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Unread 07-08-2013, 01:23 PM   #1
papapegasus
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1978 CJ7 
 
Join Date: Sep 2012
Location: Dallas, NC
Posts: 18
CJ7 Problems...Uhg

Ok, so the Jeep has been back at the shop that put the motor in for a while now. They swapped out the blown AMC 360 with a newly rebuilt AMC 304 bored over 30. All outside parts were still good and were swapped out. Oil pump was rebuilt inside out. I drove the Jeep home with no issues. I only live about 10 miles away from the shop. Went on a trip to town to pickup some goodies for the Jeep, about 8 miles. The problem I ran into was anytime I would stop while the Jeep was in drive, the engine would cut off. It will crank back up everytime until it reached about 190 degrees on the temp gauge, then it won't start again.



They towed it to the shop and have tried the following;



Changing out the ECM for a new one. (The Howell EFI uses an ECM from a 1989-90 model GMC truck with a 350)



Changing the Coil



All electrical systems check out. (Starter, Alternator, Battery)



The engine is getting spark, electric fuel pump is working, the EFI is sending fuel into the engine just fine. Plugs are brand new, gapped to .50 according to ignition system manufacturers instructions. The idle has been adjusted up and down with the same result.



The mechanic is at a loss for what is going on. He said the only thing he can think of at this point is that the engine isn't able to regulate its temp due to boring over, so he is going to try and put a higher temp thermostat in and see if that works.

Any suggestions? I just read about vapor lock, but since the fuel is getting to the EFI and engine strong until it cuts off, this doesn't seem to be the problem.

Luckily I am not getting charged for all of this since they installed the motor!

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Unread 07-08-2013, 01:35 PM   #2
LumpyGrits
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1985 CJ7 
 
Join Date: Jul 2010
Location: The Mojave Desert Palmdale Ca. U.S.A.
Posts: 5,062
What's to install a higher t'stat
Find a new 'wrench' ASAP.
You run'n an auto tranny(details, are a MUST!)?
If so, sounds the torque converter is not 'releasing' the engine at idle speed.
What's your idle set to?
LG
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Unread 07-08-2013, 02:13 PM   #3
papapegasus
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1978 CJ7 
 
Join Date: Sep 2012
Location: Dallas, NC
Posts: 18
Quote:
Originally Posted by LumpyGrits View Post
What's to install a higher t'stat
Find a new 'wrench' ASAP.
You run'n an auto tranny(details, are a MUST!)?
If so, sounds the torque converter is not 'releasing' the engine at idle speed.
What's your idle set to?
LG
Auto tranny, idle sits at bout 900.
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Unread 07-08-2013, 02:20 PM   #4
LumpyGrits
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1985 CJ7 
 
Join Date: Jul 2010
Location: The Mojave Desert Palmdale Ca. U.S.A.
Posts: 5,062
Drop that idle down to 600 in "D".
Who's torque converter are you using?
LG
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Unread 07-08-2013, 02:43 PM   #5
papapegasus
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1978 CJ7 
 
Join Date: Sep 2012
Location: Dallas, NC
Posts: 18
LG,

Will drop the idle down to 600 in drive. I have no idea on the torque converter. It came with the Jeep from the PO. Just spoke with my Father-in-law who had the engine built and is a Jeep guru. He thinks the issue may be fuel vaporizing either in the lines from radiant heat or in the performer intake manifold due to heat.
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Unread 07-08-2013, 05:20 PM   #6
shadoow
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1985 CJ7 
 
Join Date: Nov 2006
Location: Granbury, Texas
Posts: 470
i've seen a similar situation with the engine dying when coming to a stop (auto trans) and it turned out to be a vacuum leak on the intake. Could be a vac hose or connection, carb bolts loose/gasket problem, etc.
Am not sure about the temp situation though
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Unread 07-08-2013, 08:55 PM   #7
KMD
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1976 CJ7 
 
Join Date: Apr 2009
Location: Modesto, California
Posts: 1,284
needs some diagnostics done. Hook a fuel pressure gauge up to it when they drive it. when it dies and will not restart they need to check fuel pressure,spark,and injector pulse. throwing parts at it will do no one any good. simple diagnostics here. they need to pinpoint the system that is failing. Sounds like a distributor pick up coil or module to me. Easy to verify by checking spark when it shuts down.
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amc 304 , cj7 , fuel injection , howell

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