GM Truck Club Forum banner

Please save my old school K-5 Blazer from the scrap yard.

985 Views 7 Replies 7 Participants Last post by  98Hotrod98
My 84 K-5 is giving me issues. It is barey idling in park or in gear. While in park, it doesn't respond to giving it gas like it should and when I put it in gear, it drives ok for about 20 feet then I have to give it more and more gas to keep it moving. It won't really accelerate at all. With the pedal all the way down on a flat road, I'm going 30 mph and I'm heaing a lot of popping sounds.

I replaced the fuel filter, plugs, cap, rotor, and wires. Fuel pump is fairly new, catalytic converter doesn't seem to be plugged. Is it a carburetor problem??? It was lacking power for about 2 months when climbing hills, but not this bad. Aside from the lacking power, this problem started all of a sudden one night.

The vacuum lines are a mess, but they are the same as they were when it was running good. HELP!!!!!!
1 - 2 of 8 Posts
first off, welcome to the club,

I might say your timing is way off as a first guess, do you have a timing light?

The fact that your getting popping sound would normally indicate your getting fuel, but either your not getting spark, or your getting spark at the wrong time. May also be a bad tank of gas if your living near any recent flood areas.
If its a fuel delivery issue then can you have somebody press the accelerator while you take a look at jets in your carb. First off you should make sure your getting an even fuel spray.

Vacuum line issues can cause a whole host of issues with idling and running, but i'm not to sure it should cause an issue like your facing. this can be checked with a vacuum gauge.

Just to be sure, did you actually test your spark plugs and make sure they are not getting a good spark prior to replacing everything? a spark plug tester is only a few bucks at auto parts store.
  • Like
Reactions: 1
When catalytic converters fail they normally clog up with debris and block the flow of exhaust gas from getting out of the system. this causes extreme performance problems. In the extreme cases it will even prevent the car from starting at all. Most of the time it acts like a governor and limits the engine RPM to a fast idle. So how do you check a catalytic converter without removing it from the car??

You can do a vacuum check at idle and then at 1500 RPM. If the vacuum is say 21 inches at idle and like 15 inches at 1500 then the cat is likely clogged. In a carbureted car you can remove the air cleaner and have someone hold a strong light near the intake of the carb. Then look across the top of the carb into the light and rev it up. If you see a cloud of fuel vapor pumping up and down sort of hovering over the carb then the cat is likely plugged.

Next, remove the oxygen sensor and start it up. The hole where the oxygen sensor was will relieve the back pressure and it should run a tad better. If so, then disconnect the exhaust pipe at the exhaust manifold and try it again. If it is a clogged cat it will scream like a banchee and rev up to its normal 4000 rpm.

Remember: Cats don't go bad for no reason, if you don't fix the reason, then you will be replacing the cat again soon.
See less See more
1 - 2 of 8 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.