84 944 Will Not Start

[bmwbeemer7]

I just purchased a 1984 944 and it has been sitting for about a year. It will not crank. The engine turns over but it will not crank. I put a new fuel pump, dme relay, and 4 new injectors and still nothing. Today when i installed the new injectors that they are not putting out any gas at all. Gas is getting to the fuel rail when I run a hot wire straight to the fuel pump but it does not come out of the injectors even with the key in the start position. Does one of the round metal canisters on the rail control the fuel flow trough to the injectors? I did notice that the plastic lines to the one on the left side closer to the battery are separated. Any info will be Extremely appreciated. Thanks, James

[blown 944]

I had purchased a similiar situation and it took getting some good fuel to it to get it to fire up.

I would check:

1)Compression (Pull front cover and inspect the t belt, chances are it will need replaced immediately)
2) reference sensors behind intake manifold
3)Spark

If they pan out try separating TB /AFM boot and spraying some gas in there and see if it will fire. If it does I would check to see if injectors are getting any power. Unplug one and use a Voltmeter and have someone crank it if you get any voltage at all chances are you have some bad fuel. If not you most likely have a bad connection to the DME and possibly a dead DME. You could check voltage at AFM to determine what the DME is doing.

Good luck and remember to change the t-belt immediately
Sid

[bmwbeemer7]

Thanks I'll check them all in the morning. The injectors are getting power when I turn the key and I can hear the gas enter the fuel rail when I put a hot wire directly to the fuel pump but still nothing comes from the injectors. James

[many944s]

^+1.
On several occasions I have seen oxidation work it's way into the connector for the reference sensor (located at the top rear of the engine). If the DME does not get a signal from these sensors, it will not fire the injectors, and you will not get a spark. If you are not getting spark as well, try disconnecting these sensors and re-seating them. Just make sure you get them re-connected to their respective sockets, or you will never get it started! The connectors should be located on an upright bracket at the rear of the engine just in front of the firewall.

That is where I would start.
-Nick

[Razorback1980]

The round metal canisters you are talking about are the fuel pressure regulator and dampner. That is what sets the fuel pressure on the fuel rail. If there is no vacuum to them, the injectors have full pressure.

Check for voltage at the injectors. If none, then you may want to look at the wiring or make sure your dme relay is working properly. The wiring has a splice in it that sometimes causes problems. You can buy an noid light that attaches to the connectors to help determine if they are receiving voltage.

Also, check out clarks-garage.com if you haven't already.

Keep us posted.

[SoCal Driver]

First the fuel pump should not be running with the key on. Runs only when cranking the engine and after the engine starts.

Second even IF you hot wire the fuel pump (aux fuse 2 to 3) fuel does not come out of the injectors unless there is fuel pressure AND you are cranking the engine AND the DME is getting current AND the reference sensor is working.

You "crank" the engine by using the starter. Either the engine starts or does not start. Need to be clear on this.

When a 944 sits for a year you need to flush the fuel system and replace the fuel filter. You can do this by running the fuel pump with the jumper across the two fuses. IF the fuel pump runs, most are varnished up from sitting, all of the sediment in the tank will be trapped in the fuel filter. You will need to replace the fuel filter.

If the fuel pressure regulator and/or damper is shot you may get too much pressure in the fuel rail or not enough. It's usually too much. This will hold the injectors closed. Also the fine sediments will clog the inlet wire mesh filters on the injectors. Back flushing the injectors with solvent and shop air will clear them.

Still first things first: Turn the key on and check for battery voltage at the coil (black wire) and at one of the injector connectors. If there is no voltage at the coil then the ignition switch is bad. If there is voltage at the coil but not at the injector then the DME relay is acting up. If there is voltage at both you need to pull a spark plug wire, stick a spark plug in it, lay the plug on the intake manifold and crank the engine looking for spark across the plug gap.

No spark check that the rotor is turning, the HV cable from the dist to the coil is good (comes loose inside the weather boots) and that the plug wire you used is good. Pull the spark plug wire out of the dist cap and stick it in the coil and crank the engine again. If you have spark then pull the dist. cap and look for a loose rotor or a broken timing belt.

Another reason for no spark is the reference sensor (front one of the two) is not seeing the pin on the flywheel or if it is sensing the pin the DME is not responding to it's signal. There are a few places inside the DME where the solder joints crack and separate -- one is the large transistor that triggers (grounds) the coil. Could be that the sensor is out of adjustment or is damaged; bad connector or has hit the pin on the flywheel or even hit the pin and bent or broken it off. Most find that the connector is loose or corroded or cracked or all of the above.

If you do get it started replace the timing and balance belts ASAP. Especially if you have no idea when they were last replaced.