Cranks but won't fire?

canada karl · Post by **canada karl** » Wed Mar 21, 2012 8:12 pm

Now that Spring is here I decided to tackle the no start condition I left the 76 530i at last Fall. Here is the situation. The cylinder head has been changed to one from an 85 M30 but the cam is from the original head(better condition). I have lined up the cam as per the picture in the Faq with the crank pulley on TDC and the dist rotor pointing to #1
There is spark at points and spark at the plugs. There is fresh gas in the tank and a new gas filter. The engine cranks but won't fire! What am I missing here?

anthony · Post by **anthony** » Wed Mar 21, 2012 9:43 pm

Do you have fuel pressure? I have a fuel pressure gauge on my fuel line. I know that doesn't help you.

Can you hear the pump or get someone to listen? Right rear wheel well.

Mike W. · Post by **Mike W.** » Wed Mar 21, 2012 10:55 pm

Are you absolutely sure you're pointed at #1 and not 180 degrees off? Murphy's law says it happens 90% of the time, which I can confirm with empirical evidence. Even when right I usually have to putz around with it a bit and crank in 20 degrees more timing advance than seems right.

canada karl · Post by **canada karl** » Thu Mar 22, 2012 9:40 am

Can you walk me thru the procedure to double check if I'm 180 degrees out?When the valves are on the compression stroke the cam lobes are supposed to be on the low side not the pointed side correct? With a finger on the spark plug hole wouldn't you feel the air compression at two different times. How can you tell if it's the correct one?

Mike W. · Post by **Mike W.** » Thu Mar 22, 2012 9:46 am

Yeah, you've pretty much go it. You have to pull the valve cover and the cam lobes for #1 should be pointed down at the head with the valves closed. Oh, I should add one more thing, make sure #1 spark plug wire is where the rotor is pointed. I've seen it where the distributor isn't in the right spot, so to compensate the wires get moved to a different location.

tacomagabe · Post by **tacomagabe** » Thu Mar 22, 2012 10:24 pm

Was the car running before the head swap? I'm still a noob with diagnosing these things but while going through spark, air, fuel, it's easy to forget exhaust. I had a car with a bad cat in the exhaust and it would crank and not start. More likely then that though maybe you have a vac hose going to the wrong place/not attached in the head swap?

Firstfives.org

Cranks but won't fire?

Cranks but won't fire?

timing 180 degrees out?