Moore9729

I have been having trouble with my express van (2003 4.3L) for the past couple weeks. I have owned this truck for about 6-7 years and have had almost no trouble at all with it. I started it up one day to run an errand and pulled into the alley (not even 25 feet from where it was parked) and the engine shut off. I couldn’t get the engine to start again. It kept cranking but would not start up. I pushed the truck into the garage and started checking on things.

It was very cold outside so I thought maybe trouble with gas. I had at least half a tank of gas in it, but I dumped thermo aid in the tank. I let it sit in the warm garage for a couple hours and tried again when I returned, same problem. I decided to change the crankshaft sensor bc I’ve had that trouble with another vehicle. I installed a new sensor and cranked the engine for around a minute total and it started spitting and sputtering and kicked out quite a bit of smoke for about 5-10 seconds then ran smoothly for the rest of the day. I shut the truck off a few times and it started up just fine. I filled the tank with good gas and parked it for the night.

It ran fine like this for another couple days and then another morning I had the same problem, it didn’t want to start. I cranked and cranked and never got it to turn over. I ended up changing the cap and rotor. I made sure I had spark and tried again. Again, after about 30 seconds of cranking (in 6 second intervals) it started up. White smoke kicking out of the exhaust and then ran smooth. I had no more trouble for a couple days.

One morning I had the same problem and I tried checking fuel pressure. The pressure seemed low but I wasn’t too confident in the old gauge I had in the garage. I knew I had never changed the fuel filter so I changed that and then talked myself into just swapping the pump bc the fuel level sensor had gone out years ago. After replacing the fuel filter and pump I rechecked pressure, it was good (around 60 psi after prime) I cranked again for about a minute and almost gave up bc it wasn’t starting, then the engine started and ran rough for about 3 seconds then started running just fine. I ran it for the rest of the day with no problems.

The next morning I went to start and have no start condition again. I had checked for codes but cleared them before I wrote anything down. I remember two said oxy sensor, one code said something about fuel and theft deterrent. I’m hoping this one comes back so I can research that.

Now I am in the process of replacing the passlock sensor housing and the ignition lock cylinder and then relearning.

If anyone can help guide me into diagnosing the issue, or has any advice on what to check I would greatly appreciate it.

In short I have replaced cap, rotor, crank sensor and pigtail, fuel filter and fuel pump

Thanks!
Kyle

loopedr1

is it throwing any codes...i had the same problem with my 2003 express...but i had a crank sensor code...so i changed the sensor,,,,didnt fix it...turns out the harness at the front of the motor had rubbed on the passenger side head and made the problem intermittent......if you have codes check your harness,,,,,

Moore9729

Thanks for the reply,
Last night I changed the passlock sensor(part of the lock cylinder housing) and the lock cylinder. I had to do the relearn procedure for both keys. When I was done with the relearn on the second key the truck started up. I kept shutting it off and starting it, switching keys and didn't experience any issue at all. This morning I went out to start it up and no luck.

I just scanned for codes.
There is only one pending trouble code P0161 O2 sensor.
There is an anti-theft device code P1631 but I believe that showed up before I did the relearn procedure for the keys.

This van has 258,000 miles and I know we have never replaced the O2 sensors, I am not surprised to see that code.

I will check the harnesses up front for rubbing and let you know.