1985 s10 2.8

i got 1985 s10 with a 2.8 thats not hitting on #4 cylinder i have done compession test on it its got 150 pounds tryied new plug and wire.i also sprayied a can b12 around intake to check for vacume leak and it does seem like its got one.

i got 1985 s10 with a 2.8 thats not hitting on #4 cylinder i have done compession test on it its got 150 pounds tryied new plug and wire.i also sprayied a can b12 around intake to check for vacume leak and it does seem like its got one.

Have you changed the cap and rotor? Put a plug on the wire and hold the plug to a ground or use a jumper cable and clip the plug with one end of the cable and the other to a good groung on the block. Have someone turn it over while you see if the plug has spark. If you don't have spark I will try to tell how to check the compression corectly.

Have you changed the cap and rotor? Put a plug on the wire and hold the plug to a ground or use a jumper cable and clip the plug with one end of the cable and the other to a good groung on the block. Have someone turn it over while you see if the plug has spark. If you don't have spark I will try to tell how to check the compression corectly.
i have tried putting a spark plug on the wire to see if its firing and it is firing.i havent changed the rotor or distibutor cap but i did check it and it doesnt have any cracks in it.

Have you changed the cap and rotor? Put a plug on the wire and hold the plug to a ground or use a jumper cable and clip the plug with one end of the cable and the other to a good groung on the block. Have someone turn it over while you see if the plug has spark. If you don't have spark I will try to tell how to check the compression corectly.


If you have a cracked cap you can burn a valve. AT 150 psi it sounds like you have compression. Leaky intake, Maybe. Did you run a compression test on the other cylinders? The minimum compression should not be less than 70% of the highest. A leaky intake will not make you loose compresion but would effect fuel to that cylinder. Have you pulled the rocker cover to see if a rocker has broke or come off?

If you have a cracked cap you can burn a valve. AT 150 psi it sounds like you have compression. Leaky intake, Maybe. Did you run a compression test on the other cylinders? The minimum compression should not be less than 70% of the highest. A leaky intake will not make you loose compresion but would effect fuel to that cylinder. Have you pulled the rocker cover to see if a rocker has broke or come off?
yes i have done compression on all cylinder and they all have around 150 pounds of compression i have took ther valve cover off to see valves were to tight.and none the rockers arms broke.