Greetings Bluetieguy53,
If I can restate your symptoms, your TBI engine starts fine cold, but won't start hot. (Unless you first disconnect
the injector leads and get the engine to burn off the fuel already in the intake manifold?) And other than this the
engine runs well?
This sounds like a specific failure footprint that the TBI system suffers when the ECT (Engine Coolant Temperature)
loses it's calibration & misleads your computer into thinking that your engine is cold when it is NOT, leading to
the computer commanding a way too rich Air/Fuel ratio, flooding the engine when attempting a hot start. (!)
By the way, the next time this problem occurs, instead of disconnecting the injectors I would like you to instead
stomp the gas pedal right to the floor while cranking. When the computer sees the wide open throttle during
cranking it will go into the "
Clear Flood" mode. (See 1st attached.) The computer will cut way back on the fuel delivery,
and this will allow your engine to start. If flooring the gas pedal during a hot start works, then this symptom would
confirm to me that you are indeed suffering from too much fuel during hot start up.
The Factory Service Manual has a simple diagnosis involving testing the resistance that the ECT is reporting to the
computer. (See 2nd attached.) NOTE: The
higher the resistance, the
colder the reported temps. The ECT sensor
can & do fail, but it's also possible for an open wire between a good sensor and your computer to also cause the
misreporting of the engine coolant temperature. (!)
****
We had another forum member run into a similar starting issue, and together we worked through the problem until it was
solved. (
Truck won't start, need suggestions) Here's a list of replies where we were making troubleshooting progress:
* Reply #20 (Clear Flood mode - explains why truck will start if throttle held wide open)
* Reply #55 (Troubleshooting)
* Reply #57 (Factory Service Manual procedure)
* Reply #64 (
FIXED)
* Reply #71 (Resistance Reading Confirmation)
****
Let us know what you discover. If you are experiencing a similar failure with your TBI system, then the above should work for you.
If on the other hand your ECT resistance measurements match the table (cold & hot) -and- the wire between the sensor and your
computer has continuity, then we need to seriously consider getting a scan tool involved that will show you the live data that all the
sensors are reporting to your computer. And if you have any questions on the above, don't hesitate to ask for clarification.
Since your engine is running fine most of the time, you are close to the finish line. Hope this helps.
Happy Hunting --