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Car Forum / BMW Cars / April 20051988 325i possibly fuel pump related issue
Hi All, My '88 325i cranks but would not start. Fuse #11 is good. I am investigating the fuel pump system, removed the fuel pump relay and measured the voltage between the socket coresponding to terminal 30 of the relay and ground - it is battery voltage. Then I measured the voltage between sockets corresponding to terminals 30 and 87 and I get nothing. I have tried with a fused jumper wire that has a toggle switch as well but the bulb in the switch does not light up and I can't hear any noises coming from the fuel pump (because there is no voltage present at the fuel pump, I've measured there as well). At this point I'm stuck, what should I do next? Is this a fault somewhere in the wiring and if so how can I debug this through the maze of wires? I would appreciate very much any suggestions/ideas, maybe I'm on the wrong track investigating this problem? Thanks, Dan hey, i have the same car as you, where is the fuel pump on it, i dont feel like trying to find it:) > hey, i have the same car as you, where is the fuel pump on it, i dont feel > like trying to find it:) It is in the fuel tank - you have to remove the back seat in order to get access to it. However, the fuel pump relay is located in the engine compartment. Regards, Dan >Hi All, >My '88 325i cranks but would not start. Fuse #11 is good. I am [quoted text clipped - 14 lines] >Thanks, >Dan Pull the back seat and remove the cover over the fuel pump (passenger side). Remove the two pronged connector and put a test light across the terminal in the connector. Have someone turn the engine over. If the light comes on, buy a new fuel pump and enjoy driving your car. If not, post a reply here and we'll go from there. I'll guarantee your pump has died... > Pull the back seat and remove the cover over the fuel pump (passenger > side). Remove the two pronged connector and put a test light across > the terminal in the connector. Have someone turn the engine over. If > the light comes on, buy a new fuel pump and enjoy driving your car. If > not, post a reply here and we'll go from there. I'll guarantee your > pump has died... I have done the following tests and here are the results: FUEL System: 1. Using 2 wires I connected the fuel pump directly to the battery - the pump ran and delivered fuel (I had a hose with one end connected to the fuel pressure regulator in the engine compartment and the other end in a container to receive the fuel). So the fuel pump is good. 2. I removed the fuel pump relay and using a jumper wire I've connected sockets 30 and 87 then I measured the voltage between the terminals in the fuel pump connector - it was battery voltage - good. 3. I cranked the engine while watching the hose I had connected to the fuel pressure regulator to see if fuel was delivered. There was plenty of fuel - good. IGNITION System: 4. I tested for spark using a grounded spark plug connected to one of the wires that I had disconnected from one of the spark plugs. There were blue sparks while cranking the engine. So I have spark and fuel delivered to the cylinders but the car would not start at all... Could it be a timing belt issue? :-( If the belt has slipped how can I check that? Could it be that the valves are damaged? I don't hear any unusual noises coming from the engine when I crank it... Thx, Dan >I have done the following tests and here are the results: Is the check engine light on and if so, have you checked the codes? Silly question but... >FUEL System: >1. Using 2 wires I connected the fuel pump directly to the battery - >the pump ran and delivered fuel (I had a hose with one end connected >to the fuel pressure regulator in the engine compartment and the other >end in a container to receive the fuel). So the fuel pump is good. Good >2. I removed the fuel pump relay and using a jumper wire I've >connected sockets 30 and 87 then I measured the voltage between the >terminals in the fuel pump connector - it was battery voltage - good. Good >3. I cranked the engine while watching the hose I had connected to the >fuel pressure regulator to see if fuel was delivered. There was plenty >of fuel - good. Was this with the fual relay jumped or with the fuel relay in place? If the relay is jumped, try it with the relay in place. If it still gets fuel, this will rule out one possible ECU failure. The relay is grounded through the ECU. I remember you stating you checked the fuse so I won't go there. I am assuming you've tried to start the car since you've ensured you're getting fuel to the rail. >IGNITION System: >4. I tested for spark using a grounded spark plug connected to one of >the wires that I had disconnected from one of the spark plugs. There >were blue sparks while cranking the engine. This clears the reference sensor (had that go out on me). >So I have spark and fuel delivered to the cylinders but the car would >not start at all... Could it be a timing belt issue? :-( If the belt >has slipped how can I check that? Could it be that the valves are >damaged? I don't hear any unusual noises coming from the engine when I >crank it... This could be an ECU failure. Did you had to jump start the car or anything severe electrical happen right before this problem surfaced? I haven't heard of jump starting killing an ECU but it's probably possible. I know it can knock out the ABS system. If you're worried about the timing belt, pull the front cover and check it. For the $30 or so it takes to replace it (and the tensioner pulley) I'd do it while you have the covers off. If the belt looks good and most importantly the timing marks line up, I wouldn't worry about the valves. I'm leaning more towards a fuel issue. You have fuel to the rail but the injectors may not be putting it into the cylinders. I forget the details, but was the car running until recently or did you acquire the car in it's current condition? >Thx, >Dan > Is the check engine light on and if so, have you checked the codes? > Silly question but... The check engine light was never on while the engine was running (before it has started developing this no-start condition). Right now, since it does not start anymore the check engine light is useless I guess. > Was this with the fual relay jumped or with the fuel relay in place? > If the relay is jumped, try it with the relay in place. If it still > gets fuel, this will rule out one possible ECU failure. The relay is > grounded through the ECU. I remember you stating you checked the fuse > so I won't go there. I am assuming you've tried to start the car since > you've ensured you're getting fuel to the rail. The fuel relay was in place while cranking the engine and getting fuel at the pressure regulator hose. Yes, fuse #11 is good. > This could be an ECU failure. Did you had to jump start the car or > anything severe electrical happen right before this problem surfaced? [quoted text clipped - 6 lines] > valves. I'm leaning more towards a fuel issue. You have fuel to the > rail but the injectors may not be putting it into the cylinders. I had to jump-start the car about 2 years ago and after that the On Board Computer (OBC) started displaying PPPP Km/h, PPPP l/100km etc instead of the actual values. I had read after the fact that I was supposed to remove some fuses before trying to jump-start the car...well...I guess I fried the OBC in that occasion. However, the car has had an erratically hard-to-start condition when engine warm mostly (and sometimes when engine cold, sporadically) since I had the car (and that's 2001). That jump-start apparently hasn't affected anything else for the next 2 years. This hard-to-start condition, one cold December 2004 morning, all of a sudden became a no-start condition and since then I wasn't able to start the car anymore - it just sat in my garage for the duration of the winter and now I'm trying to put the pieces together on what this problem could be. > I forget the details, but was the car running until recently or did > you acquire the car in it's current condition? I've answered above. This past weekend I've checked the compression and these are the results: Cyl 1 2 3 4 5 6 Compression (psi) 140 140 140 135 130 100, 115, 120, 125 For cylinder #6 compression was 100 initially, then I've taken 3 more measurements and compression increased with each measurement as shown. The car has 192,000 km. Based on this I would say that the values indicate only worn piston rings and not damaged valves, right? And the engine should start even with lower compression on cyl #6. By the way, all the spark plugs were black and oily but I guess that's the result of endless crankings with no result in starting the engine. So you suspect that the fuel injectors might be at fault? How can I test them? Do I need any special tools? Assuming one or two injectors might have become defective, shouldn't the car still at least start (and run roughly afterwards)? Thx, Dan >The check engine light was never on while the engine was running >(before it has started developing this no-start condition). Right now, >since it does not start anymore the check engine light is useless I >guess. Maybe, maybe not. Might be a code that helps diagnose the problem. >The fuel relay was in place while cranking the engine and getting fuel >at the pressure regulator hose. Yes, fuse #11 is good. Ok, this is what I was trying to figure out. >I had to jump-start the car about 2 years ago and after that the On >Board Computer (OBC) started displaying PPPP Km/h, PPPP l/100km etc [quoted text clipped - 9 lines] >just sat in my garage for the duration of the winter and now I'm >trying to put the pieces together on what this problem could be. Ok, the OBC just has to be reset but that's a different problem. We'll resolve that later... >This past weekend I've checked the compression and these are the >results: [quoted text clipped - 9 lines] >all the spark plugs were black and oily but I guess that's the result >of endless crankings with no result in starting the engine. Compression is good for the specified mileage and would run if all else was good. Clean the plugs real good (or better yet replace them) and try again. Dirty plugs will foul and not fire the fuel mixture causing a no start condition. >So you suspect that the fuel injectors might be at fault? How can I >test them? Do I need any special tools? Assuming one or two injectors >might have become defective, shouldn't the car still at least start >(and run roughly afterwards)? I don't suspect the injectors themselves being bad. As you pointed out, one or two being bad the car would still start. After you clean or replace the plugs, turn the engine over and then pull a plug to see if you're getting fuel in the cylinders. The ECU could still be at fault but I'm willing to bet it's something simpler. Check the codes to see if there's anything stored as the computer keeps the codes until it is cleared and surely there is at least one code present after all of the attempts to start the car. The fuel injection system relies on several sensors to provide data in order to deliver the proper amount of fuel. If you're getting fuel to the cylinders, it's probably too little or too much which is causing the problem. Could be a stuck or bad mass airflow sensor, stuck or bad idle control valve or several other things. All of the sensors in the system are monitored by the ECU and it will know if one has gone south. > I don't suspect the injectors themselves being bad. As you pointed > out, one or two being bad the car would still start. After you clean [quoted text clipped - 10 lines] > several other things. All of the sensors in the system are monitored > by the ECU and it will know if one has gone south. Phycho, First of all I want to thank you for your taking the time to answer my problems with valuable suggestions, I really appreciate it. I will try to get the codes, clean the plugs and everything else and then I'll post an update here within the next day or so. Thx, Dan You can get the codes by pressing the gas pedal all the way to the floor five times with the key in the on (not start) position and counting the flashes. I don't have the chart handy on what the codes are but I'll look for it. >> I don't suspect the injectors themselves being bad. As you pointed >> out, one or two being bad the car would still start. After you clean [quoted text clipped - 20 lines] >Thx, >Dan > You can get the codes by pressing the gas pedal all the way to the > floor five times with the key in the on (not start) position and > counting the flashes. I don't have the chart handy on what the codes > are but I'll look for it. I've replaced the spark plugs with brand new ones and...the first cranking I did, the car started for a split second and died right after. Subsequent tries yielded no more positive results, back to no-start condition. I removed 4 plugs and looked at them, they were smelling gas, but weren't wet, well maybe just an idea...I'm not sure what I should have seen, should they have been soaked? I'm thinking maybe the injectors are not opening because of lack of signal from the Motronic unit... I had no luck trying to getting the codes...the moment I switch the ignittion on, the check engine light starts blinking regularly (approx 1 blink/sec) and is unaffected by my pressing the gas pedal. I've tried pressing it to the floor 5 times within 5 seconds several times at different speeds and switching the ignittion off and on between tries. Nothing but the constant, uninterrupted blinking that does not tell me much. Any suggestions? Thanks, Dan I have included a link that lists the fault codes in case you hadn't found them. The fact that it started does at all does indicate the ECU/injection system IS working. There is something that is too far out of parameters preventing it from running. You definitely need the ECU codes, whether you get them from the CEL or a code reader. I don't think there's any way around this one other than to just guess and start replacing parts. PROHIBITIVELY expensive and not the way I would want to go. http://www.verrill.com/car/idle/e30_idleproblem.shtml >> You can get the codes by pressing the gas pedal all the way to the >> floor five times with the key in the on (not start) position and [quoted text clipped - 20 lines] >Thanks, >Dan Yesterday, after weeks of investigation finally I was able to start the Bimmer! I think I've checked pretty much everything (except the timing belt which I was about to check this weekend) and I was kinda desperate because everything so far was checking ok. The last thing I checked was something I wasn't expecting much from, the idle air stabilizer valve. Took it out, submerged the half mechanical part of it into some carburator cleaner for the night, made sure the inner cylinder is moving freely (before cleaning it it wasn't moving that good), assembled it back and...the car started like a charm! I would not have believed that this idle part thing could have such an importance that the car would not start...I mean not even the computer could not compensate for the excess air...and the book didn't mention that this part could lead to no-start conditions...only idling problems... So after all, everything amounted to some cleaning...was that simple...but how many headaches! Thanks to everyone who helped me with their suggestions. Before finishing, I would like to post another question: how do I reset the OBC so it doesn't display PPPP anymore? This started happening after jump-starting the car 2 years ago. I have disconnected the battery several times since then but it did not help reseting the OBC. Regards, Dan > I have included a link that lists the fault codes in case you hadn't > found them. The fact that it started does at all does indicate the [quoted text clipped - 6 lines] > > http://www.verrill.com/car/idle/e30_idleproblem.shtml >Yesterday, after weeks of investigation finally I was able to start >the Bimmer! I think I've checked pretty much everything (except the [quoted text clipped - 10 lines] >that this part could lead to no-start conditions...only idling >problems... It should not have prevented it from starting if you feathered the gas pedal while starting. If it were stuck closed, the car wouldn't idle. Stuck open, it would idle but run lean. Doesn't matter as it fixed the problem. After rereading one of your last posts, I should have caught the IAC valve. Sorry about that. >Before finishing, I would like to post another question: how do I >reset the OBC so it doesn't display PPPP anymore? This started >happening after jump-starting the car 2 years ago. I have disconnected >the battery several times since then but it did not help reseting the >OBC. Unplug the cable from the back of the OBC for a few days, this seems to clear out whatever residual electrical charge that keeps it from resetting. >>Yesterday, after weeks of investigation finally I was able to start >>the Bimmer! I think I've checked pretty much everything (except the [quoted text clipped - 14 lines] > gas pedal while starting. If it were stuck closed, the car wouldn't > idle. Stuck open, it would idle but run lean. Actually, that is incorrect. The IAC is *after* the AFM (Air Flow Meter) and is merely an air bypass around the main throttle plate. This means the mixture will remain the same richness (or lean-ness) regardless of how open or closed the IAC valve is. So if it was stuck open it would just have a very high idle. Stuck closed would be low idle speed and stalling. -Fred W |
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