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Hey all, nice to talk to some jeep enthusiasts. so I'm a new member, but not to your forum. and i got a ton of good info from all your input. anyways i have just bought my first Mj (89 4.0 Sport truck (whatever that means)auto, 4wd) and big surprise it has some problems, like the cad, which was a great design. and a starting problem. so my first question is would the shimmed collar in the the cad be good idea in a daily driver. the second is a little more tricky, it has a hard time starting after its been sitting for a couple of hours, now a shot of starting fluid will get it to start perfectly. wile running i know i have 31 psi at the rail, when i unplugged the fuel pressure regulator it jumped to 40 psi. so I'm sure its not a spark issue. i guess what I'm trying to find is if maybe you think I'm loosing pressure while its off(unless its supposed to) i dunno maybe someone has had the same problem as me a could steer me in a good direction. thanks

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Just went thru the same thing you did. I didn't do it ssooner because I refused to believe that it was the problem. It was. Find the connector for the CPS. Unplug it. Plug it back together. The terminals get dirty and that will clean them. Mine runs perfect after I did that, no more problem. Then spray the CPS with brake cleaner. And the flywheel. There are several threads on this. Use search and see what you come up with, or more than likely some of the guys on here will send you a link. Luck, Jim

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Your fuel pressure is with in range of the spec's, in fact, right on :thumbsup:

 

What could be happening, is the injectors are leaking down while it's sitting, a common problem with age, and mileage.

 

You could replace the injectors with new "re-build" ones that might solve the problem, there are a few topics on that subject.

 

Try this trick........turn the key "on" and wait a few seconds......like 30 seconds. Then hit the starter, and see if it starts any quicker. The will re-pressurizer the fuel rail. I need to do that to my MJ.

 

If your into Jeep, then you know that the Renix system is not a super quick start, it take the engine to rotate about 3-4 turns for the CPS to do it's thing and tell the ECU to fire the engine.

 

As far as shimming over the CAD, not all of us have done it, I had to replace the vacuum motor a few years ago, and had no problem afterwords, I like the CAD to work as it should, but I'm sure you'll get different answers on that subject around here.

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now i did t cps unplug trick the other day, nothing. plus wouldn't that be a spark issue, I'm almost positive it is a fuel problem. but i will say i think i have a bad rear main seal, so dirty flywheel. and would i wave white smoke in the morning if my injectors were leaking down. i dunno I'm trying to diagnose the problem before a lot of money is involved, but after all it is a jeep and i know what to expect.

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Your post is very confusing.

 

wile running i know i have 31 psi at the rail, when i unplugged the fuel pressure regulator it jumped to 40 psi. so I'm sure its not a spark issue.

How does measuring the fuel pressure tell you that it isn't a spark issue? The fuel pressure regulator doesn't control the spark.

 

i guess what I'm trying to find is if maybe you think I'm loosing pressure while its off(unless its supposed to) i dunno maybe someone has had the same problem as me a could steer me in a good direction. thanks

What exactly is the starting "problem"? Your 1989 is a Renix system. The Renix system requires several revolutions of cranking before it sarts, and that's normal. If your "problem" is simply that it doesn't start the instant you turn the key ... that's normal. As to losing pressure while parked, in an older vehicle that's quite possible. The solution is to turn the key to the RUN position and leave it there until the fuel pump stops running (indicating full pressure), then turn the key to START.

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Your post is very confusing.

 

wile running i know i have 31 psi at the rail, when i unplugged the fuel pressure regulator it jumped to 40 psi. so I'm sure its not a spark issue.

How does measuring the fuel pressure tell you that it isn't a spark issue? The fuel pressure regulator doesn't control the spark.

 

i guess what I'm trying to find is if maybe you think I'm loosing pressure while its off(unless its supposed to) i dunno maybe someone has had the same problem as me a could steer me in a good direction. thanks

What exactly is the starting "problem"? Your 1989 is a Renix system. The Renix system requires several revolutions of cranking before it starts, and that's normal. If your "problem" is simply that it doesn't start the instant you turn the key ... that's normal. As to losing pressure while parked, in an older vehicle that's quite possible. The solution is to turn the key to the RUN position and leave it there until the fuel pump stops running (indicating full pressure), then turn the key to START.

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