Hi all,

I had another crank/no-start today. This is the second since about New Years and first since replacing my fuel pump a little while ago. This time it happened at the pickup window for my pharmacy. Luckily it was not busy and I didn't block anyone. I need some ideas on what could be going on.

Symptoms:

• It sounded like there was ignition in the cylinders while cranking, but as soon as I turned the key back it would die.
• I noticed that the automatic headlamps and driving lights were on and stayed on even after taking out the key and getting out of the truck. I had to cycle using the key and put-on and release the parking brake to get them to go out. (I have auto headlight system since my truck was first delivered to Canada.)
• The above symptom made me think there was a flaw in the logic circuits of the BCM or ECM, so I got out my tools and disconnected the wire to the negative terminal to my battery. As soon as I reconnected it and got back it, the truck started. I took this as a strong correlation of the importance of the electrical system.
• As soon as I got home I looked for codes and the only one I found was a pending code P1035 which points to an O2 sensor. I suspect it was thrown because of the extra unburnt gas in the cylinders. I did get a whiff of the smell of gasoline when I first started it at the pharmacy. When I went back to double check the OBD reader before clearing the codes the P1035 code had reset. I had not started the truck again after getting home. I have a Vident i400 scanner that allowed me to look for all possible subsystem codes but I could not find any thrown codes or pending codes.

So, what could be the issue that caused this? Bad wiring harness? Issue with the parking brake DRL circuit? Loose connections?

As some of you know I replaced my fuel pump recently with a AC Delco unit and have put on over 700 miles since then. I also replaced the fuel pump relay last year.

Any thoughts or ideas of where to look or what to check would be greatly appreciated.

 

Dang. This must be a puzzler to people to not get any suggestions. LOL

If I learn more I'll let everyone know. For the time being I'm keeping an 5/16" battery terminal wrench in the glove box so I can easily try what I did before again.

 

Battery disconnect switch? But i know it's a bummer with the Blazer batteries with the side posts.

It really has me puzzled.
DRL on with key out? Does it have a timer function?
What about interior lights?
What about the control lights before and during cranking? (ABS, check engine, oil pressure)
What about the intensity of the headlights during cranking? (Do they go dim?)
OAT (outside air temp) very low? But then it would crank oddly and slowly.?

Looking forward to the solution of the puzzlement.

 

Thanks for the ideas.

It cranked well. I don't remember the lights going dim while cranking, but I was not looking for it either. I don't remember anything odd in the gauges. It was daytime so I didn't notice any odd behavior with the interior lights. It is equipped with the Retained Accessory Power option.

If it happens again, I'll be looking more closely at all those ideas.

 

My negative terminal comes loose ever so slightly, I will cause a no start symptom after running and parking on short trips. I purposely carry a 5/16 battery terminal wrench on the driver door because it happens frequently. I assumed the battery terminal threads were shot and after replacing the battery same thing. I'm thinking of getting a crushable washer to give the stud preload.

 

So I had another crank/no-start a two days ago. I let it sit overnight and it still didn't start even after disconnecting the negative terminal of the battery.

For some context, I was close to E on my gas gauge parked on my slightly sloping driveway with the truck pointing downhill when it woukd not start. If I remember correctly, the actual reading on the gauge was just a needle's width above E when parked on the level and about a needle's width below E when parked facing downhill on my driveway.

I was able to get it started by putting a gallon of gas on it.

For at least this specific case, I suspect my new pump and level mechanism is more sensitive than the old one.

I then checked the fuel consumption and I had used 13.5 gallons, not the 12.0 I had expected.

I'll keep updating this thread until I figure this out.

P.S. I too bought one of those specialty battery post ratchet wrenches too!

 

That "sounds" typical for a sticking relay armature, AKA fuel pump relay in glove compartment. They're stamped thin metal with lots of friction, they can hang up, or stick in between.

Also, bad ignition switch. They run out of grease, the contact wear and get glumped up, and little bits of plastic can break off inside (in my 78 Blazer). Turning the key forward to Start engages both ignition and starter solenoid contacts in the ignition switch. Maybe the ignition contact is bad? A voltmeter on the power to the ICM would show voltage missing or low. BTW, there MUST be 14.x volts on that ICM at the distributor or it means weak/missing/ intermittent spark.

If the Electronics are doing strange things, disconnecting the battery will reset it. Its "possible" theres a bad alternator diode or connection putting AC on the electrical system, check that by turnign on the AM radio and listening for alternator whine. That ones WAY out in the weeds, but a real PITA to find.

 

For what it's worth, my Sonoma behaves similarly. The top 3/4 of the tank of fuel it starts immediately. The bottom 1/4 of the tank it will crank longer than expected, and if it's in the bottom 1/8th, (not all the way onto E) it will sometimes not start unless I prime the pump 2-3 times first. This is a newer behaviour too. A few years ago the gauge would have to be all the way below the red line before it wouldn't start, but now it can happen as soon as it gets close to the red.

For me, I prefer filling my tank if I get below 1/3, so it's rarely an issue, and I just haven't had the motivation to chase it further.

 

Thanks for the ideas.

I haven't had any more issues with it not starting but I also made sure to not park it with its nose pointing downhill when it got close to E.