My uncle takes it to work one day and it's working just fine. He works from 7:30 to 5:00. He gets ready to go home and the engine rotates but doesn't crank.

He checked for a spark and there was NO spark.

1990 XLT, 2.9L V6 fuel injected, manual transmission

 

What do you mean the engine rotates but doesn't crank?

You mean it cranks but doesn't fire?

 

sure you can say that, same thing.

 

No, lol, not the same thing. I assume when you say the engine rotates you mean that it cranks. So it cannot "rotates, but doesnt crank".

So he's not getting a spark. What year truck is this on?

 

1990 XLT

 

What engine, transmission, etc?

 

2.9L V6 fuel injected, manual transmission

 

Hmm Idk anything about those engines. :( I'll wait and see if somebody else can reply.

 

alright.

 

EDIT your first post to include information on the truck (Year, engine, transmission, etc) so that anybody that reads the thread doesnt have to search the thread for info about your truck...

 

The "Running fine when I shut it off , now won't start" is a classic symptom of a stretched timing chain or belt that has jumped a tooth or 12 on an older vehicle.
When an engine is shut down ,at the end of its revolutions the crank shaft has a tendency to 'pop' backwards a few degrees.any slack in the timing chain or belt will allow it to jump a few teeth on the crank gear.

 

You need a handful of things to get an engine started. Spark fuel and compression is the 3 key ones to worry about. Pull out a plug make sure they aren't fouled to bad and that they still have spark. If you have spark then make sure you have fuel. Take a pressure reading at the rail. I forgot what the specs are supposed to be on that maybe somebody can chime in with the answer. If you have spark and fuel check for compression. If you don't have compression its most likely a timing chain problem. If you have spark fuel and compression come back and ill really scratch my head :)

 

We do not have spark at all which would indicate the problem is in the ignition system. The ignition system is the distributor, ignition module and the central computer that creates the spark.

 

Give this one a look.... TFI module

What is a TFI module?
The TFI stands for Thick Film Ignition. The module itself consists of some solid state electronic components suspended in a thick, clear electrolytic film, hence the name TFI.

What is the TFI module's function?
The TFI module (also known as a spark module) is necessary to control the spark output of the ignition system via the EEC (electronic engine control) computer. A signal from the TFI module is sent to the EEC and the computer then controls the spark to the spark plugs. It is a very necessary and vital component of the entire EEC-IV engine management system.

 

I second the TFI module as a possible culprit, IIRC the module was still mounted on the distributor in 1990. Not only was there a recall due to fire caused by these modules, but they were also highly suspectible to heat (Which is why in later years they moved the module to the fender, and off of the distributor).

Remove the module and take it to your nearest big box parts house (O'Reillys, Checkers/Schucks/Kragen, AutoZone or Advance Auto), they test these modules for free.