Serious fuel injection problem.

[estrada42]

I've been trying to fix a fuel problem on my 89 525i 5-speed for a few weeks now, and searching just isn't fixing my problem.

I went to show the car for sale and the car started and idled fine. After the car warmed up, there sounded like there was a misfire. After giving it some gas three cylinder stopped firing all-together.

I limped the car (about .3 miles of flat surfaces) and pulled the engine code via the pedal stomp. Got code "1251 Fuel Injector 1 (or group 1)". I took my results to a mechanic friend of mine and he suggested resistance checking all the injectors and making sure there in spec. Also to try dis-connecting an injector at a time and see if the other five fired up.

All the injectors measured at either 15.8 or 15.9 ohm. If I disonnect any of the injectors, the car won't start at all. Right now the car starts but only runs on three cylinders.

My next thought is to test what ever it is that triggers the injector grounp to fire. Also to check and see if the injectors are getting a signal in the first place.

So my question is, whats the next step? Whats the next test I can try to get this car back on the road? Any thought? TIA.

[Bill R.]

starter and in front of it. The 2 groups of 3 injectors each fasten at this connector. If there's a problem with this connection you can lose one group of 3 like you did. Also on your car the sensor for the injectors is on one plug wire but even if it was bad the injectors would still trigger they just wouldn't trigger semi sequentially. So its not a sensor problem. Its most likely at that connector by the starter, if not check the harness from that connector up to the bad injectors for continuity, If there is no problem in the harness then its most likely the DME itself. I personally would suspect the connector though.

I've been trying to fix a fuel problem on my 89 525i 5-speed for a few weeks now, and searching just isn't fixing my problem.

I went to show the car for sale and the car started and idled fine. After the car warmed up, there sounded like there was a misfire. After giving it some gas three cylinder stopped firing all-together.

I limped the car (about .3 miles of flat surfaces) and pulled the engine code via the pedal stomp. Got code "1251 Fuel Injector 1 (or group 1)". I took my results to a mechanic friend of mine and he suggested resistance checking all the injectors and making sure there in spec. Also to try dis-connecting an injector at a time and see if the other five fired up.

All the injectors measured at either 15.8 or 15.9 ohm. If I disonnect any of the injectors, the car won't start at all. Right now the car starts but only runs on three cylinders.

My next thought is to test what ever it is that triggers the injector grounp to fire. Also to check and see if the injectors are getting a signal in the first place.

So my question is, whats the next step? Whats the next test I can try to get this car back on the road? Any thought? TIA.

[estrada42]

starter and in front of it. The 2 groups of 3 injectors each fasten at this connector. If there's a problem with this connection you can lose one group of 3 like you did. Also on your car the sensor for the injectors is on one plug wire but even if it was bad the injectors would still trigger they just wouldn't trigger semi sequentially. So its not a sensor problem. Its most likely at that connector by the starter, if not check the harness from that connector up to the bad injectors for continuity, If there is no problem in the harness then its most likely the DME itself. I personally would suspect the connector though.

I can't really find a 7-pin connector. There's a black block-off plate right infront of the starter, is it behind that?

[estrada42]

Is this it?
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[Bill R.]

.

I can't really find a 7-pin connector. There's a black block-off plate right infront of the starter, is it behind that?

[estrada42]

The connector doesn't come loose. It seems to have a screw ring around the connector that doesn't come loose or come off. Or am I being too much of a sissy?

[Blitzkrieg Bob]

The canon plug side is facing down, so it is easier to unscrew by reaching it from underneath.

It's a little tight, but it comes off once the plug is unscrewed.

[estrada42]

Okay, did some testing this afternoon. Here's what I've found.

I decided to check for continuity between the DME connector and all 6 injectors. No problem there.

I also checked to make sure I had the correct voltage at the DME connector with the key on, engine off. Everything check good here as well.

At this point I'm fairly confident it's the DME itself. Untill I decide to manually fire the injectors.

I ran a jumper whire from pin 17 to battery ground. I can hear half the fuel injectors spray. Pin 17 is group 1 (injectors 2, 4, and 6).

I do the same with pin 16 ( injectors 1, 3, and 5) and find that nothing happens. Just a light single click, then nothing.

Now I'm really confused. Any thoughts?

[Ross]

Are you sure the injectors are not working in the odd/even groups? Maybe some aren't getting the power to open, maybe a break in the 12V side of the circuit.

[estrada42]

With the key on/engine off, I've got battery voltage at pins 16 and 17 of the DME connector. If there was a break in the circuit, I wouldn't have power there right? Since it's the last stop on the circuit before ground, if there was a break in an injector harness, then there shouldn't be power, right?