Won’t restart

[phantom 309]

I was able to apply the clear flood procedure and it will not start. Strong smell of fuel under the hood. Ad soon as I removed the injector leads it started right up.

well maybe you are not pressing the throttle on the floor and holding it down while you crank the engine over? Because the ecm cuts power completely to the injectors when that squence is initiated,. if your injectors are still spraying i think u may have either a throttle cable not pull the linkeage to wot,. or u have ecm glitch

 

[PlayingWithTBI]

if your injectors are still spraying i think u may have either a throttle cable not pull the linkeage to wot,. or u have ecm glitch

Or - you have a problem with your TPS too. The CTS and TPS share the same ground.

 

[Bluetieguy53]

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 --

Hey guys, finally got back to everyone that was helping me with my starting problem. I did the clear flood procedure and at first as I mentioned it wouldn’t start. I tried it after another drive and it started after clearing the fuel. Installed a genuine GM etc and the problem still persists. I have tried to find an old 1 diagnostics meter but it’s like finding hens teeth. I will share my tps readings are .50 at idle and 4.36 at wot. Other than my starting issue it still runs great. I appreciate any input.

 

[Bluetieguy53]

well maybe you are not pressing the throttle on the floor and holding it down while you crank the engine over? Because the ecm cuts power completely to the injectors when that squence is initiated,. if your injectors are still spraying i think u may have either a throttle cable not pull the linkeage to wot,. or u have ecm glitch

Phantom 309 I really appreciate your help. I posted on Road Trip just now and share this with you. My tps reading is .50 at idle and 4.36 at WOT.

 

[chris032188]

So just to post - I had the same issue, and even with the clear flood procedure it wouldnt always start. It usually eventually would if i did it and let it crank for a while, then even after it started it ran like ****. For the 20 bucks - I really would swap the coolant to ECU sensor, and inspect the wiring. I swapped sensor, waS still having issue then when I plugged it into a scanner I seen that it was still being read at -40, once I redid the wiring it fired right up.

 

[Scooterwrench]

Or - you have a problem with your TPS too. The CTS and TPS share the same ground.

Yup,that one up there connected to one of the thermostat housing bolts that always turns green from corrosion. Check that ground and if it is corroded up take it off and clean it then move it over to the right front intake manifold bolt where the ground cable from the battery lives,better ground in a drier place.

 

[Bluetieguy53]

So just to post - I had the same issue, and even with the clear flood procedure it wouldnt always start. It usually eventually would if i did it and let it crank for a while, then even after it started it ran like ****. For the 20 bucks - I really would swap the coolant to ECU sensor, and inspect the wiring. I swapped sensor, waS still having issue then when I plugged it into a scanner I seen that it was still being read at -40, once I redid the wiring it fired right up.

Thanks chis032188. I've installed the new sensor. My next ting is to check the wiring.

 

[chris032188]

If you were NJ I'd give ya my scanner to try and figure it out. Might be worth scouring marketplace for an older snap on. I picked up snap on Modi's for like 150. People lost these older scanners for alot but usually will take less. I messaged everyone who had one up for a month or more.

 

[Scooterwrench]

If all else fails buy an ALDL cord and download TunerPro RT. It's probably the best OBD1 scanner available now. TunerPro is free with a voluntary registration fee and the cord is about $60

 

[Bluetieguy53]

If you were NJ I'd give ya my scanner to try and figure it out. Might be worth scouring marketplace for an older snap on. I picked up snap on Modi's for like 150. People lost these older scanners for alot but usually will take less. I messaged everyone who had one up for a month or more.

Thanks for the info. It's worth getting one. My plan is to give it to my grandson as a first vehicle. He likes old trucks.