Solve this mystery

[Taragon]

I once had a 89 2.9 that backfired ONCE as I was shifting into 2nd gear. It went dead, and never started again.

I had fire, fuel, and a clean air path. Timing was dead on and not worn or loose. No coolant leaks and perfect compression with no leaks. No broken rods, valve springs, bend vavles, or holes in the pistons. No cracks in the block, or blown head gaskets. Neither the cam nor the crank was broken. No knocks when trying to start. No cracks in the heads, or upper or lower intake. No spun main or rod bearings.

So I replaced the motor with one from an 87. Used the distributor, TFI module and EXACT same sensors and wiring from the "old" 89 motor...none of the "new" 87 motor wiring was used AT ALL! Fired right up, and has ever since.

So you tell me what may have went wrong. TO THIS DAY no one has been able to find the problem.

 

[IMenriched]

Sounds like the interia switch was tripped. when you did the engine swap you disconnected the battery and reset everything, including the engine computer any stored codes were eraced. or at least when reattached the wires made better connection ...just a few thoughts

 

[Taragon]

If the inertia switch had tripped, I wouldnt have gotten fuel pressure to the motor.

And the fuel pump wouldnt have kicked on when I cycled the key.

 

[Taragon]

I see you guys are as stumped as I was/ STILL am!

 

[pillen140]

broke crankshaft? did the starter crank? possesed

 

[IMenriched]

another possibility was that some carbon broke loose & lodged under a/several valves.
need some compression to complete the running equation. IF, as you say, everything was correct... fuel, spark, air & timing.

so you haven't tore the engine down to find out??

 

[grnrngr]

Could have been a connector that just came apart far enough to lose contact but still look like it was connected...