This one has had me scratching my head for 6 months. My ’89 Chevy weekender pickup stalls with no warning. Then it cranks fine but will not immediately restart – no sputtering, no nothin’! Wait 20 minutes and it starts right up and runs fine, just long enough to get back home. I haven’t driven it much lately, just enough to test it each time I throw another part at it. Same thing, every time – starts fine cold, drives fine for 20 minutes and surprise, complete stall out. Wait 20 minutes (after pushing it onto the shoulder) and it starts right up. I determined that something is shutting down fuel delivery by viewing the injectors in the no-start condition. They were not spraying fuel into the throttle body. Possibly heat related. The OBD-I system didn’t give me any helpful readout.

Went online and tracked down every related forum thread and YouTube, and then went to work locking, loading and shooting the “parts cannon”, going after what I thought were the most likely culprits first. Some were just shots in the dark.

· Fuel Pump

· Fuel Pump Relay (under hood)

· Fuel Filter

· New injectors and rebuild fuel pressure regulator

· Engine Coolant Temp Sensor

· Fuel pump oil pressure switch

· Ignition Coil

· Cap, rotor, spark plugs, spark plug wire set

· Remanufactured distributor with new pickup coil and ignition module

· MAP sensor

· Throttle position sensor

· O2 sensor

· EGR

· Starter (due to all the cranking!)

· Finally, a remanufactured Engine Management Computer (ECM) thinking that the electronics were overheating and shutting down the system.

Same symptoms returned every time. Great cold starts and power - actually runs better than ever with all the new parts - and then stall without warning during test runs. Open the hood to cool (20-30 minutes) and it restarts just fine and runs long enough to get me back to my garage.

While pondering my next move I noticed a couple of my neighbors working on an early 80’s Jag in the front yard. Actually, one was working and the other was sitting in a lawn chair, directing! I wandered over to share my misery and pick their brains about my situation. The guy sitting in the lawn chair almost immediately suggested that the rubber (actually nylon) section of the fuel lines from the filter forward to the Throttle Body must be deteriorating and constricting, or vapor locking when they get hot, especially the sections that run nearest the exhaust pipe. Now I hadn’t considered this since both supply and return lines appeared to have been replaced in the past, using braided stainless steel aftermarket versions. But it was worth a try!

I found a correct replacement set of braided stainless over Teflon tubing at “Lines To Go.com”. When I removed the supply/pressure line I was disappointed. I dried it off and blew air through, no problem. I even cut in half in several places to examine the inner tubing. Clear as a bell, no deterioration. Then I removed the return line. I could not blow air through!!! Examining the ends, I discovered the end that connects to the fuel tank line under the truck cab was completely blocked (rust or other buildup). See photo.

Plugged fuel return line from 4.3 TBI


After installing the new return line and adding a can of Sea-Foam to clean things up, all seems to be well and I’m keeping my fingers crossed. Several test runs in the hot Florida summer have been without incident.
I’m thinking that because of the plugged return line the fuel pressure built up and the under-hood and exhaust heat must have combined to create a vapor lock (boiling gas) condition which blocked fuel delivery until things cooled off. Not sure if one of the fuel system sensors tells the ECM to cut the fuel if there is too much back pressure in the system. Thanks to my neighbor for his quick diagnosis regarding fuel lines.

 

Glad you got it figured out - that’s quite a blockage!

FYI, there’s no fuel pressure related sensors on that system - it’s too old.

Those injectors rely on fuel flow to regulate temperature - the restriction could’ve been causing vapor lock but it’s also possible the lack of fuel led to the injectors overheating, which is why it seemed to start/run fine only when cold.

 

Thanks Gumby22. I've been taking it on short runs for a couple of weeks now. Still running fine.

 

Any update on how she is doing? Curious to see if you got a good fix. I am also experiencing a similar issue. Started with a backfire issue, progressed to a losing power issue with a restart, then to a shut down with no start. Let it sit and starts then dies as a bit. Replaced my EGR valve, checked my EGR Solenoid. Found out my timing was advanced by more than an inch.

 

Truck ran fine all summer and fall. Never had the stall problem again :-)