unreliable start.

[E30_(1st Musk)_]

ok heres the deal.. the car used to stop as i was driving... it was fixed.. now the deal.
1. in the morning it takes to long to start.
2. even when the car is hot after driving for hours. when i turn it off sometimes it still wont turn on.(low or high on gas)

im thinking its some kind of sensor. other than that im at a lost..
help dudes..
thanx.

[E30_fiend]

Cps

[Philo]

I had a similar problem with my reference sensor/CPS, but don't cross out other possibilities.

When starting your car, turn the key to the on position, let the fuel pump prime for 5-10 seconds, then start. If this takes care of the problem, it is a fuel delivery problem.

[jlevie]

The fuel pump is controlled by the DME and it only runs when the DME sees timing data from a rotating engine. So leaving the key in the on position for a few seconds will have no affect of the fuel system.

If the fuel system is in good operating condition, the rail will come up to operating pressure after a couple of turns of the engine, even if the system pressure has gone to zero. A weak pump, clogged filter, bad FPR, or clogged line can result in more cranking time required to reach operating pressure in the rail. This is easily diagnosed by running the fuel system test suite documented in the Bentley manual.

Hard starts can be caused by a number of faults, but the most common cause is an intake leak. That is best diagnosed by having a smoke test run on the intake.

[E30_(1st Musk)_]

I had a similar problem with my reference sensor/CPS, but don't cross out other possibilities.

When starting your car, turn the key to the on position, let the fuel pump prime for 5-10 seconds, then start. If this takes care of the problem, it is a fuel delivery problem.

yea i was thinking that it was that sensor but i wanted to check my guess. i dont know exactly how to check it or replace it. but soon i will get a bentley manual and do what i can. And ill try what you suggested about leaving it for 5-10 seconds.

[Philo]

You will need a multimeter. To test reference sensor: pull plug located @ 4:30 (from front of car) next to the diagnostic center and the oil dipstick. Looking from the drivers side of the car it is the sensor on the left in the two bay area. Pull the rubber shield around the end to reveal the color of the wires. Test the black and yellow wire with a multimeter. You should get 540 +- 54.