CIS and throttle body, but I was afraid I would rip or crack it. Also looked for some information on that as well. Not sure if anyone has any information on removing the boot and CIS?

  13. #13
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    bmwandsons - have the 3 pieces of 'cloth braided' fuel hose on the suction side of the external fuel pump ever been replaced? if not, they are sucking air bubbles and seeping some fuel. All 3 pieces of hose are connected to the metal "Y" fitting next to the external pump, 2 hose sizes..

    You also want to clean the fuel pump fuse and it's holders, make sure the holders hold the fuse tightly too. Try to only use the copper/brass fuses. the silver-color fuses corrode too fast.

    The (post #9) little o-ring, bottom-right of the picture is the fuel pressure regulator o-ring that gets worn-out. When it wears-out, the fuel 'system' and 'rest' pressures will fail.
    ---
    If you still have the old fuel pump 'check-valve', this check-valve can be gutted (remove the ball and spring), and used as a fitting for testing the fuel 'system' pressure and 'rest' pressure at the inlet of the fuel distributor. Only need some spare hose and clamps if your gauge can fit to the spare piece of hose. Use fuel injection hose - the fuel system is capable of well-above 100psi! See the diy/faq thread for fuel pressure specs and be safe with fuel!

    For testing purposes only!
    (click to enlarge)
    fuelsystester.jpg
    Tbd

  14. #14
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    Thats correct Robert the fuel pressure regulator has two o-rings small one on the plunger and the larger one, the larger one is called Warm Up Regulator O-Ring-when it breaks or cracks rest pressure will not hold, when the small one gets flat or is cracked and so forth fuel pressure in the fuel distributor drops down.. Rest Pressure is the final test in doing the CIS Testing with a CIS gauge and hose hookups. --> System pressure, Cold Control Pressure, Warm Control Pressure and Rest Pressure.

    Randy
    Last edited by 320iAman; 08-04-2018 at 02:13 PM.

  15. #15
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    You can pull the FD off the air meter without too much fuss, it's the 3 flathead screws on top of the thing between the injector lines. Just make sure you use the right size, they're quite tight and working with the weird angles you need to get the back two off it's easy to mangle the heads.

  16. #16
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    Quote Originally Posted by epmedia View Post
    bmwandsons - have the 3 pieces of 'cloth braided' fuel hose on the suction side of the external fuel pump ever been replaced? if not, they are sucking air bubbles and seeping some fuel. All 3 pieces of hose are connected to the metal "Y" fitting next to the external pump, 2 hose sizes..

    You also want to clean the fuel pump fuse and it's holders, make sure the holders hold the fuse tightly too. Try to only use the copper/brass fuses. the silver-color fuses corrode too fast.

    The (post #9) little o-ring, bottom-right of the picture is the fuel pressure regulator o-ring that gets worn-out. When it wears-out, the fuel 'system' and 'rest' pressures will fail.
    ---
    If you still have the old fuel pump 'check-valve', this check-valve can be gutted (remove the ball and spring), and used as a fitting for testing the fuel 'system' pressure and 'rest' pressure at the inlet of the fuel distributor. Only need some spare hose and clamps if your gauge can fit to the spare piece of hose. Use fuel injection hose - the fuel system is capable of well-above 100psi! See the diy/faq thread for fuel pressure specs and be safe with fuel!

    For testing purposes only!
    (click to enlarge)
    fuelsystester.jpg
    So this may be a big part of my issue. I pulled the main fuel feed line off again yesterday and realized that the fuel pressure that I thought I had there is mostly air pressure with some fuel mixed in. I pulled that line completely off and put it in a bottle, turned the key on and it was sporadically squirting fuel, not a consistent stream. It was also making gurgling noises like it was sucking air. When I climbed under the car and had my son turn the key on, I could see some fuel spray out of one of the hoses by the external fuel pump. Unfortunately, I won't be able to work on the car again until Thursday, Wednesday evening at the earliest.

    I did end up ordering a CIS fuel pressure test kit before I discovered the hose leaks, but I think I will just keep it in case we have other issues down the road. I am almost positive that once I correct the issues with the leaking fuel lines, I will have enough pressure to get the injector lines pumped up and delivering again. I will let everyone know if it works next week... hopefully.

  17. #17
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    Good to hear,, problems with cars is usually a process of elimination to find the solution, test and figure out whats working good and whats left is where the problem is that needs repair. You'll need the CIS test kit sooner or later anyway, good move to have it. I test the CIS system once a year.

    Randy
    Last edited by 320iAman; 08-04-2018 at 08:45 PM.

  18. #18
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    So to wrap this up, I changed out the 2 fuel lines that are different sizes that lead into the "T" that is right off of the fuel pump and leads into the main line going to the engine. Let the pumps run for a minute or so with the pump relay jumpered, and Viola! I have pressure at the injectors! Car fired right up, better than it ever has. Put the pump relay back in, and everything else back together. My son was taking off for a test drive before I could even get the hood shut. Not really, he waited patiently as I wrapped it all up, but the point is that he is stoked to have his freedom again. Looking back on the whole thing, I think I must have cracked the old brittle fuel line when I was changing out the pump. Pretty sure the original pump was bad anyway. Thanks again for all the help!

  19. #19
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    Quote Originally Posted by bmwandsons View Post
    So to wrap this up, I changed out the 2 fuel lines that are different sizes that lead into the "T" that is right off of the fuel pump and leads into the main line going to the engine. Let the pumps run for a minute or so with the pump relay jumpered, and Viola! I have pressure at the injectors! Car fired right up, better than it ever has. Put the pump relay back in, and everything else back together. My son was taking off for a test drive before I could even get the hood shut. Not really, he waited patiently as I wrapped it all up, but the point is that he is stoked to have his freedom again. Looking back on the whole thing, I think I must have cracked the old brittle fuel line when I was changing out the pump. Pretty sure the original pump was bad anyway. Thanks again for all the help!
    Great to hear and thanks for reporting back.
    Tbd

  20. #20
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    I still wonder if that's not my issue now mine will start and run hit the throttle it dies. Than crank and crank it will run than die. Once it idles long enough it will stay running but it seems to idle too low in the 600 to 700 rpm range. But if it sets for a few hours issue comes back. Here is a question does the older bmws do the same as vw if u pull the oil dip stick or open oil cap and dies. Is that normal or is Pcv valve bad.

  21. #21
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    Quote Originally Posted by Shelby7169 View Post
    Here is a question does the older bmws do the same as vw if u pull the oil dip stick or open oil cap and dies. Is that normal or is Pcv valve bad.
    My M10 will die if I pull out the dipstick. Probably same if pull the oil cap. Pretty sure that is a good sign as it no longer has vacuum.
    '81 E21 320i / '90 E30 325i / '̶9̶2̶ ̶E̶3̶4̶ ̶5̶2̶5̶i̶t (sold) / '15 Toyota XW30 / '̶̶8̶0̶ ̶E̶2̶1̶ ̶3̶2̶0̶i̶A̶ (sold)

  22. #22
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    Just making sure I know if you do it on a vw it was a bad pcv valve on newer ones anyway

  23. #23
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    Quote Originally Posted by Shelby7169 View Post
    I still wonder if that's not my issue now mine will start and run hit the throttle it dies. Than crank and crank it will run than die. Once it idles long enough it will stay running but it seems to idle too low in the 600 to 700 rpm range. But if it sets for a few hours issue comes back. Here is a question does the older bmws do the same as vw if u pull the oil dip stick or open oil cap and dies. Is that normal or is Pcv valve bad.
    If those previously mentioned hoses have never been replaced (cloth braided, on the pump suction side), it probably is the problem.
    Tbd

  24. #24
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    No car sat for 6 years transfer pump In tank ground wire rusted off replaced both of them need to do fuel filters yet but I bet the plungers are weak takes awhile to build enough pressure to give throttle response

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