Weird stalling issue 2003 Chevrolet silverado 4.3L

MBertrand98 · December 24, 2016

Hello, I am new to the forum and currently seeking some guidance on my 2003 Silverado. I bought it a dew days ago for 500 bucks and drove it about 30 miles home with no issues. The reason why the seller was selling it so cheap was because it stalled on the highway and he had to limp it to the nearest shop. The shop couldn't figure anything out because the problem appeared as if it resolved itself (no check engine lights, motor starts with a turn of a key). So today I decided to fill it up with gas thinking maybe some water got in the fuel system or some easy scenario. Afterwards I start it up, pull out of the gas station, and it dies. It took a while for it to fire back up and it was definitely not happy so I limped it to the nearest side street where it stalled again and wouldn't start back up. Does anyone know what would cause this? Some possible things I can think of are: Evap Sensor purge valve, IAC? I'll give it the night and try to start it back up again and see what happens, any responses are much appreciated!

Info: 4.3L V6 246,000 miles, but one owner who took care of it, no check engine codes

burnt03 · December 24, 2016

Hello, I am new to the forum and currently seeking some guidance on my 2003 Silverado. I bought it a dew days ago for 500 bucks and drove it about 30 miles home with no issues. The reason why the seller was selling it so cheap was because it stalled on the highway and he had to limp it to the nearest shop. The shop couldn't figure anything out because the problem appeared as if it resolved itself (no check engine lights, motor starts with a turn of a key). So today I decided to fill it up with gas thinking maybe some water got in the fuel system or some easy scenario. Afterwards I start it up, pull out of the gas station, and it dies. It took a while for it to fire back up and it was definitely not happy so I limped it to the nearest side street where it stalled again and wouldn't start back up. Does anyone know what would cause this? Some possible things I can think of are: Evap Sensor purge valve, IAC? I'll give it the night and try to start it back up again and see what happens, any responses are much appreciated!

Info: 4.3L V6 246,000 miles, but one owner who took care of it, no check engine codes

This is probably a long shot but worth checking the easy stuff first... I was having the same issue with my Dodge Caravan . Turns out that my auto trans fluid was a bit low and causing it to lock up and stall the engine out. Topped up and it's been good for months. Good luck

muddkatt · December 24, 2016

First of all, forget the transmission issue mentioned above, no disrespect to burnt03.

Check fuel pressure at the rail, should be 50 PSI. Check for stored codes, not just a CEL on. The purge valve is a definite possibility if this only occurs after refueling. I "think" there is a in line fuel filter on the 03's, replace it and use either a Delco, or a Wix. Do NOT use a Fram or store brand.

Report what you find and we will help you figure it out.

NBSFan · December 24, 2016

Random stalling.....

My bet would be low fuel pressure due to a failing fuel pump. Reason being is you mentioned it stalled shut down on the previous owner and stalled after you fueled it up and that was 1 of the issues I had 2-3 weeks ago with my truck. If you check the fuel pressure on the fuel rail port it should be 50-55psi. Some pumps will still work 40psi-higher but you will notice things like stalling, poor acceleration, or if going up hills the engine might miss as though it's running out of gas. Sometimes you can extend the life with a fuel filter change but in most cases it's time tilt / remove the bed or drop the tank to R/R a new fuel pump with harness connector. Be sure to have your fuel tank checked for crudd in the bottom while the pump is out. I replaced mines with a Genuine AC Delco Fuel Pump & Filter.

MBertrand98 · December 25, 2016

golly yall respond fast, Ill check fuel pressure, throw a new filter on there, and check again, ill probably get to it on monday and keep yall posted, thanks again!

MBertrand98 · December 26, 2016

just an update, today I decided to try and start it and it started right up as if nothing ever happened which i think is just completely bizarre, anyway tomorrow ill pick up a fuel filter and pressure test the system

NBSFan · December 26, 2016

Random Stalls & No Starts = check your fuel pressure

MBertrand98 · December 26, 2016

Okay guys the results are in, I looked at the fuel filter and it looks almost new they must of already replaced it but I already bought one so I'll go ahead and put it in for my own sanity, so the pressure readings without the new filer are as follows: 43 PSI non running with fuel pump on, it jumps between 40 psi and 50 psi while Idling (the needle was pretty sporadic) and 45 psi when given a little throttle and needle wasn't sporadic, so from what I understand the pressure supposed to be 55-60 psi? Could the be a fuel regulator issue or a fuel pump?

PASASKMAN · December 26, 2016

Had the exact same issue as you, and took me all summer to figure out.

The Mass air flow sensor was the culprit. Put a new one in in October, and runs like a new truck. Hope that helps.

NBSFan · December 26, 2016

It's my understanding that fuel pressure needs to be at 50-55psi for the truck to run correctly. As I mentioned , it will run with less pressure but not 100% which I think explains your random issue. You can also check your fuel pressure regulator by removing the vac line. If fuel leaks out you found your pressure issue.

MBertrand98 · December 26, 2016

Okay so Im trying to find the fuel pressure regulator, it should be connected to the fuel rail I assume, the feed and return fuel lines seem to just go to the back of the motor and I can't really see back there, would it be on the back of the motor? whats the best way to get access to it? 4.3L V6

muddkatt · December 27, 2016

Okay guys the results are in, I looked at the fuel filter and it looks almost new they must of already replaced it but I already bought one so I'll go ahead and put it in for my own sanity, so the pressure readings without the new filer are as follows: 43 PSI non running with fuel pump on, it jumps between 40 psi and 50 psi while Idling (the needle was pretty sporadic) and 45 psi when given a little throttle and needle wasn't sporadic, so from what I understand the pressure supposed to be 55-60 psi? Could the be a fuel regulator issue or a fuel pump?

Fuel pump...do not buy anything other than a AC Delco pump or you will be doing it again real soon.

Jetroallen · June 7, 2019

I had the same problem last week. I fixed it yesterday. This is what I did...

I started at the Throttle position sensor ($100.00) and no change. It would still die at a light, or stop, or turn. I had to play the 2 foot pedal game. Then I tested my fuel pressure. 50 lbs is good enough. Then I removed the throttle body. Tons of carbon buildup. And I use alot of fuel additive/cleaner/octane booster and it was still bad. I removed the 3-10mm bolts, unplugged the right side of the 1/2" coolant line connected to the bottom of the body, and it slid out with some wiggle force. Use the correct spray (Throttle Body Cleaner) and scrub the crap out of it. Dont scratch it, its aluminum.

Repeat the steps to reassemble, and it should run great. Mine did and does. Good luck.