Failed Engine/Cyl Compression Test??, Unplugged Fuses & Impala.... :( - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 12-05-2015, 10:23 AM   #1
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Angry Failed Engine/Cyl Compression Test??, Unplugged Fuses & Impala.... :(

Hello Everyone, I come to You again My Brothers in the Name Of GM-&-The Chevy-&-The-3800-Series. This time, My problem is trying to figure out if I did something wrong, Or Something is actually wrong.. ?

I went to do a compression test on My car ['05 Impala 3.8], after completing the test, car won't start back up, It cranks and cranks but won't start. Before I started the test, I did unplugged some fuses in the fuse box under the Hood in an attempt to Disable the Fuel and Ignition. I UNPLUGGED 4 FUSE(*) THE ONES THAT READ "FUEL PUMP", "FUEL INJ", "F/PMP RLY" AND "IGN SW" [BUT WHEN I UNPLIGGED THE "IGN SW" MY RADIO WENT OFF - Now I don't know if this is normal or not?], But I Immediately plugged it back in. Could I have unplugged one too many fuses? could I Messed up something? Maybe the Fuel System/Fuel Pump? Now I Know I shouldn't have went unplugging all these fuses.. But I did so because, When I changed My Injector, I really had a hard time Unplugging the connectors, That'* why I thought It would've cut Me some slacks to Just unplug the Fuse. I actually saw in some Youtube videos that The Fuel Injector Fuses/Relays Could be unplugged instead of Unplugging them directly from the Injectors - Guess I shouldn't have went that route]

I initially though maybe I have to let it regain consciousness? Since the components were disoriented a little bit after unplugging the Ignition Switch. But I let it sit for 2 Hrs, Went back and tried to start it again & to no avail, Same Crank But no Start issue. Is there a Procedure that I needed to follow? or Is something really wrong now?

Let Me add, when I turn the key to ignition, I still hear the Fuel pump priming, But may not be delivering fuel to the engine? Because like I said, It Cranks and Cranks, But wont Start. At one point I got so frustrated and Cranked it so much [Like more than 7 Secs] that a ball of smoke puffed through the back of the engine, Just in front of the Firewall Behind the Alternator. So I'm thinking I must've messed up something else there?

So where do I go from here? What diagnostic Procedure do I follow?

Someone Please Help!!!!.

Thanks in Advance.
But
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Old 12-05-2015, 03:24 PM   #2
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Had you come here first and asked questions before doing all this work, you could have avoided headaches.

Did you know that you don't have to pull fuses to disable the engine from starting? Did you know all you have to do is hold the accelerator to the floor, then crank the engine? This is called, "clear flood mode". The computer sees the 100% throttle, and shuts off the injectors. But you must have the throttle at the floor before powering on.

You must retrace the steps you took when pulling fuses. Reconfirm you put them back in the original places.
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Old 12-06-2015, 11:24 AM   #3
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Had you come here first and asked questions before doing all this work, you could have avoided headaches.

Did you know that you don't have to pull fuses to disable the engine from starting? Did you know all you have to do is hold the accelerator to the floor, then crank the engine? This is called, "clear flood mode". The computer sees the 100% throttle, and shuts off the injectors. But you must have the throttle at the floor before powering on.

You must retrace the steps you took when pulling fuses. Reconfirm you put them back in the original places.
I Guess I Should've Came here 1st. I didn't know about holding down the Throttle, I'm gonna Try that with My Bonneville and see if holding down the Throttle will prevent the car from starting. But Yes, I did plug everything back into their original spots, Only unplugged the "FUEL PUMP", "FUEL INJ", "F/PMP RLY" AND "IGN SW" I didn't even take them far, I just tapped them right next to where I unplugged it from, so I don't forget where they go into, I'm more than confident that I plugged everything back where they belong.

Since the car is cranking like its gonna start, but wont, I'm thinking somehow someway fuel is not being delivered to the cylinders? What do You think?

Also, I was talking to someone yesterday & He told Me, that maybe one of the The Relays Might've went bad, since I pulled them while the key was in 'ON" position [Since I was Playing Music in the Car while I was doing this - Probably a dumb thing to do, But I definitely learnt My lesson] So doing so might've hurt one/more of the Relays. What do You think?

Thanks.
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Old 12-06-2015, 12:13 PM   #4
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Engines need 3 things to run.
1. Air
2. Fuel
3. Spark

We already know the engine is getting air, maybe getting fuel, but you do hear the pump prime, but are you getting spark and fuel into the cylinders?

One way to test the fuel/spark is to remove the intake duct off the throttle body and squirt a tad bit of carb cleaner into the intake while the engine is being cranked over. If it attempts to run, you now know you have spark. Now you need to find out why you are not getting fuel into the cylinders.
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Old 12-06-2015, 04:46 PM   #5
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When I did my compression test I just disconnected the ICM, but I was removing all of that anyway to do the UIM/LIM job..
Clear Flood mode is quicker for just compression testing.

Just curious but how were your numbers on the compression?
Did you let the engine run for just a minute or two, enough to get slightly warm, then remove all plugs, then test for compression?
I ask because it is best to do on a engine that is warm, but not hot, you do not want to burn your self from the exhaust manifolds when removing the plugs.

Also a note that you don't learn while watching most videos, let the engine crank until you see the compression tester stop gaining pressure, don;t give it 5 cranks and stop.

With that said try what Mike suggested, and let us know what happens.

Oh yea, the radio went off because it was tied to the ignition fuse, that is so the radio does not stay on once you cut the car off, and remove the key.
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Old 12-07-2015, 12:44 PM   #6
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Cool Good Info.

Quote:
Originally Posted by Mike View Post
Engines need 3 things to run.
1. Air
2. Fuel
3. Spark

We already know the engine is getting air, maybe getting fuel, but you do hear the pump prime, but are you getting spark and fuel into the cylinders?

One way to test the fuel/spark is to remove the intake duct off the throttle body and squirt a tad bit of carb cleaner into the intake while the engine is being cranked over. If it attempts to run, you now know you have spark. Now you need to find out why you are not getting fuel into the cylinders.
Ok, Thanks. I'm gonna do that and Let Ya'll know the Outcome.
Oh and Mike, I did Try Holding down the Throttle in My Bonneville and Sure enough the engine didn't start! It was like Magic to Me. Wish I knew this before doing all those dumb things.
Is this Only for GM cars/Our Cars Or You can do it on just about any car?

Quote:
Originally Posted by WilliamE View Post
When I did my compression test I just disconnected the ICM, but I was removing all of that anyway to do the UIM/LIM job..
Clear Flood mode is quicker for just compression testing.

Just curious but how were your numbers on the compression?
Did you let the engine run for just a minute or two, enough to get slightly warm, then remove all plugs, then test for compression?
I ask because it is best to do on a engine that is warm, but not hot, you do not want to burn your self from the exhaust manifolds when removing the plugs.

Also a note that you don't learn while watching most videos, let the engine crank until you see the compression tester stop gaining pressure, don;t give it 5 cranks and stop.

With that said try what Mike suggested, and let us know what happens.

Yea I did know about cranking till the Needle stops. And Quite Frankly I didn't go all the way with the Test,. I Started rather early, doing this outside and it was cold as devil, I started with the front bank, after removing the spark plugs; added that I had a hell of a hard time with #1 Spark Plug Boot, spent about 30mins Just trying to remove the Darn thing w/o damaging it [whereas the other took Me less than 3mins to pull]. But anyway, One thing lead to another, I decided to finish up later - - [Long Story]. I Probably I didn't let the engine warm up enough.

Quote:
Originally Posted by WilliamE View Post
Oh yea, the radio went off because it was tied to the ignition fuse, that is so the radio does not stay on once you cut the car off, and remove the key.
I eventually figured it out about the Ignition switch controlling the electronics. I Just can't figure out how unplugging & plugging these things can cause anything not to work like it did.

But Yes, I will do as He said and Yet Ya'll know the outcome.

Thanks A-Thon for coming to My aide with such quickness.

At least I've just learnt something new.
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Old 12-07-2015, 06:34 PM   #7
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With popping fuses out of live circuits you could have blown one. Check all your fuses to make sure they are still good. All the fuses, not just the ones you pulled.
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Old 12-07-2015, 07:58 PM   #8
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Spark plug boots can be a pain to remove sometimes, always be sure to put dielectric grease on the tips of the plugs, it can help a little when you go to remove them.
I recently invested in one of these, I got tired of having wires break, and me having to lay on the engine to try to remove the remaining part of the wire off of the plug.

http://www.amazon.com/Lisle-51250-Sp...9532545&sr=8-1
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Old 12-07-2015, 11:30 PM   #9
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With popping fuses out of live circuits you could have blown one. Check all your fuses to make sure they are still good. All the fuses, not just the ones you pulled.
You know, I was thinking Just that, But wasn't sure. Thank You for confirming My suspicion!, I'll do That 1st Tomorrow and let You Know.
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Old 12-25-2015, 09:15 PM   #10
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Angry Finally Got It Done

I have checked all My Fuses and Relays, all seem to check out. I Pulled all the fuses and checked to see if they're blown, and Tested Relay switches with 12V and Resistance/continuity across the circuits, they all seemed to be working properly.
So what'* My next move/action? Could there have been a wire cut somewhere?

I'm totally lost. I need major help.
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