Question about Chevrolet Blazer

1 Answer

Has fire fuel on new plugs will run about 3 days not very good. black smokes. Idel rough stumbles when you give it throtle seems better at 1500 rpm. When it wont start as soon as you turn the key off it will fire a plug and every so often engine off key on it will just fire the plugs about 6 times real quick. Shows o2 not enough switches multiple random missfire just recently showed system too rich. Showed one time o2 heater malfunction. It seems as if there is something shorting out causeing the injectors to pulse possibly other sylonoids. Key on engine off you can hear a high pitch noise. Tested ignition module vent sylonoids changed map sens checked vcm gnds sens gnds ect changed fuel pres regulator got worse does seem intermitent but getting worse.Primed furl rail no leaks. On scanner shows fuel trim to the negative short -31 % long -13 to-15 % 1500 rpm trim comes up some but at idle just negative symtoms everywhere this thing is driving me insane any advice please about to junk its sad is a very nice truck. Thanks

Posted by on

  • brakenit Dec 28, 2010

    98 chevy blazer 4.3 I have checked the EGR for carbon deposits new gasket checked didnt seem to have a sign of a short Checked MAF cleaned seems to show proper readings at idle and under load

  • brakenit Dec 30, 2010

    I did suspect the crank sensor because I did see a abnormal response on the timing seem to change an awful lot when I gave it throtle. Was also wondering about the cam sensor but was uncertain of the exact condition these faults could give. Very good point about the crank sensor intermitent short throwing the timing slightly. Will check this and let you know the results.



1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.


    An expert who has answered 1,000 questions.

  • Master
  • 1,098 Answers


You certainly done your home work on this fault so I sure you know what your talking about. I would be tempted to say this is an EGR fault or maybe combined with MAF sensor, can you give me the exact model and engine size and the year of the truck.



Posted on Dec 28, 2010

  • Dan Doherty
    Dan Doherty Dec 28, 2010

    Hmm, I'm not sure then, what about the crankshaft sensor?

  • Dan Doherty
    Dan Doherty Dec 28, 2010

    A dirty crank sensor may cause a intermitent short, which would throw the timing slightly and rough under 1500rpm, or it could be faulty.



1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

Rough idel, and black smoke

Is this correct, you have a silverado 1500 2004 that runs rough and black smoke out of exhaust, the check engine light on and how long has engine light been on?

Feb 03, 2013 | 2004 Chevrolet Silverado 1500 Crew Cab

1 Answer

Have a 90 Chevy 1500 with a 4.3 v6 and a 5 speed I the pickup was running fine left from work no problems then get off the interstate. And the running really rough I drove it to work the next day same...

Did you change the plugs in it, In That old of a truck depending on the miles on ot , If i had it i would be putting on a new cap and rotor, Not trying to clean it up, Allso it could be the control mudle breaking down, If it was never change, There could be a problem with the fuel (Injecters) Or throtle body.

Nov 09, 2012 | Cars & Trucks

1 Answer

1996 GMC jimmy rough idel and dieing when driving.

i have seen many strange things happen with the distrib cabs on these

Aug 22, 2012 | 1996 GMC Jimmy

1 Answer

Replaced plugs and coil pack on 2001 ford taurus now car will not start

You will need to figure out if you have spark to the plugs, and if not- if you have voltage to the coil to proceed.

Aug 04, 2012 | Ford Taurus Cars & Trucks

1 Answer

1990 mustang 5.0 runs ruff and spits and sputters and fluds out black smoke out exhaust .sometimes straightens out and runs good.what could be the problem?changed throtle positon sensor and still same

Hi,just to see if the spark is ok there is a light that fits inbetween the ht lead and spark plug so you can see if the spark fails why the car is running,hope this was some help.
you should be able to get one from your local car spare shop or on ebay,all the best hope you sort it.

Jul 20, 2017 | Cars & Trucks

1 Answer

Black smoke from exhaust, rough idle, black soot on plugs

signs of a bad fuel pressure regulator-- the vehicle will run rough, the engine will not start ( usually in the mornings,) many times engine starts but stalls shortly after starting. a bad regulator can result in fouled plugs. replacement is only cure. 1- black soot on plugs-2-black smoke from tailpipe-3- running rough-4- stalling, good-day! repost if need be.

Aug 10, 2011 | 1994 Suzuki Sidekick

1 Answer

Won't start unless spray fuel change fuel pump did'nt help when it starts idel rough throtle up slowly it go about 3000 rpm start trying to die if you floor it from idel it will die but spray fuel...

Then its got to be a problem with the fuel delivery. You need to check that you're getting fuel from the tank.

1) Does fuel get to the filter? If not, is there an airlock or debris in the fuel pipe
2) Does fuel get past the filter? - If not, replace the filter.
3) I'm not sure if you have a carb. or injectors, but one or more of the injectors could be blocked. If a carb., fuel inlet jet may be blocked.
4) Finally, is the air filter good and clean.

Jul 01, 2011 | 1990 Ford Bronco

1 Answer

1999 Buick Regal GSX won't stay running......

It's probably the mass airflow sensor and/or oxygen sensors.

Jun 18, 2009 | 1999 Buick Regal

1 Answer

Rough idle(200-300RPM)off idle runs great no white smoke

Have you changed your fast idle valve or air idel control valve I would change the air idle valve because it is the one with an electric sensor.

May 22, 2009 | 1990 Honda Prelude

Not finding what you are looking for?
Cars & Trucks Logo

Related Topics:

22 people viewed this question

Ask a Question

Usually answered in minutes!

Top Chevrolet Experts


Level 3 Expert

76164 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22156 Answers

Jeff Turcotte
Jeff Turcotte

Level 3 Expert

8273 Answers

Are you a Chevrolet Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides