Adapted from BigBisonT over at bimmerforums.com.
Original can be found at http://forums.bimmerforums.com/forum/sho...hlight=m20
In my own little adventure, I gathered a blend of info attained from various no-start threads and plain ol’ Bentley troubleshooting (member credits for thread info have been tagged when applicable. Apologies to anyone who feels slighted, but I don’t remember everywhere I read everything!). As I have an m60b30, there is a slight m60 lean to most topics, but hopefully the core info is still useful to most.
* Many tests require a multi-meter. Most likely have them, but Noobs; if you own a car that is not under warranty or you own a home, you really should have one of these. They are $20-$30 and can be purchased from auto part stores, home improvement stores, and even Walmart. It’s not that complicated and it WILL save you time, frustration, and BIG MONEY in the long run. There is nothing worse than spending money to replace a part that wasn’t actually the problem.
*Stomp tests or proper fault code readouts should be taken to save yourself some trouble when possible. If there is a “Check Engine Light”, then there is something stored that you should probably know about! (** if you have already tried to jumper your fuel pump, ignore the 1261 code! That was most likely tripped by the jumper, so don’t sweat it.)
“THE” NO-START CAUSES (bold is most common)
1. Fuel not reaching engine (empty tank?, bad fuel pump, injectors), Bentley section 160,130
2. No Spark/voltage to plugs (Battery, plugs, coils, relays, wires/sensors), Bentley section 120
3. Other (engine flooding, Air intake, and random things). Not particularly likely…but crazier things have happened!
*the biggest no-brainer of all is if you get cranking, try jumpstarting your battery first to eliminate the prospect of a dead battery. Bring battery to auto parts store to test if still unsure. Once you know that’s not it, then proceed…
-1. FUEL ISSUES:
* Many fuel pump tests are made easier with a “jumper” in place of the relay (located in E box right side) so that engine cranking is not necessary in order to run pump. You can build a nice one that includes a fuse for roughly $9. At auto parts store, find spade terminal ends ($3), an “in-line fuse holder” (which includes wires already attached to fuse slot, $3) and then a pack of 15A fuses ($3). Crimp the ends onto the ready-made wire/fuse combo and you have instant and safe jumper. Jumper slots should correspond to terminal slots 30 & 87 from the Fuel Relay.
*Access to fuel pump/sending unit is achieved by removing trunk carpet and unscrewing the obvious egg shaped panel (5 screws) on the right. The fuel sending unit really just measures ‘full/empty’, but it’s the middle man for power to the pump, so keep in mind the pump is under it. Removal of the pump is not necessary to check for voltage at the harness connections or even to test for pressure/flow. You only need to start pulling things apart if you decide to replace the pump.
-Fuel pump fuse: Should ALWAYS be stop #1. The fuel pump fuse is #23 in the engine bay fuse box. If its blown, or looks even slightly off, try swapping it.
-Check for power at the fuel pump. Details can be found in Bentley in section 160-6, but the gist of it is running the pump (via jumper) and listening if you can hear it and/or checking for voltage using your multi-meter (terminal 4/neg & 5/pos) at the harness connection. Power to the pump, but no pump activity when reconnected likely means shot pump (replace). If no power is supplied and/or jumpering the fuel relay doesn’t at least provide power, skip straight to trouble-shooting relays.
- Check for pressure/flow (if pump has power, and activates)
a. Pressure: Unhook the supply line IN at the RAIL in the engine bay and install a “T” with a fuel pressure gauge (nice kits are often available for rent at auto parts stores. They have expensive deposits, but you should get 100% of you money back upon return). Operate pump (via jumper) and check for around 51psi in M60/M50 and 44psi in M20/M30. Too high means blockages/kinks somewhere or the fuel pressure regulator is shot; too low means pump is shot or flow obstructed between pump and rail (clogged fuel filter most common culprit).
* Despite easier access to sending unit/pump in trunk, all pressure/flow tests should be done in engine bay because pressure from the pump doesn’t necessarily tell you anything about gas actually reaching the injectors (ask me how I know!...)
b. Flow: Disconnect RETURN line from fuel RAIL in engine bay and attach a length of hose to direct gas into a safe container from the rail. Operate pump with the jumper and you should get a nice stream filling approx a Quart in ~30 seconds. If you get a lot less, your pump may be shot (replace). “530IT” says he discovered during this test that a significant amount of what was pumping was actually water that somehow got into the tank, resulting in his no-start.
*you may want to try and blow air through the return line, pressure regulator, and fuel filters. Clogs or kinks can def be a problem. Never use compressed air over 87psi though! It could cause damage to lines/parts.
-Fuel Relay (locations vary): If the fuel pump gets power when you ‘jumper’ the terminal, but not when the relay alone is installed (and cranking with key), then its pretty clear the fuel relay needs to be replaced. If you get no power to pump either way, double check voltage to sockets with multi-meter, then see main relay.
-Main Relay: If you can get one cheap, I say swap it right away. Bentley section 130-6 has details, but with ignition OFF, you need to pull it and check for voltage at terminals 30 & 86. If that’s fine, plug in the relay and turn ignition ON. Then you need to get access under it (accomplished via two 10mm bolts that allow the entire relay row to come up out of box, careful not to disconnect wires though). From the bottom, check for ground at the brown wire (terminal 31). If there is ground, you’re good, if not the ECM signal is missing. If fine, check voltage at both “87” terminals to see if the relay is “energized and functioning”. If Power is at fuel pump, and relays are looking good, then it could be an ignition system issue.
-2. “Spark” IGNITION SYSTEMS:
- Check for spark: Bentley outlines easier ways in other engines, but for my m60b30 I had to pull a coil, pull a plug, pop plug into coil (still-connected harness), and ground the plug to engine bay (I used a heavy copper wire that I first wrapped around the plug, then wrapped around the threaded stud, that normally secures coil. I bent the wire so that it held the coil/plug upright where it was easily visible from the driver seat), BUT BE CAREFUL. The shock could theoretically and LITERALLY KILL you). Crank the engine and if you see spark, then it’s not your coil, plugs, or starter. If you don’t see a spark…
- Check Plugs and coils: Fouled plugs are hard to test, so I just bought new ones. Bentley section 120-4 outlines other engines, but the following info was, again, for an m60. For coil issues, first check for voltage to the coil connector harness (terminal 15/pos, ground/neg). IF no power, then you found your problem and trace back the wires to the fuses and/or relays. If voltage is present, test the coil itself for an ohm reading on your multi-meter. This really is more for if it runs like crap. As “Sir Montalbon” pointed out, the odds of 8 simultaneous failing coils leading to a no start is unlikely. Still, it only takes a few minutes and its best to be sure. Terminal 1/neg & 15/pos should give you of 0.4-0.8. Out of range = replace coil.
- CHECK YOUR CPS!!!: The bad CPS (on front of engine, under air boot) is arguably the most common issue for no starts on m50 and m60 engines. Disconnect and test it’s resistance with your multi-meter (terminals 1 &2)
Per ‘93FIM5’ “(if) This is reading below ~510-540 ohms I would say replace your CPS, that was my issue. The DME doesn’t see the engine cranking so it doesn’t initialize the pump or fire the plugs.”
*the Bentley says a 1280 ohms +/-10% reading should be present in m60 and m50 engines, but the m50 CPS listing is generally acknowledge to be wrong. The 550 range is actually correct. People with m60s have claimed to have both 550ohms AND others claim 1250. It was reported by “dreiko” that Pelican parts told him the CPS itself has been superseded so many times that the originals may indeed have read 1280 and perhaps newer ones fall in line with 540ish. Considering the fact there are drastically differing styles, including ones with plastic vs. metal housings, this is not hard to imagine. In any case, most agree that a truly shot CPS will read an insane number (like ZERO or a number in the millions), so if you are in the neighborhood of either ‘spec’ number, you’re probably ok. If you’re stuck though, when in doubt- swap it out.
-Check the injectors: Pop cover off the injector wiring ducts (tabs) and hook voltmeter to each injector. Pulsed voltage should be present 0.3-1.0 VDC while engaging starter. If not, check the red/white wire (pos) for voltage to the injectors.
*Resistance of a pulled injector should be 10-20ohms (~16 @room temperature) on m50, m20, and m30 engines. M60 injector’s resistance is stated by the Bentley to be “not available from BMW”…
3. OTHER (air intake, flooding, oddball/extreme occurrences):
-A 50A fuse in the E-box: (US passenger side of engine bay) was the cause of “Sir Montalbon’s” no start issue. It seems to be a fuse relating to the air intake in some way. Someone else may clarify…
-Engine Flooded: “sfgearhead” solved his problem by discovering he had flooded cylinders. He suggests pulling the plugs (only if you confirm you do have spark) and letting the cylinders breath and dry out. Crank the engine after pulling the fuel fuse to clear out trapped fuel. Be sure all components previously tested are back in place when attempting restart for real.
*“mannd” elaborates with these excellent instructions: “The M60B30 motor, especially high mileage motors typically will have low compression. When they flood they can be nearly impossible to start, fuel saturates the intake and engine oil. When you first pulled out the spark plugs, are they wet? If they are and seeing that you have spark, try the following..........”
1. Remove and dry out all spark plugs
2. With spark plugs out and DME relay removed crank over motor to evacuate cylinders.
3. Refit plugs and DME relay
4. Remove fuel pump fuse
**Get a second person to help with the following. Ensure battery is charged fully and use a good battery charger as this process will be taxing on the starter and battery**
5. With the accelerator to the floor at all times, start cranking motor until started then ease off (this is clear flood mode).
6. When you hear the engine trying to start have the second person momentarily fit the fuse and remove.
7. Continue this process until the engine starts.
-MAF: A dirty or faulty MAF may cause some problems. Check for voltage with multi-meter. The problem here, as I see it, is the Bentley says a faulty MAF “usually” will still let the engine “start and run” (it just runs like crap). A full blown non-start is, in my opinion, unlikely to be caused by the MAF. But hey, if you’re out of ideas or if you discover you’re not getting power to the MAF at all, def trace back the wires/fuses for issues and/or try swapping it.
-Air Filter: Super blocked/clogged one would def prevent strong running, and possibly choke out an engine. Check it for buildup, clean/replace it and give her another go.
-The DME: 93FIM5 reports you need a pin-out of the DME to accomplish anything. I am clueless on this topic. If anyone can chime in that would be great.
-The EWS II (security system) can possibly disable a starter. For more info on that see Porschedude’s informative thread http://forums.bimmerforums.com/forum...ws+porschedude
“KyleCleveland” suggests trying alternate key. If the EWS isn’t getting the “it’s all good” signal from a faulty main key, perhaps the backup key is still intact. Always worth a shot.
- The starter. I have no experience here, but I suspect this should only be a suspicion of your truly getting zippy for output/cranking/power. If its trying to crank, it shouldn’t be the starter.
-Blown Motor. Do a compression test and find out. I suggest you do the compression test while doing the “evacuate” process of trouble shooting the flooded engine. You will already have the plugs out and DME & Fuel relays unhooked, so you may as well slap a compression gauge in there and see what’s up while you’re at it. Harbor freight sells the gauges cheap.
-Incorrect valve timing. Particularly older engines. Very eloborate process, see Bentley sec. 116
To those reading this for fun, please share your own stories about problems AND SOLUTIONS to your no-start issue (ESPECIALLY if not already covered)!.
To those reading out of necessity, best of luck!!!
Could one of the Admins made this a sticky please?
Original can be found at http://forums.bimmerforums.com/forum/sho...hlight=m20
In my own little adventure, I gathered a blend of info attained from various no-start threads and plain ol’ Bentley troubleshooting (member credits for thread info have been tagged when applicable. Apologies to anyone who feels slighted, but I don’t remember everywhere I read everything!). As I have an m60b30, there is a slight m60 lean to most topics, but hopefully the core info is still useful to most.
* Many tests require a multi-meter. Most likely have them, but Noobs; if you own a car that is not under warranty or you own a home, you really should have one of these. They are $20-$30 and can be purchased from auto part stores, home improvement stores, and even Walmart. It’s not that complicated and it WILL save you time, frustration, and BIG MONEY in the long run. There is nothing worse than spending money to replace a part that wasn’t actually the problem.
*Stomp tests or proper fault code readouts should be taken to save yourself some trouble when possible. If there is a “Check Engine Light”, then there is something stored that you should probably know about! (** if you have already tried to jumper your fuel pump, ignore the 1261 code! That was most likely tripped by the jumper, so don’t sweat it.)
“THE” NO-START CAUSES (bold is most common)
1. Fuel not reaching engine (empty tank?, bad fuel pump, injectors), Bentley section 160,130
2. No Spark/voltage to plugs (Battery, plugs, coils, relays, wires/sensors), Bentley section 120
3. Other (engine flooding, Air intake, and random things). Not particularly likely…but crazier things have happened!
*the biggest no-brainer of all is if you get cranking, try jumpstarting your battery first to eliminate the prospect of a dead battery. Bring battery to auto parts store to test if still unsure. Once you know that’s not it, then proceed…
-1. FUEL ISSUES:
* Many fuel pump tests are made easier with a “jumper” in place of the relay (located in E box right side) so that engine cranking is not necessary in order to run pump. You can build a nice one that includes a fuse for roughly $9. At auto parts store, find spade terminal ends ($3), an “in-line fuse holder” (which includes wires already attached to fuse slot, $3) and then a pack of 15A fuses ($3). Crimp the ends onto the ready-made wire/fuse combo and you have instant and safe jumper. Jumper slots should correspond to terminal slots 30 & 87 from the Fuel Relay.
*Access to fuel pump/sending unit is achieved by removing trunk carpet and unscrewing the obvious egg shaped panel (5 screws) on the right. The fuel sending unit really just measures ‘full/empty’, but it’s the middle man for power to the pump, so keep in mind the pump is under it. Removal of the pump is not necessary to check for voltage at the harness connections or even to test for pressure/flow. You only need to start pulling things apart if you decide to replace the pump.
-Fuel pump fuse: Should ALWAYS be stop #1. The fuel pump fuse is #23 in the engine bay fuse box. If its blown, or looks even slightly off, try swapping it.
-Check for power at the fuel pump. Details can be found in Bentley in section 160-6, but the gist of it is running the pump (via jumper) and listening if you can hear it and/or checking for voltage using your multi-meter (terminal 4/neg & 5/pos) at the harness connection. Power to the pump, but no pump activity when reconnected likely means shot pump (replace). If no power is supplied and/or jumpering the fuel relay doesn’t at least provide power, skip straight to trouble-shooting relays.
- Check for pressure/flow (if pump has power, and activates)
a. Pressure: Unhook the supply line IN at the RAIL in the engine bay and install a “T” with a fuel pressure gauge (nice kits are often available for rent at auto parts stores. They have expensive deposits, but you should get 100% of you money back upon return). Operate pump (via jumper) and check for around 51psi in M60/M50 and 44psi in M20/M30. Too high means blockages/kinks somewhere or the fuel pressure regulator is shot; too low means pump is shot or flow obstructed between pump and rail (clogged fuel filter most common culprit).
* Despite easier access to sending unit/pump in trunk, all pressure/flow tests should be done in engine bay because pressure from the pump doesn’t necessarily tell you anything about gas actually reaching the injectors (ask me how I know!...)
b. Flow: Disconnect RETURN line from fuel RAIL in engine bay and attach a length of hose to direct gas into a safe container from the rail. Operate pump with the jumper and you should get a nice stream filling approx a Quart in ~30 seconds. If you get a lot less, your pump may be shot (replace). “530IT” says he discovered during this test that a significant amount of what was pumping was actually water that somehow got into the tank, resulting in his no-start.
*you may want to try and blow air through the return line, pressure regulator, and fuel filters. Clogs or kinks can def be a problem. Never use compressed air over 87psi though! It could cause damage to lines/parts.
-Fuel Relay (locations vary): If the fuel pump gets power when you ‘jumper’ the terminal, but not when the relay alone is installed (and cranking with key), then its pretty clear the fuel relay needs to be replaced. If you get no power to pump either way, double check voltage to sockets with multi-meter, then see main relay.
-Main Relay: If you can get one cheap, I say swap it right away. Bentley section 130-6 has details, but with ignition OFF, you need to pull it and check for voltage at terminals 30 & 86. If that’s fine, plug in the relay and turn ignition ON. Then you need to get access under it (accomplished via two 10mm bolts that allow the entire relay row to come up out of box, careful not to disconnect wires though). From the bottom, check for ground at the brown wire (terminal 31). If there is ground, you’re good, if not the ECM signal is missing. If fine, check voltage at both “87” terminals to see if the relay is “energized and functioning”. If Power is at fuel pump, and relays are looking good, then it could be an ignition system issue.
-2. “Spark” IGNITION SYSTEMS:
- Check for spark: Bentley outlines easier ways in other engines, but for my m60b30 I had to pull a coil, pull a plug, pop plug into coil (still-connected harness), and ground the plug to engine bay (I used a heavy copper wire that I first wrapped around the plug, then wrapped around the threaded stud, that normally secures coil. I bent the wire so that it held the coil/plug upright where it was easily visible from the driver seat), BUT BE CAREFUL. The shock could theoretically and LITERALLY KILL you). Crank the engine and if you see spark, then it’s not your coil, plugs, or starter. If you don’t see a spark…
- Check Plugs and coils: Fouled plugs are hard to test, so I just bought new ones. Bentley section 120-4 outlines other engines, but the following info was, again, for an m60. For coil issues, first check for voltage to the coil connector harness (terminal 15/pos, ground/neg). IF no power, then you found your problem and trace back the wires to the fuses and/or relays. If voltage is present, test the coil itself for an ohm reading on your multi-meter. This really is more for if it runs like crap. As “Sir Montalbon” pointed out, the odds of 8 simultaneous failing coils leading to a no start is unlikely. Still, it only takes a few minutes and its best to be sure. Terminal 1/neg & 15/pos should give you of 0.4-0.8. Out of range = replace coil.
- CHECK YOUR CPS!!!: The bad CPS (on front of engine, under air boot) is arguably the most common issue for no starts on m50 and m60 engines. Disconnect and test it’s resistance with your multi-meter (terminals 1 &2)
Per ‘93FIM5’ “(if) This is reading below ~510-540 ohms I would say replace your CPS, that was my issue. The DME doesn’t see the engine cranking so it doesn’t initialize the pump or fire the plugs.”
*the Bentley says a 1280 ohms +/-10% reading should be present in m60 and m50 engines, but the m50 CPS listing is generally acknowledge to be wrong. The 550 range is actually correct. People with m60s have claimed to have both 550ohms AND others claim 1250. It was reported by “dreiko” that Pelican parts told him the CPS itself has been superseded so many times that the originals may indeed have read 1280 and perhaps newer ones fall in line with 540ish. Considering the fact there are drastically differing styles, including ones with plastic vs. metal housings, this is not hard to imagine. In any case, most agree that a truly shot CPS will read an insane number (like ZERO or a number in the millions), so if you are in the neighborhood of either ‘spec’ number, you’re probably ok. If you’re stuck though, when in doubt- swap it out.
-Check the injectors: Pop cover off the injector wiring ducts (tabs) and hook voltmeter to each injector. Pulsed voltage should be present 0.3-1.0 VDC while engaging starter. If not, check the red/white wire (pos) for voltage to the injectors.
*Resistance of a pulled injector should be 10-20ohms (~16 @room temperature) on m50, m20, and m30 engines. M60 injector’s resistance is stated by the Bentley to be “not available from BMW”…
3. OTHER (air intake, flooding, oddball/extreme occurrences):
-A 50A fuse in the E-box: (US passenger side of engine bay) was the cause of “Sir Montalbon’s” no start issue. It seems to be a fuse relating to the air intake in some way. Someone else may clarify…
-Engine Flooded: “sfgearhead” solved his problem by discovering he had flooded cylinders. He suggests pulling the plugs (only if you confirm you do have spark) and letting the cylinders breath and dry out. Crank the engine after pulling the fuel fuse to clear out trapped fuel. Be sure all components previously tested are back in place when attempting restart for real.
*“mannd” elaborates with these excellent instructions: “The M60B30 motor, especially high mileage motors typically will have low compression. When they flood they can be nearly impossible to start, fuel saturates the intake and engine oil. When you first pulled out the spark plugs, are they wet? If they are and seeing that you have spark, try the following..........”
1. Remove and dry out all spark plugs
2. With spark plugs out and DME relay removed crank over motor to evacuate cylinders.
3. Refit plugs and DME relay
4. Remove fuel pump fuse
**Get a second person to help with the following. Ensure battery is charged fully and use a good battery charger as this process will be taxing on the starter and battery**
5. With the accelerator to the floor at all times, start cranking motor until started then ease off (this is clear flood mode).
6. When you hear the engine trying to start have the second person momentarily fit the fuse and remove.
7. Continue this process until the engine starts.
-MAF: A dirty or faulty MAF may cause some problems. Check for voltage with multi-meter. The problem here, as I see it, is the Bentley says a faulty MAF “usually” will still let the engine “start and run” (it just runs like crap). A full blown non-start is, in my opinion, unlikely to be caused by the MAF. But hey, if you’re out of ideas or if you discover you’re not getting power to the MAF at all, def trace back the wires/fuses for issues and/or try swapping it.
-Air Filter: Super blocked/clogged one would def prevent strong running, and possibly choke out an engine. Check it for buildup, clean/replace it and give her another go.
-The DME: 93FIM5 reports you need a pin-out of the DME to accomplish anything. I am clueless on this topic. If anyone can chime in that would be great.
-The EWS II (security system) can possibly disable a starter. For more info on that see Porschedude’s informative thread http://forums.bimmerforums.com/forum...ws+porschedude
“KyleCleveland” suggests trying alternate key. If the EWS isn’t getting the “it’s all good” signal from a faulty main key, perhaps the backup key is still intact. Always worth a shot.
- The starter. I have no experience here, but I suspect this should only be a suspicion of your truly getting zippy for output/cranking/power. If its trying to crank, it shouldn’t be the starter.
-Blown Motor. Do a compression test and find out. I suggest you do the compression test while doing the “evacuate” process of trouble shooting the flooded engine. You will already have the plugs out and DME & Fuel relays unhooked, so you may as well slap a compression gauge in there and see what’s up while you’re at it. Harbor freight sells the gauges cheap.
-Incorrect valve timing. Particularly older engines. Very eloborate process, see Bentley sec. 116
To those reading this for fun, please share your own stories about problems AND SOLUTIONS to your no-start issue (ESPECIALLY if not already covered)!.
To those reading out of necessity, best of luck!!!
Could one of the Admins made this a sticky please?