Fuel Delivery Issue

[KenC]

I have an issue with the fuel injection system in my M42.

A few times over the past two years, the car hasn't started up and will just crank and crank.

Too much fuel is being dumped into the cylinders on either start up or shut down, which washes away the oil on the walls and causes low compression. (putting a cap full of oil in each cylinder and letting it sit for 10min will make the car fire right up and run smoothly).

The fuel pressure regulator has maybe 10k on it as I replaced it late last Summer.

I'm thinking it's leaky injectors, but the problem seems to be VERY intermittent. It seems like the injection system is either dumping too much fuel on start up or the injectors are leaking a significant amount on shut down. But again, this is a VERY intermittent issue.




Some one on M42club thought it could be the ICV, but I'm not sure how that would cause this problem.

[wolfgangstbd]

are you fuel pressures good. you could just take the upper portion of you intake off and peek at the injectors and see if its wet/dirty around any if you think they are leaking

[e3o-master]

leaky injectors/bad o rings

[individualist]

Does this happen when the motor is warm or cold as in sitting overnight cold?

[Cobra Jet]

Ken - have you tried extracting any fault codes? Has your CEL illuminated at all?

I would check the CPS (crank positioning sensor), it's a common failure item on the M42's and when it does fail, the DME will not store a code for it - nor will a CEL event occur. There is an actual fault code for a failed CPS, however, for whatever reasons unknown to many, the M42 DME will not store or capture that fault code for a failing (or failed) CPS. Test the CPS per the Bentley - if your results are higher or lower than the printed resistance values, replace the CPS. A failed CPS affects spark and fuel delivery.... When a CPS is failing, you will experience sporadic hard starting issues, possible stalling while driving, fluctuating idle, or when it finally goes - the vehicle will NOT start at all (and again, there will be no stored codes).

Have you tested your fuel pump, fuel pressure regulator?