i sent this email to the guy online w/ all the m42 318is info... can't remember his name. i'm posting it on here in case anyone has ideas. thanks.
I am writing you because you seem to be the most knowledgeable person on the 318is around. I have had my 318is since may, and it only ran for approximately 1 month before shutting down.. never to be started again so far.
The problem began as a kind of “sputter” and progressed to the point where it ran so roughly that driving it was impossible. I started by making some sparkplug wires but that changed nothing. What I diagnosed as an ignition problem soon seemed to be a fuel issue instead. I suspected this all along because from the day I picked up the car, it had a leak when it was over ¾ full, and would sputter and quit running below ¼ (as if the gauge read incorrectly and ¼ tank was actually empty).
I pulled the rear seat and then the fuel pump to find that some kind of replacement pump was being used rather than the stock unit. It was simply dangling in the tank by the feed line and was neither bolted nor fastened in anyway. Additionally, It’s “sock” or filter on the pick up end of the pump was covered in muck. My friend had just wrecked his 87 325is, so I robbed his car of it’s in tank pump and installed it in mine. I’m sure you’ve recognized the fault in my reasoning on this move. The in tank unit from the 325 is a low pressure high volume pump and is supplemented by an out of tank high pressure pump. With that pump installed, I found that fuel pressure had dropped significantly, and the car wouldn’t even start. With a little research, I discovered what I’ve already told you, the pump I installed was only a feed pump, not for pressure.
Realizing my mistake, I thoroughly cleaned the pump that came in the car, installed it back as it was, and tried to start the car again. NOTHING. Not even the slightest hint of combustion. Since then, I have tested the injector signal by putting noid lights between the plug and the injector to indicate whether or not there was a signal reaching the injectors. There was a signal, but it was very erratic. It seemed to have no regularity or rhythm to it at all. I then put a light between the plug wires and the spark plugs, that tested out perfectly. This leads me to my first question: What should the signal from the computer to the injectors “look like”. Should it be a regular signal, or is it actually designed to be quite erratic?
Next, I decided I would remove the fuel filter and see just how much crud was being sent towards the injectors… maybe they were clogged. I found NO filter. After about an hour of searching, I found where it should have been. Instead of a filter, there was a metal tube clamped in its place. The car had been receiving unfiltered fuel for who knows how long from a pump dangling on the bottom of the tank (who’s pickup filter was absolutely filthy). I am now thinking that perhaps the injectors are clogged, but before I jump to conclusions and start replacing them I figured I’d check with the expert. It HAS been a shop for some time now and they can’t seem to figure it out.
We have also replaced the afm, and also tested the crank and cam position sensors. There IS a “mysterious” black box that I am assuming is a wiring junction box that is located beneath the intake manifold. Into the box run nearly all sensors as well as wiring from the dme to the injectors. I think it is a possibility that there is a wiring issue in there. Unfortunately, I am having trouble getting any kind of detailed schematic for the wiring under the hood of the car… its not in the snap on online reference, and most manuals go through 90 and pick back up in 92 (completely skipping my 91 model car).
That is all I can think of right off hand. If you have any advice I would appreciate it very much. Thank you for your time.
Sincerely,
Joe Harwell
I am writing you because you seem to be the most knowledgeable person on the 318is around. I have had my 318is since may, and it only ran for approximately 1 month before shutting down.. never to be started again so far.
The problem began as a kind of “sputter” and progressed to the point where it ran so roughly that driving it was impossible. I started by making some sparkplug wires but that changed nothing. What I diagnosed as an ignition problem soon seemed to be a fuel issue instead. I suspected this all along because from the day I picked up the car, it had a leak when it was over ¾ full, and would sputter and quit running below ¼ (as if the gauge read incorrectly and ¼ tank was actually empty).
I pulled the rear seat and then the fuel pump to find that some kind of replacement pump was being used rather than the stock unit. It was simply dangling in the tank by the feed line and was neither bolted nor fastened in anyway. Additionally, It’s “sock” or filter on the pick up end of the pump was covered in muck. My friend had just wrecked his 87 325is, so I robbed his car of it’s in tank pump and installed it in mine. I’m sure you’ve recognized the fault in my reasoning on this move. The in tank unit from the 325 is a low pressure high volume pump and is supplemented by an out of tank high pressure pump. With that pump installed, I found that fuel pressure had dropped significantly, and the car wouldn’t even start. With a little research, I discovered what I’ve already told you, the pump I installed was only a feed pump, not for pressure.
Realizing my mistake, I thoroughly cleaned the pump that came in the car, installed it back as it was, and tried to start the car again. NOTHING. Not even the slightest hint of combustion. Since then, I have tested the injector signal by putting noid lights between the plug and the injector to indicate whether or not there was a signal reaching the injectors. There was a signal, but it was very erratic. It seemed to have no regularity or rhythm to it at all. I then put a light between the plug wires and the spark plugs, that tested out perfectly. This leads me to my first question: What should the signal from the computer to the injectors “look like”. Should it be a regular signal, or is it actually designed to be quite erratic?
Next, I decided I would remove the fuel filter and see just how much crud was being sent towards the injectors… maybe they were clogged. I found NO filter. After about an hour of searching, I found where it should have been. Instead of a filter, there was a metal tube clamped in its place. The car had been receiving unfiltered fuel for who knows how long from a pump dangling on the bottom of the tank (who’s pickup filter was absolutely filthy). I am now thinking that perhaps the injectors are clogged, but before I jump to conclusions and start replacing them I figured I’d check with the expert. It HAS been a shop for some time now and they can’t seem to figure it out.
We have also replaced the afm, and also tested the crank and cam position sensors. There IS a “mysterious” black box that I am assuming is a wiring junction box that is located beneath the intake manifold. Into the box run nearly all sensors as well as wiring from the dme to the injectors. I think it is a possibility that there is a wiring issue in there. Unfortunately, I am having trouble getting any kind of detailed schematic for the wiring under the hood of the car… its not in the snap on online reference, and most manuals go through 90 and pick back up in 92 (completely skipping my 91 model car).
That is all I can think of right off hand. If you have any advice I would appreciate it very much. Thank you for your time.
Sincerely,
Joe Harwell
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