1994 S10 Blazer 4.3L(Black smoke, rough idle, floods right away...?

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1994 S10 Blazer 4.3L(Black smoke, rough idle, floods right away...?

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Blazer >> Mechanical & Maintenance >> General Tech Help >> 1st Gen S-series (1983-1994) Tech >> 1994 S10 Blazer 4.3L(Black smoke, rough idle, floods right away...?

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1994 S10 Blazer 4.3L(Black smoke, rough idle, floods ri... - 10/26/2007 1:01:16 PM

CrashPro993

Posts: 15
Joined: 10/25/2007
Status: offline

Sorry to hassle you guys but I have an issue that is frustrating me to know end... Recently Purchased a 1994 S10 Blazer(Tahoe Package) 4WD with 4.3L Vortec.

It runs very rought at idle and smooths out in the higher RPM range.
Shoots black smoke out the exhaust constantly and leaves the grass on the ground black.
Strong fuel smell
Have to hold gas pedal all the way down to even get it to start (when it decides to.)
Exhaust is very load at both front doors, possible exhaust donut gaskets blown?

What Ive done thus far:

Changed Spark plugs, old ones were black and smelt like fuel of course.
Disconnected O2 sensor to set computer to default.
Found Coolant temp sensor on pass. side of block broke and replaced it.
Disconnected battery for 15 min and reconnected, same problem

Any Help would be greatly appreciated.

Post #: 1

RE: 1994 S10 Blazer 4.3L(Black smoke, rough idle, flood... - 10/26/2007 1:44:46 PM

swartlkk

Posts: 15292
Joined: 5/1/2005
From: Waterloo, NY
Status: online

Do you have a CPI motor (black plastic cover on top of the engine with orange VORTEC text) or the TBI motor (traditional round air cleaner on top of the motor)? I'm guessing CPI.

Start out by testing your fuel pressure. For the CPI, the fuel pressure should be 55-60psi with the key in the run position, engine off. After you turn the key off, the fuel pressure should not drop more than 10psi and should hold steady after the initial drop. If the fuel pressure drops down to nothing, you have an internal fuel leak. A new member recently went through this and posted some very good pictures of the actual problem, but I can't seem to find the post right now... Anyway, you can remove the plastic cover and then remove the round plastic device under the cover (the MTV valve) and have a peek down inside. If you see pooled fuel, you have an internal fuel leak. If you cannot get a good look through the hole, either use a mirror or remove the upper plenum. With the upper plenum off, you can pressurize the fuel system and really look for the leaks.

_____________________________

Kyle-

My Restoration Projects
Please Do Not PM for Tech Help

(in reply to CrashPro993)

Post #: 2

RE: 1994 S10 Blazer 4.3L(Black smoke, rough idle, flood... - 10/26/2007 2:08:47 PM

CrashPro993

Posts: 15
Joined: 10/25/2007
Status: offline

yeah its a CPI, Ill check that out tonight. So if theres and internal leak, what is it usually? Thanks for the help!

_____________________________

1994 S10 Blazer (Tahoe Package) 4WD 4DR 210,000 Miles.

Current Needs: Tires and time to install the goodies

(in reply to swartlkk)

Post #: 3

RE: 1994 S10 Blazer 4.3L(Black smoke, rough idle, flood... - 10/26/2007 6:30:42 PM

swartlkk

Posts: 15292
Joined: 5/1/2005
From: Waterloo, NY
Status: online

Usually on the CPI motor, it is a faulty FPR. From the sounds of it, you have an internal leak.

_____________________________

Kyle-

My Restoration Projects
Please Do Not PM for Tech Help

(in reply to CrashPro993)

Post #: 4

RE: 1994 S10 Blazer 4.3L(Black smoke, rough idle, flood... - 11/5/2007 7:40:39 AM

CrashPro993

Posts: 15
Joined: 10/25/2007
Status: offline

ordered and entire intake manifold with the the CPI unit, sensors, and all gaskets. Should have it this week and will be putting it on this weekend. Ill keep you updated, thanks again!

_____________________________

1994 S10 Blazer (Tahoe Package) 4WD 4DR 210,000 Miles.

Current Needs: Tires and time to install the goodies

(in reply to swartlkk)

Post #: 5

RE: 1994 S10 Blazer 4.3L(Black smoke, rough idle, flood... - 11/8/2007 2:32:53 PM

CrashPro993

Posts: 15
Joined: 10/25/2007
Status: offline

Found this post pertaining to my situation. Don't know the guys, but I'd like to thank them for the time and effor they put into it.

Thanks!

http://www.blazerforum.com/m_65358/tm.htm

_____________________________

1994 S10 Blazer (Tahoe Package) 4WD 4DR 210,000 Miles.

Current Needs: Tires and time to install the goodies

(in reply to CrashPro993)

Post #: 6