BMW won't start

My buddy has a 1989 325lx BMW. When it is cold -5 c to -10c it has no problem to start . When it sits parked in a warm garage or if it is above 5 degrees c it won't start. Any ideas?


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you gotta give us more information....
-do the accessories work
-is it cranking
-is it an electric fuel pump, if so can you hear it come on?
more info or no answer

Very true... more info.

I don't think the 89s had it, but a common failure point is the 7th injector. There may be an enrichment injector on the passenger side of the plenum that acts like a "choke" when its cold. Its a common failure point.

If it doesn't have a 7th injector, look to the coolant temp sensor. That is another common failure point.

The car does everything normal except it appears not to be getting gas when it is warm outside. we drilled a hole in the intake manifold and sprayed some gas in and the engine starts. It doesn't have a seventh injector. Is there anyway to trick the coolant sensor?

Wait... you drilled a hole in the intake? Why didn't you just take off the vacuum plate on the plenum? Could the problem be that you now have destroyed the cylinder walls and valves with metal shavings?

No tricking the coolant temp sensor. It tells the computer how hot the coolant is by using resistance. Unless you measure the exact resistance, compare it to what it should be, and install a resistor or amplifier to make up the difference. That might work for one day, but as the sensor continues to fail it won't work any more.

They're $7, just get a new one.

Anyway... test the resistance of the CTS. Then test the Fuel pressure relay. Then your car has two electric fuel pumps; one is in the tank which is accessible under the back seat. The second one is along the driver's side frame rail near the fuel filter. While you're at it, check the fuel filter. Pull the plug wires off and test for spark. If its not hot enough, test the coil. If it gives you more than 6 ohms on the low side and .6 on the high side, replace it.

you could check the reverse wobble joints near the muffler bearings....