Hi Guys, this is my first post but I've been checking your posts for a few weeks to see if anyone else has a problem like mine, and here it is. I have a 2000 S10 blazer, 4.3 engine and CSEFI. It has 150K miles on it and I keep it in good condition. About 6 months ago it started missing under load. I changed the plugs, it didn't help. Changed the cap, rotor, and wires, still misses. Took it to a shop to get any codes that it might have stored, there were none, service engine light has never come on. While there, the mechanic noticed a grey spot on the coil where it had been arking off on the plates that suround the center part of the coil. New coil and it ran great for about a month, then the same thing. Coil was under warenty,got another Delco coil and cleaned the battery connections and any engine to body grounds I could find. Ran good for two weeks and then it started missing again. Another coil and a new coil pick up in the distributor and had the ICM checked, the shop said the ICM was good. The last coil I put on, about three weeks ago has died completely, it won't even start now. All the new parts other than the coil pick up are AC Delco. I still think it's a ground problem but I don't know where to look. Any help would be greatly appreciated, thanks, S.

 

defitly sounds like a ground issue that is shorting out the coils, have you noticed any fuses being blown at all, even ones that are not related to the problem? i'd start back at the starter and work my way back to the engine and then check at the alternator.

 

I've checked the fuses several times and have never had to replace any, the only electrical issue I've ever had is the ABS and parking brake lights in the instrument cluster sometimes comes on a few minutes after startup and stays on untill it's turned off. The battery and alt. was replaced about a year ago. When you said start at the starter and check back to the engine and then the alternator, do you mean the positive wiring? I forgot to mention, I installed an additional ground wire from the engine to the body but that didn't help. Thanks, S.

 

what about on the coils, yes i'd check even the positive coming back(but odds of that causing a direct short aren't very likely), check where the coils are and the surronding area to see if any of the wires off the coil are frayed causing a short. also if you get your hands on a scan tool see if it gives you a P0338, this will not set off a service engine light.

 

Hey Blaze, this engine has only one coil, its the enhanced distributor ignition. Yep I checked the power to the coil, wiggeled it around with the meter hooked up and voltage never faltered, no ark marks on the pigtail and dosen't look like it's been hot. I tried to crank it yesterday morning and it didn't. Put a new coil on it and it fired right up. This morning I drove it to an O'Reilly's up the street and talked to a freind about the crankshaft position sensor,I can't find a wiring diagram on the ignition circut to safely check anything. Took it to a little garage and had the scanner put on it again. It didn't show any codes, only missfire on every cylinder, We test drove it, went up a little mountain here and it didn't miss once. When we got back to his shop we talked a few minutes and when I tried to start it, it wouldn't. Checked fuel pressure and had none, The new fuel pump is junk,3 weeks old. The mecanic told me he thought it was a fuel pressure issue all along, but he can't explain why it stopped missing after I changed the coils. My Mom broke her hip today (she's 83) so it may be a few days before I get another fuel pump in it. I'm like you though, I think it might be the CPS, when I get her jacked up I'll check the sensor and the wiring. Thanks for your help, I'll let you know what I find. 3 AM are ya workin nites or some kinda insomneack?

 

must be a time change thing cause it was like 11 at night here. yeah it sounds like the cps is bad or the wire from it is faulty. if you have a misfire on every single cylinder it is gonna be a part that would effect all of the pistons. which the cps would determine the position of the crank which if it was faulty would cause a misfire. if a cps looks to pricey new you could probably pull one off a junker. just let me know what you find so i can help you out

 

Hey Blaze, did you think I'd just given up? I've tried to make two posts over the past week or so and when I hit the submit key it goes to a page and says I'm not logged on and lost everything I had typed. What's that all about? I was logged in or it wouldn't go to the reply link. Anyway, my not starting problem was not the fuel pump, I returned the Airtex and paid an additional $117.00 for a Delphi, is that the same as a Delco? When I put it in and tried to start it the pump never came on. Pulled it back out and checked for voltage and ground and had both. Hooked 12 volts to the pump with the tank out of the car and it ran, had my Dad turn the key on with the voltmeter on the wires and it showed 11.8 volts. I thought I had a short in the grey power or the black ground wires.I pulled the harness from the tank to the underhood fuse/relay box and checked the wiring, the only thing I found was in a connector at the rear of the truck that ties 4 ground wires together that had some corrosion on the ground pins, the connector also ties the tail lights and something else together but all that looked OK. I cut the ground wires off, twisted them together and soldered them. Put the tank back in and it cranked, several times, pulled it back in my driveway and shut it off. The next day it would not start, the fuel pump is not coming on. All the fuses looked good but I changed them anyway, switched out the F/P relay, checked the grounds at the lower raditor support that ( I think ) grounds the ECM and it was good. I unpluged the complete harness at the fuse/relay box and the ECM, all the plugins and the pins looked good, I cleaned everything with contact cleaner,applied a little dielectric grease and put it back together. It cranked right up but has a miss and twice when I slowed down with my foot off the gas pedal it died. When I got back home and shut it off it would not start, the fuel pump is not coming on, could this be an ECM problem? I've checked everything I can think of. I checked where the relay plugs in and it's good, battery voltage constant on one pin, voltage for 2 seconds when the key is turned on to fire the relay, a ground and the feed for the pump. I may not have had a coil problem after all, might have been the fule pump shutting off. I'm lost at this point, any help would be appreciated, S.

 

i would try a fuel pressure test to varify the pump is producing the right amount of pressure. you said it will not start back up when you shut it off. so when it sits overnight or will it not start immediatley after you shut it down?

 

Sometimes it will restart after a few minutes, sometimes a few hours, overnight, or after a day, theres no pattern. When it dosen't start it's because the fuel pump is not comming on at all. Any time you turn the switch on and can hear the fuel pump running, it cranks and runs. If you can't hear the pump, it fails to crank. I've checked everything from the EMC to the pump, grounds, wiring, relay, fuses, anything that I could think of that might cause the pump to lose power. Is there anything ( other than the EMC ) that controls fule pump power, or that might cause it to lose power? I haven't checked the pressure on this pump, it cranks and runs good when it runs, for some reason it just loses current sometimes. I'm thinking it might be the ECM, I'm stumpped at this point. Any advice would be appreciated, S.

 

if your pump checks out ok, the next thing i would check would be your ignition switch. kyle has some info on his sig. i'll see if i can find it https://blazerforum.com/forum/article-submissions-discussions-47/anatomy-ignition-switch-33465/