T man
Junior Member
- Joined
- Sep 24, 2024
- Posts
- 6
- Reaction score
- 0
- Location
- SW Washington
- First Name
- Travis
- Truck Year
- 1987
- Truck Model
- V20 Suburban
- Engine Size
- 5.7 TBI 350
New member, 1st time posting. Hopefully I am not duplicating a previous thread, but I have not found one identical to my situation.
87 V20 suburban, TBI 350, TH400.
Went on a hunting trip last year, about 500 miles round trip. Did great getting there but on way back got stuck, replaced ignition control module in dist. and that fixed the problem (it was original and slightly rusted).
Got home, tried to fire it up a month or so later, wouldn't start. Fuel was dumping out of the injectors and out of the throttle bolt (that turns the blades, idk the part name), landing on the intake manifold. Replaced distributor, injectors, new gaskets for the TB, and ignition switch in the column. No more dumping fuel.
Here's the current problem. It will start up and idle nice for about 10 minutes or so then stall out. Every time. It will start right back up after that, then repeat the problem. It will not stall out if I unplug the tan/black wire in the driver engine bay area (vacuum advance I think?). However I don't want to run it around at base timing, I want it running right.
I have replaced: IAC, O2 sensor, MAP sensor, thermostat unit on front, ignition coil, all the vacuum lines I could see in the engine bay, PCV valve, fuel filter, I cleaned all grounds, checked fuel pressure it's at a steady 10 or 11 can't remember spec now but it was steady on the high end of spec pressure), and the previous owner had already deleted smog/EGR. I also checked TPS and oil pressure sending unit, those checked out. We also re-did intake manifold gaskets as there was a small leak in the back. Latest thing I've done is replace the TB, as there was a small leak in the side where the fuel was originally dripping out. I may have forgotten something but I think that's it.
In my mind it should have something to do with the vacuum advance system but I can't figure it out.
Vehicle is currently at shop for AC replacement and he is trying to diagnose it as well. Shop owner was a GM tech for 25 + years, he's seen a lot but is nearly at a loss.
Before someone says carb it, I likely will eventually, but would like to fix this first as it may still be a problem whether or not I stick a carb on it.
Any help greatly appreciated.
Edit - it was my mechanics idea to replace the TB because there was slop in the throttle (rod/bolt?) that controls the blades. He could manipulate a whistle sound by lightly moving it around, indicating a leak. Haven't heard back since.
Also have replaced spark plugs and wires.
87 V20 suburban, TBI 350, TH400.
Went on a hunting trip last year, about 500 miles round trip. Did great getting there but on way back got stuck, replaced ignition control module in dist. and that fixed the problem (it was original and slightly rusted).
Got home, tried to fire it up a month or so later, wouldn't start. Fuel was dumping out of the injectors and out of the throttle bolt (that turns the blades, idk the part name), landing on the intake manifold. Replaced distributor, injectors, new gaskets for the TB, and ignition switch in the column. No more dumping fuel.
Here's the current problem. It will start up and idle nice for about 10 minutes or so then stall out. Every time. It will start right back up after that, then repeat the problem. It will not stall out if I unplug the tan/black wire in the driver engine bay area (vacuum advance I think?). However I don't want to run it around at base timing, I want it running right.
I have replaced: IAC, O2 sensor, MAP sensor, thermostat unit on front, ignition coil, all the vacuum lines I could see in the engine bay, PCV valve, fuel filter, I cleaned all grounds, checked fuel pressure it's at a steady 10 or 11 can't remember spec now but it was steady on the high end of spec pressure), and the previous owner had already deleted smog/EGR. I also checked TPS and oil pressure sending unit, those checked out. We also re-did intake manifold gaskets as there was a small leak in the back. Latest thing I've done is replace the TB, as there was a small leak in the side where the fuel was originally dripping out. I may have forgotten something but I think that's it.
In my mind it should have something to do with the vacuum advance system but I can't figure it out.
Vehicle is currently at shop for AC replacement and he is trying to diagnose it as well. Shop owner was a GM tech for 25 + years, he's seen a lot but is nearly at a loss.
Before someone says carb it, I likely will eventually, but would like to fix this first as it may still be a problem whether or not I stick a carb on it.
Any help greatly appreciated.
Edit - it was my mechanics idea to replace the TB because there was slop in the throttle (rod/bolt?) that controls the blades. He could manipulate a whistle sound by lightly moving it around, indicating a leak. Haven't heard back since.
Also have replaced spark plugs and wires.
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