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Unread 06-14-2014, 11:24 AM   #1
brandon789
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1991 wrangler won't start

I have a 1991 wrangler with the factory 4.0. Recently I changed the rear main seal, oil pan gasket and distributor gasket. After I finished I have been unable to get the jeep to start. I can smell fuel on the plugs and hear the pump prime so I assume it is getting fuel. Additionally I pulled a plug to see if I was getting spark and it is. So fuel and spark but still no start.

I tested compression on the cold motor and starting with cylinder 1 got 90,90,80,85,105,80. Other than the 105 they don't seem too far apart. I checked distributor timing twice by finding tdc compression for cylinder one and it seems to be pretty much on. I also changed out the distributor to my old one but still no start. When I try to start it the battery meter is showing around 8 volts and the tach doesn't even hit 500 rpm so I tried to bump start it on the hill near our house but that also failed.

Any suggestions? I've been at this since last night and am at a total loss of ideas now.

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Unread 06-14-2014, 12:47 PM   #2
brandon789
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Checked the codes and got 54, not sure why I would have a problem with both distributors.
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Unread 06-15-2014, 08:40 AM   #3
laybackman
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My guess is the distributor is in wrong. pull #1 plug. Stick finger in that plug hole have a buddy use a large socket and breaker bar on the harmonic balancer bolt to spin the engine slowly clockwise until you feel the compression pushing against your finger. Now, with something long and thin like a piece of 12 awg wire or a straightened out pieced of coat hanger and bring #1 piston SLOWLY up to TDC.

You should be at TDC on the compression stroke. Mark the #1 position on the distributor tower AND the base of the dist. under the cap. Pull the cap. Where is the rotor pointing? It should be just before that mark you made. IF it isn't you got the dist. in wrong. KEEP<IN MIOND that if you have to rotate the rotor shaft to realign the rotor you also have to move the oil pump drive shaft since it is slotted and is driven by the dist.
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Unread 06-15-2014, 10:20 AM   #4
brandon789
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That is what I did to set it. I then checked it a couple times. It is definitely timed right. Im hoping it is that sensor. I have a new distributor coming in on the 17th as a warranty replacement.
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Unread 06-15-2014, 10:56 AM   #5
laybackman
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1991 was an odd year for the YJ 4.0. Example the Vehicle Speed Sensor was used BUT the speedometer was still cable driven so the VSS is a 2 wire sensor not the 3 wire sensor like the 1992 ---> sensors are.

Unplug the plug from the VSS on the T-case. See if that allows it to start up. That VSS sensor could be junk.
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Unread 06-15-2014, 11:02 AM   #6
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Pull the starter relay. It has these pin #s on it. Now associate those #s with the socket that the relay came out of in the PDC.
Pin *86 power from the ignition switch to close the relay and let power from the battery pin #30 flow to pin 87 and on to the starter turning it over until you let the key go.
Pin #85 is ground for the starter relay to operate. That ground comes from the NSS switch if it is an automatic or a ground near the dip stick. If yours is a stick shift make sure that ground is there along with the braided cable ground from the firewall.
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Getting older, I have developed some special skills. I have the ability to cough, sneeze, fart and pee at the same time.

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Unread 06-15-2014, 04:47 PM   #7
brandon789
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Vad didn't change anything. I'm not following your last post, the whole thing went over my head
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Unread 06-15-2014, 08:05 PM   #8
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Quote:
Originally Posted by brandon789 View Post
Vad didn't change anything. I'm not following your last post, the whole thing went over my head
There is a black rectangular box in front of the battery. It is your Power Distribution Center (PDC). Remove the cover. On the inside of the cover it tells you what is what. Find the starter relay. Remove it. Now look at the picture of the relay I posted. Those are the pin #s I used to ID which pin does what. Now does this make sense?

Pull the starter relay. Make sure you are in PARK or Neutral.

Turn the ignition key to the ON position. Now take a length of insulated wire with the ends stripped and jumps pins 30 to 87. Does the starter turn the engine over now?

IF you turn the ignition to the START (not the ON position) pin 86 should show 12 volts on your multi meter. You will need someone to turn the ignition key while you test for voltage. Pin #85 should show ground on your multi-meter. IF either one is missing the relay won't close sending power to the starter
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Unread 06-18-2014, 11:05 PM   #9
brandon789
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Starter relay is fine. It seems like a timing issue now that I got a new distributor. No longer have code 54. I can get it to start and run rough if I turn the rotor clockwise past where I think it should be (more advanced?). Right now I have the distributor in how I feel its supposed to be and the motor seems to start and make a revolution or two on its own then die. One spline clockwise and it runs rough and every now and then a stats to die. It also has a deeper louder sound than before. The pic is how it is set up now and i feel it should be but I can't get it to start.
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Unread 06-18-2014, 11:27 PM   #10
brandon789
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Here is the pic of where it currently is and where I feel it is supposed to be set yet it will not start. The black mark is the far counterclockwise edge of the point for cylinder 1.
Also at 1 spline advanced, where I can get it to idle, when it will run the engine won't go above 2.5k rpm. If i try to rev it higher it will sputter and drop back down to 2.5k.
20140619_004418.jpeg  

Last edited by brandon789; 06-19-2014 at 12:09 AM..
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Unread 06-19-2014, 05:27 AM   #11
laybackman
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Quote:
Originally Posted by brandon789 View Post
Here is the pic of where it currently is and where I feel it is supposed to be set yet it will not start. The black mark is the far counterclockwise edge of the point for cylinder 1.
Also at 1 spline advanced, where I can get it to idle, when it will run the engine won't go above 2.5k rpm. If i try to rev it higher it will sputter and drop back down to 2.5k.
What brand name and model of distributor is that? If could very well be wrong but something doesn't look aligned properly. The pulse ring should be at or near the pick up when you are at TDC on #1 plug or just ahead of the rotor tip.
And I think that the #1 plug position on the distributor cap faces outward towards the fender at about the 9 o'clock position also. Maybe you have the plugs wire on in the wrong position also.

Spec out the pictures of the pulse ring rotor position this link;

http://www.lunghd.com/Tech_Articles/...lse_Stator.htm
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Chicks dig me.....Fish fear me

Getting older, I have developed some special skills. I have the ability to cough, sneeze, fart and pee at the same time.

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David C. Wilker Jr. USAF (RET)
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Unread 06-19-2014, 08:05 AM   #12
brandon789
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It is a duralast gold distributor. I had a duralast one in there before and it worked. I still have the stock distributor with a bad cam sensor that I can look at.
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Unread 06-19-2014, 09:00 AM   #13
brandon789
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The pickup part was in differently so I took it apart and now it is in the same. The part on the rotor is the same astock. I just tried it again and got a backfire through the exhaust that sounded like a gunshot going off.
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Unread 06-19-2014, 11:46 AM   #14
laybackman
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Note the position of #1 plug tower (9 o'clock position) facing AWAY from the engine and also recheck your firing order set up on a stock distributor for a 95 YJ. That is pretty much the same for every years YJ 4.0 engine. Look at your position.
KEEP IN MIND the position of the oil pump drive shaft. It must be placed in the 11 o'clock position.

I am fully aware that one can get the firing order right in six different positions of the distributor by 'clocking' it six different ways. Why do that?

__________________
Chicks dig me.....Fish fear me

Getting older, I have developed some special skills. I have the ability to cough, sneeze, fart and pee at the same time.

"If we cannot afford to take care of Veterans, then we should stop making them."
David C. Wilker Jr. USAF (RET)
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Unread 06-19-2014, 11:55 AM   #15
laybackman
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Could you post a picture of the underside of the rotor that slide over the distributor shaft and a picture of the shaft it sits on? I swear something is out of whack.
Did you get installation instructions with this distributor? Can you post them or the file online if available?


The body of the distributor can only go in one way BUT the rotor/drive shaft can be installed a bunch of ways if the oil pump shaft will accommodate it by moving it to do so.
__________________
Chicks dig me.....Fish fear me

Getting older, I have developed some special skills. I have the ability to cough, sneeze, fart and pee at the same time.

"If we cannot afford to take care of Veterans, then we should stop making them."
David C. Wilker Jr. USAF (RET)
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