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06-02-2011, 10:01 AM #1
- Join Date
- Jun 2011
Please save my old school K-5 Blazer from the scrap yard.
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!!!!!!
06-02-2011, 10:18 AM #2
Sounds like cat is plugged, you say it "seems" O.K., how did you determine this?Adam
06-02-2011, 10:19 AM #3
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.
Last edited by 98Hotrod98; 06-02-2011 at 10:28 AM.
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06-02-2011, 11:11 AM #4
- Join Date
- Feb 2007
- Blog Entries
I'm also saying a plugged cat. Cut it out and see if that helps. If so, you solved your solution and performed a "performance" modChristopher
1991 Chevy Suburban 1/2 ton 2WD w/ chevy SBC 350-3/4 ton drivetrain upgrade w/4.10 gears 200K miles
2005 Saturn ION-2 Stock 277K miles
1982 Bronco, 1993 Bronco (sold), 1971 M35A2 Deuce and a Half
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06-02-2011, 01:15 PM #5
Welcome to the club. I have to agree with the others about the cat being plugged. If its the original cat I'm sure its plugged up some. Cut it out and see if your power comes back.
06-02-2011, 07:30 PM #6
- Join Date
- Mar 2010
Have someone stand on the gas pedal (in neutral) while you are standing by the exhaust. If there is a restriction the exhaust will sound like it is wheezing. If it is restricted it is not necessarily the cat, some of the older GM stuff used a double wall exhaust pipe. I have seen more than one collapse the liner and it will not show on the outside. It may piss off your neighbors but you can disconnect the pipes at the manifold connection and start it up. If the throttle response returns you are on the search for the restriction.
06-02-2011, 10:52 PM #7
sounds like you have multiple problems. first off if you have vac line problems and have had them for some time you very well could have been running it lean and burnt out your rings. also without you knowing your vac leaks very well could have gotten worse now causing it to run to lean. anytime that your having engine problems and you know yo have vac leaks then thats the first thing you need to fix. once you think you might have gotten them all start the engine, let it idle, and spray brake cleaner over every line, vac power items, ext. the brake cleaner will make the engine idle up noticeably with so much as a pin hole leak. vac line also have a tendency to stretch due to heat. use zip ties at every vac line connection to help ensure a tight seal. using brake cleaner along the intake and intake gaskets will also reveal if you have a cracked manifold and/or blown intake gaskets.
did you by chance check the oil and coolant to ensure there is no mixing of the 2 and also for fuel in the oil?
fuel pressure, did you check to make sure you have enough fuel pressure. its been some time since i have worked on carbureted engines but i think you want something like 8-13psi. check the pubs or you local chevy dealer to confirm that.
easy way to check for clogged cats is drop the exhaust and start it up. other than sounding bad and loud if it runs any better then you know it was your cats.
did you check your timing to make sure it still has a correct tune?
does it have a hei ignition? if so bench test the spark modulator to ensure proper function.
does it have any knocking and/or ticking sounds and if so from which location?
thats just some things i would have checked off the top of my head.
Last edited by mudpuppy; 06-02-2011 at 10:56 PM.94 sub 6inch lift 34inch bfg mt. massive rework project soon. the audio system hit 150.3db so now its time to rebuild and try for 155db. mudpuppy is also getting a new engine, rebuilt ifs, dual 500amp 15.1vdc alts, 5 5,000amp batts, ant the combined wattage with the new system should be close to 15,000watts. this is going to be a wild ride boy and girls.
06-02-2011, 11:12 PM #8
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.
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