LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

94 Z28 engine will not start up but stutters some and backfires

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Old Oct 21, 2011 | 03:06 PM
  #16  
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Re: 94 Z28 engine will not start up but stutters some and backfires

Originally Posted by capncrunch
... They are a pain in the *** to change in an LT1 Camaro
Try to get ahold of the skinniest, tallest, long armed **** u know so he can use his go-go gadget arms to help you, lol.
Old Oct 21, 2011 | 03:35 PM
  #17  
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Re: 94 Z28 engine will not start up but stutters some and backfires

Changed the plugs...... Still will not start..... Old plugs were wet with fuel..... It must not be getting enough spark from the distributor....
Old Oct 21, 2011 | 03:37 PM
  #18  
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Re: 94 Z28 engine will not start up but stutters some and backfires

yea..... knuckles and fingers are missing skin.... The drivers side is a real bitch!!!!
Old Oct 21, 2011 | 03:47 PM
  #19  
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Re: 94 Z28 engine will not start up but stutters some and backfires

Take the easy way. Put a cylinder at TDC. Then pull the distributor cap off and see if the rotor is pointing in the direction of that cylinders contact (as if the cap was on).

While your there looking for that, you can check the condition of the cap and rotor as well as inadvertently checking a few other things
Old Oct 21, 2011 | 03:56 PM
  #20  
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Re: 94 Z28 engine will not start up but stutters some and backfires

I had a condition like that once and the rotor had come off inside the opti. Had another condition and it was the plug wire coming from the coil to opti had went bad, it was sparking all over the place when I had someone turn the car over while I looked at the engine at night ( I guess it wasn't a strong enogh spark to start). I hope you changed the wires when you did the plugs. Good luck.
Old Oct 21, 2011 | 05:02 PM
  #21  
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Re: 94 Z28 engine will not start up but stutters some and backfires

ok..... so here is the new deal..... I rechecked the spark at the coil... very good.. and loud. Then I rechecked the spark at the plug wires on the passenger side. #2 has great spark... #4 ok but not great spark.. #6 & #8 had minimal spark or none some rotations. I'm sure it's a safe bet to say that the drivers side is the same or worse. This leads me to believe that the cap and rotor are not transmitting the spark well. My next step will be to check to optispark with a meter and make sure it is working... but I think a new cap and rotor is needed.
Old Oct 21, 2011 | 09:33 PM
  #22  
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Re: 94 Z28 engine will not start up but stutters some and backfires

Okay, I'll eat those words- partly, anyway (gas-soaked plugs...) Sorry it didn't fix it!

I just did an Opti change in my convertible a few months back. If you can get it on a lift, or hogh enough off the ground, it's not too hard. Be careful, though. I found out the hard way that the '94 f-bodys have a pin that connects the cam-drive to the distributor, and contrary to popular belief, the pin CAN be put in 'out of time!' (mine had enough wear on it that the weld had worn down in the line-up notch, and I got it in the motor 1 or 2 teeth off)
That will cause some serious backfiring and sputtering!

Advice...
Drain the radiator, THEN jack it back up to work on it (it may help keep the coolant from dribbling all over you while you work on it!)
You only need to remove the fan on the passenger-side of the radiator.
Try to get an MSD cap/rotor with the vent feature. You'll never regret it! (Trust me, I've had two '94s for years, now)
Oreilly's will 'rent' you a puller for the damper.
And 'YES' I would do the wires, if you didn't earlier. They might be the problem, too.
Old Oct 21, 2011 | 11:13 PM
  #23  
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Re: 94 Z28 engine will not start up but stutters some and backfires

It's a splined shaft, not a "pin".

Courtesy of Shoebox:

http://shbox.com/1/93-94_opti.jpg
Old Oct 22, 2011 | 07:57 AM
  #24  
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Re: 94 Z28 engine will not start up but stutters some and backfires

I think the optispark pickups are still working but just the cap and rotor are bad, and I will most definitely replace the wires. I seen the msd unit for sale with the vent yesterday. I will get one soon.
Old Oct 22, 2011 | 09:24 AM
  #25  
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Re: 94 Z28 engine will not start up but stutters some and backfires

Do you know why it was running poorly when parked? Had they just changed the Opti? I think that is what capncrunch is suggesting may have happened - they changed the Opti an got the splined shaft aligned incorrectly.
Old Oct 22, 2011 | 09:40 AM
  #26  
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Re: 94 Z28 engine will not start up but stutters some and backfires

It ran absolutely perfect when it was parked, a friend had stored it at my house for 18 month while he had to go away. I started it every week for that time. When he came back he took the keys and locked the car saying he would pick it up soon.....and never did. It sat for 3 years and he fell on hard times and I offered him $500 for the car and he took it. So now I'm trying to bring it back to life.
Old Oct 22, 2011 | 10:04 AM
  #27  
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Re: 94 Z28 engine will not start up but stutters some and backfires

Yeah Injuneer, Thanks!
If it WAS running well when they parked it, then it may have still drawn moisture (thru the three 'weep' holes in the bottom of the cap- LOL!) into the unit and rusted the opti! Mine had never sat, and it had rust on the pickup ring, and (when I tore it down later) a TON of rust in the back of it.
Unfortunately, these are made with special screws and once the tiny screws rust, there is no way to get inside of them without destroying 'em.
Also, if you are holding it in your hand, take a moment and spin the splined shaft to see how the bearings are feeling/sounding!

So, if it IS 'in time' then you will likely need a new Opti, but feel free to try a cap/rotor first. I just wouldn't bolt anything more together than I had to, before I test-started it. Otherwise you will have to do it ALL again, IF the Opti is bad!

Gotta love the Optis!
Old Oct 22, 2011 | 06:05 PM
  #28  
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Re: 94 Z28 engine will not start up but stutters some and backfires

I think I'm just gonna put a new opti and waterpump since they are off.... The water pump doesn't turn to easy. I'm sure the bearing will die soon..... I know it ran well before because I drove it here... It didn't miss, hesitate, or anything like that. I think putting on new parts will be the best way to go.
Old Oct 28, 2011 | 03:24 PM
  #29  
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Re: 94 Z28 engine will not start up but stutters some and backfires

Ok.... A little update here..... I removed the optispark and was fooling around with it and I noticed my hand was wet.... The opti had water in it and it was leaking out of the three weep holes on the bottom..... So I will be buying a new unit with new plug wires... Probably gonna buy a new waterpump while I'm there.... Any recommendations on what type of opti to buy.... Autozone, MSD , GM...... Thanks.
Old Oct 28, 2011 | 09:19 PM
  #30  
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Re: 94 Z28 engine will not start up but stutters some and backfires

GM or MSD. The GM will be the best 'stock' opti, while the MSD has improvements that will prevent the problem from happening again!
(MSD has a vented opti that doesn't have the three weep holes in the bottom, and actually has the same style of vacuum-tube venting that the '95 and up optis have, to remove any moisture BEFORE it destroys the unit!)
Up to you, both are good!



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