# 99 blazer help



## bostonwindows30 (Jan 23, 2013)

I have a 99 blazer when at a stop it shakes bad, and on taking off feels like huge lose in power, it's not loud and I smell fuel once it drives it's okay but really rough????? Help????


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## bostonwindows30 (Jan 23, 2013)

I changed plugs, wires, cap, filters,etc happened while driving it yesterday shakes a wobbles


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## concretemasonry (Oct 10, 2006)

Since it is unstable even while idling, have you had it on a computer diagnosis to determine the basic problem?

If it runs well and checks out after the massive part replacement, then it comes down to transmission and running gear.I have similar vehicles (175,000 and 145,000 miles) and the are little noisy for a block or so, but seems to be air and short term temperature start up situation since they run perfectly once the wheels turn.

That engine is usually bullet-proof, so if it runs properly it comes down to controls and drive train.

Dick


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## bostonwindows30 (Jan 23, 2013)

At a stop sign it's shaking and ready to stall once it drives it's fine.. But taking off seems to beg very sluggish like there am exhaust leak but there isn't miss of power bad,,,


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## bostonwindows30 (Jan 23, 2013)

This has just happened had the vehicle for 5years


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## caveeagle (Jul 22, 2013)

Did you replace all the parts before, or after it started running badly?

It could be a combination of things. Motor mounts is the first thing that comes to mind when you mentioned bad vibration at a stop.


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## bostonwindows30 (Jan 23, 2013)

I did a full tune up, about 6 months ago haven't changed any parts..


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## bostonwindows30 (Jan 23, 2013)

But when it's in park the power very sluggish


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## caveeagle (Jul 22, 2013)

> I changed plugs, wires, cap, filters,etc happened while driving it yesterday shakes a wobbles


did you change the plugs, wires, cap filters etc..... before or after it started running badly??


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## bostonwindows30 (Jan 23, 2013)

Way before


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## caveeagle (Jul 22, 2013)

Sounds like a vacum leak. A bad PCV valve can let crank vent to outside giving you a gas smell. Can also contribute to vacum leakage.

I would still suspect bad motor mounts. Sometimes worn out motor mounts can go unnoticed until something else goes wrong. ...You develop a vacum leak (for example), causing the motor run a little rough, and you get all sorts of wicked vibrations.

Is this an auto or manual transmission?


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## bostonwindows30 (Jan 23, 2013)

Automatic


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## bostonwindows30 (Jan 23, 2013)

I changed valve few months back


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## caveeagle (Jul 22, 2013)

Here's what I would do:

a) double chec all vac / PCV lines for any cracks/breaks. 

b) spray carb cleaner around that area and the intake manifold gasket area. (while its running) if there is a vac leak, you will notice the engine idle change when it sucks up the carb/TB cleaner.

c) Pull the plugs to check for fouling or burnt plug that might cause a miss.

d) compression test.


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## bostonwindows30 (Jan 23, 2013)

Will do thanks I will keep up updated


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## bostonwindows30 (Jan 23, 2013)

Nope nothing worked even changed out some lines, changed PVC valve and plugs are good, don't know now!!!


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## caveeagle (Jul 22, 2013)

Does your car have the 4.3L v6?

I am sure you would have stated this..... 

Are there any 'check engine' or 'service' codes showing up? Are you getting good fuel pressure?

Have you given the intake / throttle body a good cleaning lately? It could be something with the fuel injectors getting clogged.

I dealt with an EFI saturn that had a bad idle mixture. It was causing a very high idle but that may be worth checking. I think it was called a IACV on the saturns (GM product) (longshot)

I know a compression test is not easy for most DIYers, but that will let you know if you are getting good compression on all cylinders.


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## bostonwindows30 (Jan 23, 2013)

Just found out, no compression on 5 and 6 I am thinking the valves went, bad news need another engine...,.


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## Bigplanz (Apr 10, 2009)

Check whether fuel is getting to the dead cylinders.


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## Duckweather (Mar 26, 2012)

bostonwindows30 said:


> Just found out, no compression on 5 and 6 I am thinking the valves went, bad news need another engine...,.


 Could be a blown head gasket. can you see if there is a lot of sludge built up inside valve covers? Sometimes the pushrods can get so gummed they can't move fast enough and get bounced off the rocker arms. FYI from my Army training a fuel system has only five "circuits", high, low, pump, float, choke. Even all the new sensors control one of these circuits. They are all controlled within the computer instead of individually, but if you know how each sensor is linked, you can narrow down a problem.


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## cjm94 (Sep 25, 2011)

Check fuel psi to see if it holds psi. The regulator is under the upper intake and are common to leak and flood out the back cylinders. The rings may just be washed out from gas. Compression will usually come back if you put a little oil down the plug hole after you fix the fuel leak.


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## bostonwindows30 (Jan 23, 2013)

I don't see no fuel leak


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## bostonwindows30 (Jan 23, 2013)

Just put regular oil down in the hole???


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## cjm94 (Sep 25, 2011)

It will be an internal leak you won't be able to see it. That's why you need a fuel psi gauge and see if it holds psi. And yes regular oil you don't need much. Put a little down the plug hole and the crank it over before installing the plug.


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## bostonwindows30 (Jan 23, 2013)

Okay will do thanks..


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## caveeagle (Jul 22, 2013)

I don't think you confirmed engine type. If you have the 4.3L v6, GM had a serious issue with their 98-2000 Fuel injection systems. It was like a "spider" system that actual dripped fuel into the intake runners. They were chronically bad and GM even offered a retro-fit kit to correct the problem.

Not sure if this is your problem, but your symtoms sound a lot like the issue I had with my 2000 Express van that had the 4.3L v6.


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## bostonwindows30 (Jan 23, 2013)

Yes it is the same engine, so what should I do??


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## cjm94 (Sep 25, 2011)

Star with testing fuel psi


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## caveeagle (Jul 22, 2013)

bostonwindows30 said:


> Yes it is the same engine, so what should I do??


Checking the Fuel PSI is a good start. Also start reading up on GM's Pre 2000 fuel injection issue. I paid a shop to repair the 4.3 that was in my full size van, but yours should be much easier to work on in a blazer.

I memory is correct, NAPA sold the kit, but it was a bit pricey. ($350 range, from memory). This was a common problem. Check to make sure your car was not already upgraded by a prior owner (probably not). If your on a tight budget, you might even try searching the junk yards for 97-00 GMs with the same 4.3. Many cars were retro-fitted by GM under warranty, and you might just find what you need, and get it dirt cheap. **you have to know what your looking for** 

I will try to post a link if I can find it.

*~*~*~*~*~*

Here is a good link with some information and pics of the conversion. They sell the conversion, but it seems a bit pricey to me. Check around on the net. Rock Auto, NAPA etc. (make sure this is your problem before shelling out the $$)

http://www.theautoshop.net/VortecMPFI.htm


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## caveeagle (Jul 22, 2013)

Here is another site with better pictures and a better price for the upgrade kit. (FYI)

http://www.fuelinjector.citymaker.com/Vortec_spider_fuel_injection_conversion.html


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## Duckweather (Mar 26, 2012)

bostonwindows30 said:


> Just found out, no compression on 5 and 6 I am thinking the valves went, bad news need another engine...,.


How did you determine the two cylinders had no compression? Seldom would there be NO compression without something like a hole in the piston or cylinder wall. A proper compression test is done with, charged battery, all plugs removed, throttle open, and same number of compression strokes, usually 3 or 4, dry then wet, (second try with a squirt of oil in each cylinder), Bad rings would show an increase pressure with the oil. Another test is put compressed air into each cylinder @tdc and listen for air at intake, exhaust, oil filler, and radiator. It will isolate a problem with rings, valves, or head gasket, if blown into water jacket or oil passage.


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## bostonwindows30 (Jan 23, 2013)

So you think the valves are not running because of that??


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## bostonwindows30 (Jan 23, 2013)

I took to a mechanic


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## Duckweather (Mar 26, 2012)

bostonwindows30 said:


> So you think the valves are not running because of that??


I cannot tell without being there. What I gave you is the orderly troublshooting procedure that will pinpoint or eliminate which component is the cause of compression loss. There may be other problems but you must eliminate this one if it is suspect. Nothing else will work properly without compression. Was a good compression gauge used to determine this?


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