M20 Running Problems

[camip]

The car is a 85 m20b27. The car will start right up and die immediately. Injectors are pumping fuel and the car has spark. The car will stay running if I keep the starter cranking but dies once the key is on the on position. I originally thought it was the cps but if that was bad the car wouldn't even start right?

[spdracrm3]

right the fact that its starts while cranking means cps is working , sounds like you are losing voltage to injection/ign system when key is in run position i would pull up a diagram and find out which wires at ign switch need to be hot in "run " position and check at the switch

looks like green and violet wire (green being mostly associated with IGN/INJ system)


find your ETM diagram here

http://www.wedophones.com/BMWManualsLead.htm

[camip]

Thanks looking into that now. Well I found the right diagram but I'm having trouble I'm not sure what to look for exactly.

[camip]

Here's the diagram

[spdracrm3]

thats just the start circuit ,you have to look thru the sections on injection and ignition to determine how the power flows it can be tedious if you dont understand diagrams well (positive 12v at top of diagram and ground at bottom), i looked thru and it looks like the violet and green at ignition switch are "hot" with key in "run" and the injection and ignition both feed off the green wire at ignition switch. check with a voltmeter or test light to make sure the green stays hot cranking and key released in "run " position

section 123 ignition 124 "fuel delivery " injection

[camip]

Ok tomorrow I'll grab the multimeter and check out if its staying 12v on run thanks a bunch man.

[jlevie]

It sounds to me like you have a bad ignition switch.

[camip]

It sounds to me like you have a bad ignition switch.

That's what I was thinking. Just want to make sure before I start ordering parts.

[camip]

So both green and green/violet are hot with the key on run :( at a loss now.

[spdracrm3]

well on to the next in line then, check power at ignition coil and main/fuel pump relays both cranking and key in run position. green wire at 15 terminal of coil, green wire pin 86 of main relay, red/wht pin 86 fuel pump relay. red pin 30 fuel pump relay. (bottom pages of ETM's show component locations)

do you have an on board computer OBC ? 13 button in center console ,they have a code setting feature that can stop car from starting if set ,but i dont think it would allow it to run period unless someone has messed with wiring

[camip]

Could it be a tps or afm because I was having idle problems for a few weeks before she died on me. I don't think a vacuum leak is the problem because it would have to be a giant ass vacuum leak.

[camip]

well on to the next in line then, check power at ignition coil and main/fuel pump relays both cranking and key in run position. green wire at 15 terminal of coil, green wire pin 86 of main relay, red/wht pin 86 fuel pump relay. red pin 30 fuel pump relay. (bottom pages of ETM's show commponent locations)

do you have an on board computer OBC ? 13 button in center console ,they have a code setting feature that can stop car from starting if set ,but i dont think it would allow it to run period unless someone has messed with wiring

All these tested hot on run.

[spdracrm3]

will the engine stay running if you apply gas pedal ? try disconnecting AFM and see if it will run.

if you have someone that can assist you try starting and have them pull the starter solenoid wire once the thing is running (this will obviously stop the starter engaging ) and see if one it will stay running with key held in start position and will rev up,and then let go of key and see if it still stalls

[camip]

will the engine stay running if you apply gas pedal ? try disconnecting AFM and see if it will run.

if you have someone that can assist you try starting and have them pull the starter solenoid wire once the thing is running (this will obviously stop the starter engaging ) and see if one it will stay running with key held in start position and will rev up,and then let go of key and see if it still stalls

I'll try this in the morning. Most likely taking the car to a shop. I'm in over my head at this point.

[camip]

Thanks for you help a bunch. Thanks to you I at least went down with a fight.