One of my neighbors is a roofer. He replaced and sealed the flashing above my deck awning so it won't leak over the rainy, rainy winter. In exchange I'm working on his Blazer. It's a 92 with the 4.3 and TBI. It's throwing codes 42 and 45. It stalls and dies randomly but starts up afterward. Sometimes it was hard to start initially.

I started checking out the ignition system. None of the auto parts stores around me can check the Electronic Spark Control Module. The Ignition Control Module checked out OK after repeated testing. The coil was weak so I replaced it with a good one from my wrecked 94 Jimmy. The distributor cap and rotor were in bad shape so I replaced them with new ones. I also replaced the air cleaner while I was at it.

The truck starts and runs much better now but it still has the dying problem and codes 42 and 45 have returned after I cleared them. I looked at the O2 sensor output with my scanner and it looks like it's slow. It doesn't cover the range between 200mV and 800 mV as quickly as it should. Sometimes it doesn't oscillate at all.

What else should I check out? I don't have any experience with the Electronic Spark Control system or the TBI motors.

 

More than likely your getting the code 45 due to the code 42 ... which means you probably need to replace the electric guts of the distributor. Weak or erratic spark causes unburnt fuel to enter the exhaust, hence the code 45 - which is for a rich condition.

For a test, grab yours & try it on his. Make sure both vehicles are at TDCC ( rotor pointing at the #1 cylinder tower) and mark them on each unit so you can get them back in the same position. Then just line up your rotor to where the mark SHOULD be on your distributor when comparing it to the old one out of his vehicle. Drop it in & go for a test drive. If it runs great, then that's your problem.

A bit of work, but better than throwing expensive parts at it.

 

What guts are under the distributor other than the ignition control module? Is there a pickup coil?

Luckily I don't have to pull the distributor off my Blazer. I have a wrecked '94 Jimmy that would be more than happy to loan its distributor for the test.

 

Yeah that's what I meant - the module & the stator assembly.

Good deal on the spare! Makes life easier.

 

Bingo! I swapped the distributor from the Jimmy into my neighbor's Blazer and it fired right up with no problems. The Check Engine light never came on. Problem solved.

To celebrate I'm going to replace the Pitman arm on *MY* Blazer. I don't want it getting jealous.

Pitman arms come off these trucks really easily, right?

 

Good deal!

Ahhh ... pitman arms on S-series. Fun! Fun! Just so happens that I did this yesterday, along with the idler arm. Biggest pain was getting the sway bar back on - had to move it in order to get my 34 or 35mm socket on that nut there, after sliding the whole steering box forward.

Off to get what seems like a yearly front end alignment today ....

 

I got the Pitman arm on today. It took several hours and some assistance from my brother-in-law. The only difficult parts were cutting the cotter pin on the castellated nut and getting the Pitman arm off the steering gear. It was so stuck on that the impact wouldn't budge it. I had to take the steering gear out of the Blazer and put a breaker bar on the puller and a pry bar on the arm and put six foot pipes over each of them to get enough torque to turn the puller screw. It took my brother-in-law standing on one pipe and me putting my entire 240lbs on the other one to get it off but we did it.

Now off to the alignment shop...