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jtripp
New Member
4 Posts |
 Posted - 11/17/2014 : 08:48:43 AM
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I have a 1993 Chevrolet B7 Chassis with Bluebird body school bus. It has a 6.0L (366) engine with AT545 Allison transmission. I purchased the bus about a month ago.
It idles about 1000 rpm, but once it is put into gear the rpm's drop to about 300 and then bounce up to 1200. It will do this several times before the engine finally dies.
The vacuum checked good with a gauge. When checking the timing, I noticed it has been set way off. When adjusted to the correct position the engine immediately dies. I believe the previous owner or their garage have adjusted the timing to offset some other problem, but I do not know what.
The jets seem to spray good at idle.
Any help is appreciated. |
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baptistbusman1
Senior Member
USA
175 Posts |
Posted - 11/17/2014 : 3:52:27 PM
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| First thing I would do is a total tune up: wires, plugs, cap, rotor and most importantly a new ignition module. The IM will cause all kinds of problems, keep one on hand for this bus! When you re-timed it, did you unplug the brown "shunt" wire inside the bus? It will not time correctly with this wire plugged in. It's located on the inside on the right side to the right of the engine "doghouse". |
I was formally Baptistbusman. However, I lost my password, and had not updated my email address.
Here is a link to my old posts. http://www.schoolbusfleet.com/forum/search.asp?mode=DoIt&MEMBER_ID=1846 |
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Cal Mc
Advanced Member
303 Posts |
Posted - 11/17/2014 : 8:09:52 PM
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| We have replaced a number of harmonic balancers on these engines, The outer ring slips and then the timing cannot be set using a timing light. |
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jtripp
New Member
4 Posts |
Posted - 11/18/2014 : 2:02:22 PM
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quote:
Originally posted by baptistbusman1
First thing I would do is a total tune up: wires, plugs, cap, rotor and most importantly a new ignition module. The IM will cause all kinds of problems, keep one on hand for this bus! When you re-timed it, did you unplug the brown "shunt" wire inside the bus? It will not time correctly with this wire plugged in. It's located on the inside on the right side to the right of the engine "doghouse".
I have replaced the wires, plugs, cap and rotor. Should have put that in my first post. I have not replaced the ignition module. Should I replace the whole distributer?
Also, I did not unplug the "shunt" wire. I will have to look for it.
Does this bus have a check engine light? It is not coming on if so. I would think it would come on with the problems I am having. Would this year bus give a code and would it us a OBD 1 or OBD II connection? |
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baptistbusman1
Senior Member
USA
175 Posts |
Posted - 11/18/2014 : 3:44:34 PM
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I would just replace the module. And if you didn't unplug the shunt, then then there is 0% chance it's timed correctly.
This bus is OBD 1. More than likely it would just give a code saying "Electronic Engine Module" or something like that. The codes have rarely helped me with anything. The OBD 1 port is located to the right side around where the shunt wire is. The shunt should have a black connector on it and it's almost directly to the right of the edge of the doghouse. |
I was formally Baptistbusman. However, I lost my password, and had not updated my email address.
Here is a link to my old posts. http://www.schoolbusfleet.com/forum/search.asp?mode=DoIt&MEMBER_ID=1846 |
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jtripp
New Member
4 Posts |
Posted - 11/18/2014 : 6:34:26 PM
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The top of the distributor was VERY rusted so I replaced it. I found the single brown wire. Once unplugged I was able to set the timing.
It is not stalling out when put into gear. Thanks for your help. |
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jtripp
New Member
4 Posts |
Posted - 11/19/2014 : 12:34:51 PM
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| How do I adjust the idle? I thought there would be an adjustment screw somewhere close to where the throttle cable goes around the cam on the side of the throttle body, but I do no see one. Am I missing a part? |
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baptistbusman1
Senior Member
USA
175 Posts |
Posted - 11/21/2014 : 6:01:33 PM
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| Sorry for the delay. I believe the idle is factory set. It's either controlled by the computer or by the torx screws that are on the throttle body. They say not to mess with the screws as they are factory set. |
I was formally Baptistbusman. However, I lost my password, and had not updated my email address.
Here is a link to my old posts. http://www.schoolbusfleet.com/forum/search.asp?mode=DoIt&MEMBER_ID=1846 |
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1993 6.0L Chevy Engine Stalls in Gear
