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Unread 08-13-2009, 02:50 PM   #1
cmschule
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New motor keeps backfiring and wont start

i
m new here and in need of your help..
i just put a brnad new 360 in my 1987 J20. i got it started and moved it in teh driveway and turned it around... turned it off fixed a couple o fthings. then startesd it again... it was moving then it died.. it woudl nt start again for the life of it.. it came close but didnt go all the way... i have had 2 huge backfires so far.. and i'm scared to try and start it again.. ive messed with the timing to try and get it correct but...idk it backfires really loud... anythign you guys can think of? please help.. this truck brnad new everytign and i really want to drive it..
here is a picture of her


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Unread 08-13-2009, 03:12 PM   #2
CSP
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Sounds like you need to start over with the timing. Pull the distributor, get the #1 cylinder at the top of the compression stroke and stab the distributor making sure that the rotor is pointing at the tower for the #1 spark plug.

The backfiring and wanting to start is a prime symptom of the timing being off.
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Unread 08-13-2009, 03:14 PM   #3
cmschule
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being off as in i have to take off the cover and find out where it is suposed to go?
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Unread 08-13-2009, 03:28 PM   #4
ChicagoYJ
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Quote:
Originally Posted by cmschule View Post
being off as in i have to take off the cover and find out where it is suposed to go?
No. Your timing is not set right. Do what CSP said to do on above post. That will help you set it correctly.

Take the distributor off, not the timing cover.
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Unread 08-13-2009, 03:32 PM   #5
cmschule
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before i installe the motor i had the intake off and i made sure that it was at top dead center... then iput the ditributer in with the rotor facing towards teh #1..... the truck ran fine.. but then it died.. i think somethign else might have happened
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Unread 08-13-2009, 04:13 PM   #6
CSP
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You don't take anything off to determine TDC. Pull the spark plug out of the #1 cylinder. Have someone bump the starter over and watch for the timing mark on the harmonic balancer. As it approaches the timing marks on the front of the engine stick your finger over the spark plug hole and feel for air coming out. If air isn't coming out that cylinder is on the exhaust stroke. It must be on the compression stroke.

My guess is you stabbed the distributor the first time with #1 at the top of the compression stroke or you're off a tooth on the distributor. Sometimes they will run (but very roughly) if you do either one.

Troubleshooting is about eliminating variables and this is the easiest variable to eliminate.
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Unread 08-21-2009, 06:12 AM   #7
77wagoneerman
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My problem when it exhisted, when my Waggy wouldn't start and ran like the above, was a points and condensor change. I am sure an 87 is electronic, but worth alook. Nice looking Jeep you have their, I hope you get her on the road.
http://i468.photobucket.com/albums/r...s/DSC05642.jpg
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Unread 08-22-2009, 07:12 PM   #8
90grandoneer
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Before you take the dist. out, make sure the wires in the cap are in the proper sequence and in the same direction as rotation. if all is good there, then check dist. installation as indicated above.
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Unread 08-22-2009, 07:27 PM   #9
77j20
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Make sure all your plug wires are attached. I was sitting at a stop light when my J truck started running real rough and had no power, i pulled over opened the hood and the 2 plug wires on the back passenger side had fallen off (the only 2 my buddy put on).
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Unread 08-27-2009, 10:40 AM   #10
carnuck
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Dist left loose?
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