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1991 Blazer 4.3 cranks but wont start

 
 
 
 
  #1  
Old 07-30-2006, 05:43 PM
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Default 1991 Blazer 4.3 cranks but wont start

Hello...I'm brand new to the forum here and I hope some body can help me out. I have a 91 Blazer with a 4.3 TBI. For a while I noticed a lack of power. A few days ago it left me sitting at the side of the street. The engine had no power what so ever and wouldnt even make it up a hill. The engine would sputter along if you held the gas pedal to the floor. It would go a few feet and once again stall out. If I held the gas to the floor it would cranlk over and eventually start again. It ran with a very rough idle and almost stall. Eventually I had to tow it home. When I opened the hodd I found that a mouse had chewed a bunch of the hood insulation and made a huge nest inside of the air cleaner, between the housing and filter. It did not look like any debris made it past the air filter. After removing about 10 sizzled mice and all the garbage, I tried to start the engine...nothing. If I hold the gas all the way to the floor it will fire (poorly) but stalls after less the a second. I removed the fuel line and its getting fuel to the TBI. I had someone crank it over while I looked into the TBI... it does spray fuel when cranked over. I pulled the #1 plug wire and its getting a spark. I removed the dist. cap and aligned the rotor with the #1 position. I used a piece of coat hanger wire and felt the piston at what seemed like TDC, so I dont suspect a timing chain problem. Any ideas what the proble might be? I have never worked on anything with a TBI or ECM. I have always worked on carbs and older cars without computers etc. This thing really has me stumped.
 
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Old 07-30-2006, 07:32 PM
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Default RE: 1991 Blazer 4.3 cranks but wont start

If you're absolutely sure that you have SUFFICIENT Fuel and spark then only 2 things come to mind, either you have poor compression caused by worn components (Camshaft, rings etc..) or timing components, Or the catalytic converter is completely plugged up and the exhaust gasses cant get out of the cylinders. BUT first, with all those rodents, you really need to look that engine harness over real good for chewed wires. There are a lot of farms around here and I get rodent damage ALL the time, they love to chew wire insulation and often chew the wires clear in two.
 
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Old 07-30-2006, 09:47 PM
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Default RE: 1991 Blazer 4.3 cranks but wont start

I have experienced similar problems before on a different vehicle. What my problem was the fuel filter. Took it off, blew it out with compressed air and re-installed it. Car ran fine again. Then I bought a new filter and good as new. Just something to check.
 
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Old 07-30-2006, 11:48 PM
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Default RE: 1991 Blazer 4.3 cranks but wont start

wow thats a mess! did you check to see if any of the little critters are like clogging anything up? sounds gross but is that a possibility?? also did you check as stated that no more of the wires or vaccuum lines are damaged?
 
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Old 07-31-2006, 02:58 AM
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Default RE: 1991 Blazer 4.3 cranks but wont start

I did look for chewed wires and any critters that might be plugging something up. That was the first thing that came to mind. Just to be safe, I removed the TBI and made sure that there wasn't anything in the intake manifold. I'm confident that nothing made it past the air filter. I replaced the TBI to manifold gasket at that time as well as all my dry rotted vaccume hoses. The Blazer is kept on 11 acres of woods with about 30 freakin cats running around. I'm still amazed that any mouse could have even had the chance to breed in under those conditions, let alone climb into the air intake duct. I'm sure that the engine was getting practically no oxygen with the air cleaner blockage. Is it possible that this some how effected my ECM? Could it have fried it?
 
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Old 07-31-2006, 03:10 AM
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Default RE: 1991 Blazer 4.3 cranks but wont start

Naw, I don't think it would have fried the ECM. Have you tried disconnecting the batttery to clear the ECM. Although like posted above, it sounds more like a plugged cat, or plugged exhuast.

No doubt they made a nest in the intake, whats to say another family didn't move into the exhaust pipe?
 
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Old 07-31-2006, 03:14 AM
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Default RE: 1991 Blazer 4.3 cranks but wont start

I agree with Aquaholic (even tho he still hasn't posted a pic of his Caprice for me) , and I would suggest a plugged exhaust (catalytic converter).
If you don't want to drop the exhaust at the "Y" pipe, just pull out the oxygen sensor and fire up the engine. If you notice an improvement, then consider replacing the catalytic converter.
Keep us posted, there are lots of ideas in this forum.

Welcome to the forum.
 
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Old 07-31-2006, 03:30 AM
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Default RE: 1991 Blazer 4.3 cranks but wont start

Hmmm...Now I'm wondering if the cat just insn't blocked up as well. Is it possible that the rich fuel and no air condition could do that to the cat convertor? I'm thinking it would be unlikely that some fat critter got itself stuck in the exhaust pipe, but I'll try dropping the exhaust and see if its a blocked up cat. Getting back to the time I tried to drive it home, I had to keep my foot to the floor just to get it to move forward. The exhaust was making a really strange noise, similar to the time I had a blown carb to intake gasket. When I crank it over now, it will fire if you hold the pedal flat to the floor. It sounds like it wants to start and will fire but wont really start running. Oh and thinking maybe it had something to do with the ECM...I did disconnect the battery for a few minutes before hooking it back together.
 
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Old 09-16-2006, 02:25 AM
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Default RE: 1991 Blazer 4.3 cranks but wont start

I just wanted to post a follow up to my Blazer that wouldnt start. As many of you were thinking, it turned out to be the cat. I tried to remove the air sensor, but it was so rusted in place it wouldnt budge, even with torch applied heat. I ended up dropping the exhaust at the manifolds just enough that exhaust gas would be able to escape past the donut gaskets. With a freshly charged battery it started up but ran like crap. I dropped the Y-pipe and the cat and it turned over and ran. It ran terrible for the first few minutes. I had to give it a fair amount of gas just to keep it running. Lots of nasty black smoke poured from the manifolds. After a few minutes the smoke cleared and it was now idleing fairly decent...loud of course with no exhaust. When I dropped the cat it looked like a bomb had exploded inside of it. The honey comb material was blown into lots of soot covered chunks. It seems that without air, lots of unburnt fuel had been making its way into the cat until it came apart. The total repair with the cost of a direct replacement cat ran me just under $200. I replaced the O2 senser while I had it all apart. It runs pretty good now with lots of power. I now need to figure out why the "Service engine soon" light is staying on and perform a good tune up. It idles jut a little rough but aside of that its running real strong. Thanks to everyone for the advice. It was very helpful and right on the money.
 
 
 
 
 
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