1989 blazer running real rich

I have 1989 full size blazer that is running very rich. I have done several things to this truck and i'am not sure when it went wrong. 1. Cut off exhust including converter. Replaced with a single 4" pipe.
2. Took entire dash board out of vehicle. Left factory computer in place. 3. Replaced ingnition with an msd box 6a and a blaster coil. 4. I have tried to "fool O2 sensor but it does not seem to make any differance. The truck is going to be a seldom streeter mainly mudder but i would still like it to be reliable and perform well.
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One thing that can cause these trucks to run super rich is if the temp sensor for the computer fails. When this happens, the computer reads the "temp" as something like -60F all the time and dumps lots of fuel when it really isn't needed.
Big Chris

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Would it do it in closed loop also?
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If the CTS had failed then it would not enter closed loop. I'd guess that you think your truck is entering closed loop? (I doubt it) Without a functioning O2 sensor or a functioning temp sensor the truck will not enter closed loop. But here we go...............
1: What codes? 2: What codes? 3: What codes? 4: What codes? 5: What codes? 6: Any codes?
http://www.syty.org/old/d&e-code14.html That should help you with the temp sensor....
If that isn't it; What is your fuel pressure? Attach a gauge, and turn the KEY on but not the ENGINE. It should jump up and stay there. If it drops off really fast I'd suspect a fuel diaphragm. In any case once you get the rich problem fixed you should put the O2 sensor back in, it will help with the power in your particular case - as you can't enter closed loop without a properly operating O2 and a "tricked" O2 can't help w/ your schimetric ratio AFAIK.
BTW: First try at a REAL diagnosis, don't rip me a new asshole if I'm wrong.... -- "Ignorance is preferable to error; and he is less remote from the truth who believes nothing, then he who believes what is a wrong." - Thomas Jefferson Formerly: KJ the Lonely Grease Monkey

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You're right on the money, GMC.
I'm curious why they put a 4" pipe in--- they're going to take a hellof a hit on low-end torque....

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The 4 inch pipe was used strickly for looks and sound. We adjusted the timing last night and got it to run a lot better. The MSD is helping to burn off a lot of the fuel. Last night the only thing we could not get it to do was go from idle to WOT.
How much low end will i loose with the big pipe?
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scrap the computer now that you've trashed everything else....... the 6a box bypasses the factory ignition module (at least it does with my Super HEI kit) obtain a` performance carburetor. your carb is computer controlled using a mixture control solenoid, none of sensors are working correctly now so give up trying to fool the system and do it right. heres the recipe for my Short-bed 4x4: SBC 4-bolt truck block with Dart Iron eagle 180 heads w/64cc chambers and 2.02/1.60 valves resting on .028" fel-pro head gasket. hooker comp hedders w/ 2.5" pipe blowing thru flowmaster series #40 mufflers edelbrock performer rpm air-gap manifold w/600cfm edelbrock carb (rejetted) comp extreme 4x4 cam 216/228@.050,.467/.480" lift Comp lifters, pushrods, guideplates and pro-magnum roller rockers and Proform gear drive. MSD 6AL Super HEI kit and 50ohm wires and the latest edition is a Halmeter AF-30 air/fuel ratio monitor (very trick unit) All the power is channeled thru a TH350/NP205 with ORD twin-stick shifter into custom driveshafts turning 32" all terrains thru 3.07 gears, i had 3.73's but hiway driving at 70+ was draining the fuel tank rapidly as well as scaring other drivers with the whine from the gear drive and (not so mellow) tone from the flowmasters. the rear diff is welded so driving on wet pavement is outta the question. the 205 was borrowed from a '82 Blazer and installed in the p/u with a Dana 44 frt axle using manual locking hubs which works very well with the Eaton limited slip unit She don't pull thru the mud........she flys over the top. Do it right the first time bro and lose the 4" pipe.
--
Mad Dog



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Where are you? I'd like to see the truck & take a ride... someday my Jimmy might compare!
-- "Ignorance is preferable to error; and he is less remote from the truth who believes nothing, then he who believes what is a wrong." - Thomas Jefferson Formerly: KJ the Lonely Grease Monkey

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Upstate New York
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Lower NH. poo....poo
-- "Ignorance is preferable to error; and he is less remote from the truth who believes nothing, then he who believes what is a wrong." - Thomas Jefferson Formerly: KJ the Lonely Grease Monkey

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Ocklawaha,Fl.......about 15 minutes south of SR40 on CR314A -- Mad Dog

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Even further!
-- "Ignorance is preferable to error; and he is less remote from the truth who believes nothing, then he who believes what is a wrong." - Thomas Jefferson Formerly: KJ the Lonely Grease Monkey

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He doesn't HAVE a carb for the computer to control. It's TBI.

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My bad, i should realized that being a '89 -- Mad Dog

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