94 blazer rough idle and gas smell

[koblazer]

i have a 1994 s-10 blazer with a rough idle and gas smell it sounds kind of like one cylinder is not firing or something. I was told by my mechanic that the CPI was the problem, i bought the part and put it in myself. once everything was back in i started it and same problem. I also checked the egr because i read in one of these threads that that could be explain the rough idle and the gas smell. any ideas what could be the problem?

[Chevy Maros]

I had that problem at one point with my 94. I installed a new spider injector CPI because a couple of the spiders lines were chaffed from rubbing things inside the intake, but before I re-installed the upper manifold I checked for leaks by putting fuel pressure through the system by turning the key to the on position, Not starting it, just turning it to on to get the fuel pump on. When I did that wouldn't you know there was a leak from the pressure line that comes in through the upper manifold. As with the spiders lines the pressure line was chaffed and had sprung a leak that was worse than the spider lines. So I went and got the pressure, return line and nut kit set from the dealer, cost me like 50 bucks, and after I replaced the wet spark plugs and changed the oil to get some fresh gasoline-free oil in the engine, it ran smooth.

So you might want to check those lines with the upper manifold off by applying fuel pressure, good luck man.

[koblazer]

ya i read in the free repair guide from autozone.com to pressurize the fuel lines and there were no leaks.

[koblazer]

also, im trying to take the spark plugs out to check them, but i am having the worst time taking the wire off the closest drivers side plug. it seems like the wire is attached directly to the spark plug

[Will Help]

Plugged fuel vapor canister can give similar problems especially the gas smell.

[koblazer]

where do you find this fuel vapor canister and what does it look like?

[JIMMY92w]

Its black and the size of a can of ground coffee beans. It's found on the drivers side, very front of engine bay, below the air filter, and lower then the head light. Remove air filter box for access.

[Will Help]

You may have to twist the boot as the heat of the engine tends to make them stick to the plug. If they are hard to reach, you can use a pair of needle nose pliers to carefully twist the boot. They also make a boot puller available at most parts stores. Use silicone boot lube to prevent this in the future.

[koblazer]

ya i got it out. thanks. so i replaced the spark plugs and it still sounds like a cylinder isn't firing. i checked them all and the are all sparking fine. no clue what to check now

[Will Help]

Next step I would take is to check compression on each cylinder. If you have a burnt exhaust valve/s you can be loosing power in that/those affected cylinders on the power stroke and also be feeding exhaust gas pressures back into the manifold through the intake stroke resulting in gas vapor blowing out of the intake manifold. When you check it, no cylinder should be 15 lbs or more less than any other cylinder and no cylinder should be less than 100 lbs.

Also encountered this one time on a 94 Mercury Lynx with only 45,000 miles. The cat self destructed and plugged the muffler. Gas was actually blowing up and out of the throttle body at idle and the engine ran terrible with about a 60% reduction in fuel mileage. Changed the cat and muffler, everything was fine again.