Truck Stalls But Fuel Injectors Keep Spraying?? Video Included

[19Silverado94]

So here’s my adventure so far

Just picked up a 94 Silverado 4WD. Wouldn’t start so I replaced the distributor, spark plugs, wires, and ignition coil. It started right up Figured I’d change the oil before trying to drive it home. Removed the oil drain plug and nothing came out poked a screwdriver in there and chocolate fudge started slowly coming out. Bottles and cans of oil, engine flush, and SeaFoam later now it’s coming out amber. Tried to drive it but it stumbles and stalls if I apply throttle. Also changed the IAC valve, both temperature sensors(manifold and head), both fuel injectors, all TB gaskets. I did a search on this forum and managed to pull codes 15, 22, 33, and 43(after replacing the Service Engine Soon bulb which was burnt).

15 - Engine Coolant Temperature Sensor Voltage Low
22 - Throttle Position Sensor Voltage Low
33 - Manifold Absolute Pressure Sensor Voltage High
43 - Electronic Spark Control/Knock Sensor

Both temperature sensors are new, I’m going to replace the MAP sensor today, new knock and throttle position sensors are on their way from RockAuto along with a new PCV valve, hose, and 180 degree thermostat. Other things to note are my PCV valve and throttle body were clogged with thick gunk. Soaked them in solvent while brushing, picking, and air blasting them until they were clean. My engine temperature on my gauge pegs out all the way to hot when I start the truck after replacing the sensors. Before the gauge never moved no matter how long the truck idled which led me to replace it. The SES light is constantly flashing when I start the truck. Anyone experience this and what did you do to fix these issues? Thanks in advance! I’m planning on doing a full restore on this truck, didn’t want it to end up in the crusher!

 

[19Silverado94]

Update: Replaced the MAP Sensor, cleaned 2 or 3 grounds on the engine manifold, Replaced Oil Pressure Switch(fuel pump comes on when I wiggle the connector though?), and disconnected the battery hoping to clear the codes. The only code that came back was Code 43. Replacing the Knock Sensor today. Also the Service Engine Soon light is no longer constantly flashing it just stays on solid. I shot the timing after replacing the Oil Pressure Switch since I had to remove the distributor. Truck stalled after idling for a few minutes. Fuel injectors were still spraying for some reason? Video link below.

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[19Silverado94]

Anyone?

 

[DerekTheGreat]

Welp, I'm firing from the hip here but if code 43 exists you may still have an issue with the ignition module or the knock sensor or the ESC module. That ESC(?) module on my '89 lives just in front of and to the left of the throttle body. The dizzy/ignition module is what fires the injectors, or at least determines when they should be fired. After looking at your pic it looks like someone has been in that truck extensively, judging by the electrical tape on the wires for the injectors. So perhaps someone did some weird things with the wiring or the injectors are stuck open. Maybe the ECM is suspect too,

Another thing which occurred to me is I once had code 43 pop up. Back with the old engine which had a burnt valve. I'd go to nail it and it'd spark knock for a second and then throw that code. This was with a new distributor & ignition module. All that stuff went on the new engine and I never saw the code again. Timing was set on both engines to 1 degree BTDC

 

[19Silverado94]

Welp, I'm firing from the hip here but if code 43 exists you may still have an issue with the ignition module or the knock sensor or the ESC module. That ESC(?) module on my '89 lives just in front of and to the left of the throttle body. The dizzy/ignition module is what fires the injectors, or at least determines when they should be fired. After looking at your pic it looks like someone has been in that truck extensively, judging by the electrical tape on the wires for the injectors. So perhaps someone did some weird things with the wiring or the injectors are stuck open. Maybe the ECM is suspect too,

Another thing which occurred to me is I once had code 43 pop up. Back with the old engine which had a burnt valve. I'd go to nail it and it'd spark knock for a second and then throw that code. This was with a new distributor & ignition module. All that stuff went on the new engine and I never saw the code again. Timing was set on both engines to 1 degree BTDC

I’ll take from the hip versus no shots fired at all lol The electrical tape on the fuel injector wiring is my doing, because there was no insulation on the wires within the Throttle Body. Wondered if the exposed wiring was what caused the injectors keep spraying after the truck stalls, but made no difference. Do you have a picture of the ESC Module? The ECM is next on my hit list. The following parts are new: Distributor, Cap & Rotor, Ignition Module, Ignition Coil, Spark Plugs, Spark Plug Wires, MAP Sensor, Coolant Temp Sensor(manifold), Coolant Temp Sender(head), Knock Sensor, IAC Valve, TPS, and Oil Pressure Switch at the top rear of the manifold. I read on the forum someone had similar issues and their reported fix was the alternator. I did have trouble starting the truck in the beginning and believed there was an electrical issue because of the symptoms so I’m going to replace the alternator anyway since I was going to do it next month anyway.

Also since I disconnected the battery cable for an hour after changing the sensors to see what codes remained. I now have only codes 34 and 43.

Your code 43 was due to a burnt valve? Intake or exhaust?

 

[RichLo]

Huh, that's a new one, is the key still in the run position when it does this or off?

 

[19Silverado94]

Huh, that's a new one, is the key still in the run position when it does this or off?

Yes, the key is in the run position still. I’ll start the truck, it will run for a few minutes when cold. Then the idle will start looking worse and worse until it stalls, then the fuel injectors keep spraying. I’ll record another video later.

 

[19Silverado94]

Replaced the alternator and the truck ran noticeably better. Will continue troubleshooting in the morning, just wanted to check in with that update. Also, does anyone know what this loose wire connector is for? Comes off the ignition coil harness I think.

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Shiny new alternator!

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[DerekTheGreat]

That connector is a tach lead. What I used when doing the moonies to needles swap. That ESC module went away or the location of which changed after a certain year. I know they were mounted right to that black plate in the photo of your engine bay. See that plate to the left of the throttle body, about 10" behind the A/C compressor? That's whereabouts mine lives, if not on that same plate. My MAP sensor is just behind that..

Aftermarket parts are crap, the ICM could still be suspect or there could be some wires mis matched or the ECM could be toasted. Off hand I remember reading in the manual that the ECM reads the pulses generated from the ICM to determine when to fire the injectors. It also uses MAP, TPS & engine RPM data to determine pulse width for the injectors. The only thing that controls them is the ECM.. A short to ground would essentially cause the injector(s) to burn up.. So If I'm remembering everything correctly the reason I suspect those components is the ECM "thinks" the engine is still running, as it's still firing the injectors. New one for me for sure..

I had a burnt exhaust valve. Verified by the paper towel by the exhaust trick. Truck always had a strange exhaust note, it "chuffed" every two seconds or so. Tailpipe tried to suck the paper towel up into it and that was the definitive test. RIP 350. However, I never had code 43 with the old dizzy and ICM. I ended up having to replace the thing when I went to change plugs, wires & cap to try and cure that rough idle caused by the dead cylinder (I didn't know it was dead at the time.) Truck wouldn't start after I touched the old dizzy and so new stuff went in. I don't remember what the timing was on the original engine, 0 or 1* maybe.. Anyway, new stuff went in, truck fired up and ran but now it was as if the thing went full advance on me when I got into the throttle, spark knock city. When it did that, bam, CEL was set and code 43 was the reason. CEL was always off when the truck was restarted. New used motor went in using all my ignition stuff and no issues with the ignition after that. With your truck though, is the CEL on at all times? If it is, maybe it's in "Limp home mode?"

 

[19Silverado94]

That connector is a tach lead. What I used when doing the moonies to needles swap. That ESC module went away or the location of which changed after a certain year. I know they were mounted right to that black plate in the photo of your engine bay. See that plate to the left of the throttle body, about 10" behind the A/C compressor? That's whereabouts mine lives, if not on that same plate. My MAP sensor is just behind that..

Aftermarket parts are crap, the ICM could still be suspect or there could be some wires mis matched or the ECM could be toasted. Off hand I remember reading in the manual that the ECM reads the pulses generated from the ICM to determine when to fire the injectors. It also uses MAP, TPS & engine RPM data to determine pulse width for the injectors. The only thing that controls them is the ECM.. A short to ground would essentially cause the injector(s) to burn up.. So If I'm remembering everything correctly the reason I suspect those components is the ECM "thinks" the engine is still running, as it's still firing the injectors. New one for me for sure..

I had a burnt exhaust valve. Verified by the paper towel by the exhaust trick. Truck always had a strange exhaust note, it "chuffed" every two seconds or so. Tailpipe tried to suck the paper towel up into it and that was the definitive test. RIP 350. However, I never had code 43 with the old dizzy and ICM. I ended up having to replace the thing when I went to change plugs, wires & cap to try and cure that rough idle caused by the dead cylinder (I didn't know it was dead at the time.) Truck wouldn't start after I touched the old dizzy and so new stuff went in. I don't remember what the timing was on the original engine, 0 or 1* maybe.. Anyway, new stuff went in, truck fired up and ran but now it was as if the thing went full advance on me when I got into the throttle, spark knock city. When it did that, bam, CEL was set and code 43 was the reason. CEL was always off when the truck was restarted. New used motor went in using all my ignition stuff and no issues with the ignition after that. With your truck though, is the CEL on at all times? If it is, maybe it's in "Limp home mode?"

That’s a relief. I was thinking an unplugged wire but couldn’t find the other part of it. I will have to do a search to find the location of my ESC module.

Well something I noticed last night night was the fuel pump continued to run last night even after I shut the ignition off. Injectors weren’t spraying. Fuel pump went off after I unplugged the Oil Pressure Switch at the top rear of the manifold so maybe there’s a fault in that circuit somewhere. I have a small fuel leak I’m going to try to get to today. Truck hasn’t stalled yet.

I hope not! No odd sounds coming from the exhaust. What are the symptoms of Limp Mode? Another issue I have with the truck is I have 1st, 2nd, and Reverse gears but no 3 or 4. I suspected the 3-4 clutch packs are burned along with their respective piston and am planning on rebuilding my 4L60E.