Starting Problems after Rebuild - Need Help (96')

[roaminbmw]

I have a 96' 1500 4.3 V6...

I've finish a rebuild for both tranny and engine. Tranny was outsourced and engine was completed by me. I'm confident on the rebuild. Let me explain some details;
- all wiring is connected
- Tranny controls at linkage is in park, because starter does engage
- I have spark
- My timing is correct, and quadrupled checked. All marks lined up. ie. distributer, crank, cam. ( Cyl 1 at TDC on compression stoke and distrubuter alignment rotor for Cyl 1 spark) Otherwise theres not much more adjustment allowed on these engines.
- I have fuel pressure, I even double check injector port locations. To make I installed it correctly. Theres plenty of fuel reaching the cylinders because both the spark plug are observe wet of fuel when remove, and secondly it been observed flame coming from headers. Flame from the header was at the beginning of all my trouble shooting, I don't think this happen anymore.

Crank engine but no go.

This may sound redundent but I'm out of ideas.

During research there are things I wonder about.
a) Crank sensor - what does this exactly do? Spark timing? Injector Timing? I plan on testing as it is descibed in Chiltons. Does any one have more to add, other than whats stated there?
b) MAP sensor, ive read some threads on this forum about this. What is it, How do I check.
c) Are there other sensors to check that is needed for start up

d) Here somthing strange to me, The ground wire (frame to block) gets extremely hot when cranking. This does not seem right.

Ideas would be greatful, I hate to give up, We've spent a lot of time on it. Asking for help

[J-Ri]

Try getting a short section of 4 guage or bigger wire with bolt-on connectors on both ends. Remove a bolt (as close to the size of the hole in the wire end as possible) from any bracket on the engine (but I'd reccomend the alternator bracket). Use a wire brush and get the block and bracket as clean as possible. Put the bolt through the connector and torque it down. Drill a hole through the frame (unless a hole is available already) and bolt the other end of the wire to that. If you want, you can get a second cable and run it to the battery. Here, again, make sure the frame is as clean as possible before bolting it on. Get some undercoating or some liquid electrical tape and coat the new connections with it.

[planedude]

yeah for a quick try you can use booster cable run from the chassis to the eng.As J-Ri said. Also the crank sensor is for starting and running and could possibly be the culprite. Map sensor not really an issue for your prob.. I just replaced my eng and tranny in my 96 and I left the ground wire off. It is underneath the alternator bracket on the block an easy miss. I left mine on the shelf.....duuuu

[Fireplug]

Check for compression in all cylinders. You can have fuel ,air and spark but if no compression you have no fire( it will not start)

[roaminbmw]

Thanks for the replys...

Crank Sensor....
(a) I was thinking on my drive to work. All this sensor would do is determine RPM for your engine. Hence 'plandude' stated this is part of start up , I do agree, I will add its also part engine management. But I will need to test this out.

Compression is good, on avg. i got around 145, I had a low of 135 to high 155. I could tell you exacts, I have to check my notes. I verified compression prior to reintalling the engine back into the car.

(d) Seems to get some interest on grounding wire. For those interested its the braided copper wire. I will include the jumper cable idea as more grounding capacity as I con't to crank the engine untill I pin point the problem.

[Fireplug]

Did you spray fuel or good carb cleaner in the throttle body??? If not do so and see if it wants to start that way we can pin point if its fuel or spark problem

[acewelderman]

I had a park ave that would try to start but not quite make it . Replaced crank sensor & it started & purred like a kitten .Be careful to adjust clerance properly.Good luck!