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Unread 07-26-2015, 12:03 PM   #1
PurplePit
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1981 CJ7 
 
Join Date: Feb 2015
Location: Glenwood Springs, CO
Posts: 38
Need help! Starting/pressure issues

Have a TBI and having start issues. When I turn the key on, the system pressurizes for about 2 seconds and then all the pressure bleeds off after that. If I try to start it after that it will just crank and not fire. If I turn the ignition on and try to start it before the pressure bleeds off, it will start right up. Thought it might be an electrical issue and have checked all my terminal wires but everything seems fine. Could it be the pressure regulator in the throttle body bleeding all the fuel out through the return line and giving me dry conditions? Also, when I crank it there is no pressure and no fuel to the injectors when I have the pressure bleed off situation, which still leads me to think electrical...

Any Thoughts?

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Unread 07-26-2015, 01:20 PM   #2
gmakra
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1985 CJ7 
 
Join Date: Jun 2008
Location: Chicago area
Posts: 3,299
Check your pressure regulator for something stuck under the seat.
The pump will turn off after pumping up initially.
You can get a regulator rebuild kit from Car Quest or NAPA for cheap.
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Unread 07-26-2015, 01:45 PM   #3
PurplePit
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1981 CJ7 
 
Join Date: Feb 2015
Location: Glenwood Springs, CO
Posts: 38
Quote:
Originally Posted by gmakra View Post
Check your pressure regulator for something stuck under the seat.
The pump will turn off after pumping up initially.
You can get a regulator rebuild kit from Car Quest or NAPA for cheap.

Would this also cause no pressure while cranking?
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Unread 07-26-2015, 01:46 PM   #4
PurplePit
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Join Date: Feb 2015
Location: Glenwood Springs, CO
Posts: 38
Also, what are the thoughts on possibility of ignition module?
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Unread 07-28-2015, 08:54 PM   #5
PurplePit
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1981 CJ7 
 
Join Date: Feb 2015
Location: Glenwood Springs, CO
Posts: 38
Well, here what has happened since....and the problem goes on and on and on. I start it the first time and it starts up fine (usually) I turn off the ignition and try it again and I have no pressure while cranking and no spray. I have found that I have to turn ignition all the way off and wait a minute before I can try agin and have it work. If I just leave the key in the on position, it will never start no matter how many times I try.

Replaced ECM
Replaced Fuel relay
Rebuilt throttle body
Tested ignition module according to mallory instructions
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Unread 07-28-2015, 09:07 PM   #6
CSP
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Join Date: Aug 2002
Location: Colorado
Posts: 14,012
What have you done to determine that it's actually a fuel problem? Done any fuel pressure testing with the key cranking the starter?


Kinda looks like you're throwing parts at it instead of diagnosing the problem. Have you contacted Howell?
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Unread 07-29-2015, 06:32 AM   #7
PurplePit
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1981 CJ7 
 
Join Date: Feb 2015
Location: Glenwood Springs, CO
Posts: 38
PROBLEM SOLVED!! When I tested the ignition module, I was relying on bad advice from a local mechanic who told me that on voltage drop test (MSI ignition) I would be just fine if it drops to 4-5 volts. Anyhow, spoke to MSI directly yesterday and was told that if the module test does not drop to 1-2 volts upon the module being shorted then the module is bad. If I have 4-5 volts (which I do) then the system is giving off very weak spark and likely will have intermittent starting issues with a TBI.
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