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Ranger Rick
User
Oct 10, 2011, 9:42 AM
Post #1 of 25
(3814 views)
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No Start on Jeep 4.0
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We have "freshened" a 4.0 Jeep motor, new bearings lapped the valves new cam and timing chain. We got everything buttoned up, and tried to light it off, nothing, not even a backfire through the throttle body. We did bleed the fuel rail and we checked for spark, both look great. The plugs finally even got wet so we are pretty sure that the injectors are working. We pulled the #1 spark plug and checked timing by putting finger in hole and when the air came we looked at the distributor, and it was pointing at # 1 on the cap Compression is over 130 on all cylinders. We have replaced the crank sensor in the thought we bumped it when installing the engine back into the Jeep. We are beginning to wonder about the cam timing, when we installed the cam, we counted the 15 pins and everything looked great, proven by the fact that the distributor timing is correct for the spark and the compression is good. WE have worked around engines for years, and this one has stumped us. We have gone back and checked all connections and all grounds, but can not find any reason for it to not start. Any Ideas?
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Hammer Time
Ultimate Carjunky
/ Moderator
Oct 10, 2011, 1:48 PM
Post #2 of 25
(3790 views)
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Re: No Start on Jeep 4.0
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All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.
Every engine requires spark, fuel and compression to run. That's what we have to look for.
These are the basics that need to be tested and will give us the info required to isolate a cause.
1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.
2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.
3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.
4) If all of these things check good, then you would need to do a complete compression test.
Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Ranger Rick
User
Oct 10, 2011, 3:57 PM
Post #3 of 25
(3785 views)
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Re: No Start on Jeep 4.0
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1. We have spark, we had a plug out and grounded to the engine and it actually flashed the fumes coming out of the cylinder! The plug was 6 inches away from the hole!
2. This kind of goes with 1, the injectors must be working to provide enough fuel to ignite out of the motor.
3. we have 36 psi when the engine is not cranking and 38 when it is.
4 compression will go to at least 100psi on the first stroke and climb to 140 on the remaning crank strokes. This is an average for all 6 cylinders, with the low being 95-135 and the high being 110-145. We know it is not a new engine, but it should run with that. I have seen worse and still run
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Hammer Time
Ultimate Carjunky
/ Moderator
Oct 10, 2011, 4:02 PM
Post #4 of 25
(3781 views)
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Re: No Start on Jeep 4.0
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There has to be serious flaws and omissions with your testing. With those results, the engine would be running. Please finish the testing more accurately including injector pulse and fuel pressure.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Discretesignals
Ultimate Carjunky
/ Moderator
Oct 10, 2011, 4:16 PM
Post #5 of 25
(3775 views)
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Re: No Start on Jeep 4.0
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Make, model, year?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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Ranger Rick
User
Oct 10, 2011, 4:40 PM
Post #6 of 25
(3768 views)
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Re: No Start on Jeep 4.0
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The engine is out of a 95 xj and is a 4.0 we have re installed the intake, exhaust, distributor, from the original 97 TJ. and it is going back into the TJ So everything but the long block is the original parts from the 97 TJ. The bad thing is, the TJ was running when we brought it in! It had a hole in #6 so it did not run too well. The engine from the 95 was in pretty good shape with the exception of the rod bearings looking a little rough on the tops. The crank Plasti-guaged just fine so we rolled a new set of bearings and a new RV cam into it with a new timing chain. As far as we were to be able to determine there was nothing different between the 95 and the 97. Everything hooked up just fine.
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Discretesignals
Ultimate Carjunky
/ Moderator
Oct 10, 2011, 5:45 PM
Post #7 of 25
(3763 views)
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Re: No Start on Jeep 4.0
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Are you using the 95 flywheel/flexplate? Crank sensor uses the flywheel/flex plate as the interrupter. Jeep did some weird redesigns with flexplates/flywheels. I looked up the part numbers for the 97 and the 95 flywheel and they have different numbers, so you might want to check that out if your using the 95 wheel/plate.
If the window/interupters are different, it's going to throw off your ignition and injector timing.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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Ranger Rick
User
Oct 11, 2011, 8:37 AM
Post #8 of 25
(3747 views)
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Re: No Start on Jeep 4.0
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Nope we are using the 97 out of the same Jeep it came from. The 95 was a manual so it would be hard to put into a rig with an auto! Nice thought though! We are going to change plugs tonight just to see if the ones in it are just too fouled to fire, I really have a hard time believing that but you never know!
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Ranger Rick
User
Oct 15, 2011, 2:55 PM
Post #9 of 25
(3724 views)
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Re: No Start on Jeep 4.0
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I have tested the fuel pressure again and again we get 36psi without engine crank and right at 40 psi when cranking. We are getting 96 rpm on the snap on solas we have plugged in but I notice no injector pulse width time. I got a set of Noids and the injectors are flashing.
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Sidom
Veteran
/ Moderator
Oct 15, 2011, 5:33 PM
Post #10 of 25
(3720 views)
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Re: No Start on Jeep 4.0
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I haven't read this whole thread. I stopped at the "rotor pointing at #1".
If the rotor is pointing at #1 in the cap @ TDC then the distributor is installed incorrectly....
Check the book & follow the procedure word for word......old school doesn't work on this one....
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Ranger Rick
User
Oct 16, 2011, 7:53 PM
Post #11 of 25
(3695 views)
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Re: No Start on Jeep 4.0
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Well we got it running this afternoon. I turns out the pin in the comp cam we bought was inserted in the wrong hole. The cam has 2 holes 180 degrees apart. We timed the cam 180degrees out of time and the motor stared and ran quite well. We will be having a conversation with Comp Cams tomorrow!
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Mr.scotty
Enthusiast
Oct 16, 2011, 8:30 PM
Post #12 of 25
(3694 views)
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Re: No Start on Jeep 4.0
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So.., is this like a rock crawler or off roader?
I wouldn't mind seeing a pic or two.
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Your only as good as your tools!
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Ranger Rick
User
Oct 16, 2011, 8:34 PM
Post #13 of 25
(3691 views)
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Re: No Start on Jeep 4.0
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Naw it is just a 97 TJ. A kid I know owns it, it has had the front fenders hacked off and a 3" lift with 32 inch MUD TA on it , really nothing special, he uses it to go fishing around here.
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Mr.scotty
Enthusiast
Oct 16, 2011, 8:36 PM
Post #14 of 25
(3690 views)
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Re: No Start on Jeep 4.0
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Oh..
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Your only as good as your tools!
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Hammer Time
Ultimate Carjunky
/ Moderator
Oct 17, 2011, 3:26 AM
Post #15 of 25
(3683 views)
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Re: No Start on Jeep 4.0
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There is really no such thing as 180 out on the camshaft. It works in either position. The problem is that the distributor has to be timed to the cam after it's installed. By moving the cam, it was actually the distributor that you were moving. The cam is still in the same place, just one revolution later.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Ranger Rick
User
Oct 17, 2011, 8:22 AM
Post #16 of 25
(3673 views)
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Re: No Start on Jeep 4.0
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When we rotated the cam 180 degrees, we also moved the distributor back to the 5:00 position where it had to be to fire #1. WE had the cam located on the timing marks and the distributor on the 5:00 mark and the engine would not start. When we moved the cam 180 degrees and the distrubtor back to 5:00 then the engine started. To me it sounds like the locating pin in the cam was in the wrong hole. the crank makes no difference as long as it is at TDC when the cam is timed to it. Am I wrong on my thinking?
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Hammer Time
Ultimate Carjunky
/ Moderator
Oct 17, 2011, 8:37 AM
Post #17 of 25
(3670 views)
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Re: No Start on Jeep 4.0
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When the cam is 180 out, if you simply rotate the engine one revolution, it will no longer be 180 out.
The crank turns twice to one revolution of the cam.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Oct 17, 2011, 8:38 AM)
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Ranger Rick
User
Oct 17, 2011, 8:39 AM
Post #18 of 25
(3664 views)
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Re: No Start on Jeep 4.0
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But then the distributor will be 180 out and the exhaust valve will be open
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Sidom
Veteran
/ Moderator
Oct 17, 2011, 9:51 AM
Post #19 of 25
(3661 views)
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Re: No Start on Jeep 4.0
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Only if you didn't pull the #1 plug & bring it up on the compression stroke, then there could be a chance of the dist being 180° out.
But hey........glad to hear ya got her going.....Those can be a PITA sometimes......I have the lack of hair to prove it...
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Ranger Rick
User
Oct 17, 2011, 10:41 AM
Post #20 of 25
(3655 views)
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Re: No Start on Jeep 4.0
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I hear you! I dont know how many motors I have built, but this one was by far the most stubborn!
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Hammer Time
Ultimate Carjunky
/ Moderator
Oct 17, 2011, 11:15 AM
Post #21 of 25
(3650 views)
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Re: No Start on Jeep 4.0
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The distributor can be 180 out but the cam cannot.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Ranger Rick
User
Oct 17, 2011, 12:24 PM
Post #22 of 25
(3644 views)
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Re: No Start on Jeep 4.0
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yep i see your point!
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FUN MUDDER
New User
Jan 25, 2012, 10:30 PM
Post #23 of 25
(3486 views)
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NO START
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WHERE SHOULD MY ROTOR BUTTON FACE AT ON THE CAP PRONGES WHEN I HAVE MY 4.0 IN TIME ? I JUST REBUILT THIS MOTOR AND PUT IT IN AND IT DOESNT SEEM TO WANNA START IVE PUT THE CAM AND CRANK IN THE RIGHT TIME I THINK??? THE VALVES ARE SHUT ON #1 AND THE PISTON IS UP ON THE COMPRESSION STROKE I DROPPED THE DISTRIBUTOR IN AND THE ROTOR BUTTON FACED #1 ON THE CAP BUT IT STILL WONT START IVE CHECKED EVERYTHING YOU GUYS HAVE BEEN TALKIN ABOUT ON THIS POST. BUT I DONT HAVE A MANUAL SOO IM JUST LOST ON THIS I AM GETTING PLENTY OF FUEL AND DARN GOOD FIRE IT HURTS QUITE ALOT ACTUALLY WHEN IT BITES YOU BUT .IT JUST ACTS LIKE IT IS TURNING OVER SLOW.IVE TRIED PUTTIN THE DISTRIBUTOR IN 180% BUT IT STARTED TO BACKFIRE THROUGH THE INTAKE. IS THERE ANY HELP YOU CAN GIVE ME
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FUN MUDDER
New User
Jan 25, 2012, 11:07 PM
Post #24 of 25
(3484 views)
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Re: NO START
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IM NOT SURE WHAT I DID BUT I WENT BACK OUT AND STARTED FROM SCRATCH . I GOT IT ALL BACK IN TIME AND IT DID THE SAME THING JUST TURNING OVER FOR SOME REASON I DECIDED TO TAPE THE THROTTLE AND IT FIRED RIGHT UP AND NOW IT IS DOING FINE.IF YOU HAVE ANY IDEAS ON THAT IM GLAD TO HEAR BECAUSE I AM ALWAYS EXCITED TO LEARN SOMETHING NEW AND YEA IF I SOUND A LIL DUMB SORRY BUT THIS IS MY FIRST ENGINE IVE EVER TORN DOWN INTO THE BLOCK THANKS FOR ANY INFO AND YOUR TIME I WILL DEF. BE VISITING THIS SITE MORE I LEARNED ALOT FROM YOUR POSTS TODAY THANKS
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Hammer Time
Ultimate Carjunky
/ Moderator
Jan 26, 2012, 3:59 AM
Post #25 of 25
(3480 views)
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Re: NO START
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This is an old question that belongs to someone else. If you need help with something , then you need to start a new question of your own.
PS, drop the "ALL CAPS" when you do.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Jan 26, 2012, 4:00 AM)
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