Engine Miss in Blazer S10 4.3 Vortec

My 1993 S10 Blazer is running low speed rough idle. I replaced the rotor and cap, spark plugs (wires are 3 years old), cleaned the EGR valve and put a new gasket in the EGR valve.

Can anyone give me an idea of what can be causing the problem?

Reply to
packard
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Clean the throttle plate. Replace the fuel filter and check the fuel pressure.

Reply to
dahpater

Thank you. I cleaned the throttle plate. I will replace the fuel filter. How do I check the fuel pressure?

Reply to
packard

You will see a small shraeder valve behind the air plenum to the right of the distributor (right behind cyl #5 I think). You need a fuel pressure gauge to do this properly. I'm going to guess that it's either a bad fuel pump or pulsator OR the dreader fuel spider under the plenum. If you want a quick check, open the throttle plate and stick in a mini light and mirror - look for very clean, shiny spots to the left and right side. If you have gas smell and a clean spot to the left, you may be able to replace a fuel pressure regulator and be back in business. If the leak is on the right, you likely need new fuel inlet lines (aka, 'nut kit'). If it seems that it's leaking all over and you just want to do the job properly, get both the fuel spider and nut kit from either Linder Tech or an AC Delco dealer. The first step is to ensure that you're getting 58-62psi consistently with the key on engine off. It should drop to maybe 52psi when the engine is running. If that pressure doesn't hold for more than 10min-an hour, you have a leak in the fuel system that needs to be fixed. Can you smell fuel when exiting or entering the vehicle?

Thanks and let us know. I just went through this and I'm not in the clear after replacing the pump, fuel spider and nut kit. I also did the cap, rotor, wires, cleaned the EGA, IAC, MAP replaced, etc... Don't throw away money till you check your fuel pressure. Have the codes shown that cyl #1 is missing or is it random? If it's cyl#1, it's likely a leak on the fuel inlet side because fuel can leak down into the cyl easily on that side (in my experience).

Andrew.

in article snipped-for-privacy@q69g2000hsb.googlegroups.com, dahpater at snipped-for-privacy@yahoo.com wrote on 6/20/07 6:02 PM:

Reply to
AWN

All of the previous advice is dead on. I have my own story with a '93 lumina. I did all of those things or what is realtive on my car. Ended up being the Computer how ever. How to check, real scientific method of finding roughly where it is locate, possibly above passenger side wheel well, and giving a good thump in that area. It should kill the vehicle immediately. Also my experience was when I started having problems it would run stupid and sometimes run fine. Go to a GM dealer for a rebuild if that IS the case. You can get a new eprom chip and computer for almost half of what you can a computer from Autozone or where ever. Don't know if this will help but it is worth a try if your still in the "testing" phase and don't want to spend money you don't have to. Price for computer and eprom for the Lumina from GM $280, but after wasting $500 on things that were not necessary that's fairly cheap. Good luck.

Reply to
bsquared

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