Here's one for the tech gurus out there.
I've been a diesel mechanic for over 20 years so cars aren't quite my thing and I need help.
I have an '86 Fleetwood FWD with a 4.1L V8. It cut off going down the road and wouldn't restart (crank but no start). After the wrecker got me home I raised the hood, removed the air-cleaner, and attempted to start it. I found that it was back-firing through the throttle-body. I assumed that it had jumped timing. I got a new timing chain and gear set and installed them to the specifications in the manual and reset the distributor to it's #1 TDC firing position. All this work seems to have had no effect what-so-ever. It is still back-firing through the throttle-body and will not fire.
What could possibly be the problem? I have checked and rechecked the base timing for #1 TDC over and over again. It's dead on the money.

 

Unfortunately 81-87 4100 has a habit of wiping out cam lobes. I would suggest to pull valve covers and check valve action. Normally it will be 3,4,5,or 6 cylinders. In 88 along with growing to 4.5l they got roller lifters so one cam concern went away. 4.1-4.9l can have issues distributor gear wear - knife edging. Carbon build up, causing valve not to seat, on valves is also possible.