Jeep Wrangler Forum

Jeep Wrangler Forum (http://www.wranglerforum.com/)
-   YJ Tech Forum (http://www.wranglerforum.com/f218/)
-   -   91 YJ still wont start (http://www.wranglerforum.com/f218/91-yj-still-wont-start-238354.html)

bubbadah 04-28-2013 05:02 PM

91 YJ still wont start
 
Ok I replaced the CKS and no improvement. Intermittent starting followed by bad running and stalling. I do have spark at the plugs and the coil. I poured fuel in the manifold and tries it and it seems the same. I also ran a screwdriver across the large bolts on the starter and the starter turned. I am missing something. This is on a Dix cylinder with auto transmission.

Squirrel 442 04-28-2013 06:04 PM

you replaced the throttle position sensor (tps) right? My motor would start sometimes ... run for a few seconds .. run rough then die and would not start.

That was after i replaced the cks. When the cks went out it would not start at all.

If I remember right you said you put on a new tps right?

bubbadah 04-28-2013 07:36 PM

Not yet but the CPS is thirty bucks so I may as well go for it.

bubbadah 04-28-2013 08:32 PM

Ok I just picked a TPS up. As soon as the Tri Tip gets done cooking I will install that.

Squirrel 442 04-28-2013 09:31 PM

yeah those symptoms fit what mine did to the T. These jeeps sure do have a lot of sensors! Hope it works for ya

bubbadah 04-28-2013 09:52 PM

Ok now I am sad, did the tps and no go. Not sure where to go. I have spark. I hear the fuel pump prime. I have done the crankshaft sensor.

Squirrel 442 04-28-2013 10:05 PM

confirm you have fuel, you know you have spark ... it would seem to be timing if you have both and she won't fire. Does the motor backfire or sputter? I actually smelled fuel.

Did you run a fuel system cleaner through? Those almost always plug fuel filters unless it is done on a regular basis.

Squirrel 442 04-28-2013 10:13 PM

Do you think resetting the computer will help? I was told to do a factory reset after every sensor change. pull the pos + and neg - cables and touch them together for 15 seconds.

Also give a brief history of what you have done so far, maybe some one will think of something we missed.

Squirrel 442 04-28-2013 10:17 PM

Also,

You do have a strong spark at the plug correct? A little weak flicker will not do the trick.

tbloid 04-28-2013 10:22 PM

This sounds very familiar to what I have going on. I have another thread going to try and find help. Mine is a 91 yj with the 2.5. You have gone farther than I have with replacing sensors. That will probably be my next step after the fuel pressure regulator.

bubbadah 04-29-2013 11:31 AM

I guess good spark vs a bad spark Is the question. I pulled the boot off plug and put it next to the plug and could see nothing's. I inserted an insulated screwdriver in the spark plug boot and held the screwdriver next to the block and got spark. I can't say for sure I am getting excellent spark and it may be intermittent. There are times when the engine wants to fire and then times when it's completely dead. I could have spark at that time. When a coil fails, does it fail 100 percent? Or cod it cause an intermittent deal like this?

Squirrel 442 04-29-2013 02:47 PM

bad coil could cause what you are describing. Is it the original? Watch a couple of youtube videos to see if you can compare good spark to weak spark.

Make sure you have a good ground to the spot you are trying to get a spark or it will be weak.

bubbadah 05-03-2013 10:35 PM

Ok tried the coil and I am still stuck. It cranks and nothing. Occasionally it tries to crank and once in a while it starts and runs. At one point I got it to idle for ten minutes and then it died. I am at $120.00 in parts and I am nowhere. I think I may be towing it to mechanic.

tbloid 05-03-2013 11:21 PM

Mine had the same issue, I finally got it going. The thread is named 91 yj won't start...help!!! Or something close. Turned out to be a faulty fuel pressure regulator. Mine started working again after some work on it, but the diaphragm was good.

First thing to check would be the vacuum line to the regulator. If it's dry then the diaphragm is ok.

Next would be to carefully pull the return fuel line from the fuel rail. Have a piece of hose to slide onto the nipple (to route the fuel away from the engine compartment and into a gas can). The return line is the one closest to the radiator. With the hose in place turn the key on so the fuel pump runs. See if fuel is going through the hose you put on. If there is the regulator could be stuck like mine was. Make sure you have no leaks and try to start it this way. If no go, use a vice grip and pinch the hose tight and try to start it. (When I did this it forced the diaphragm to move and also flooded the engine. Now pull the fuel pump relay ( it's located in the engine. compartment in front of the battery. Second one from the engine side of the box. Now the fuel pump won't run. To clear the flood situation you can try to start it while holding the accelerator to the floor. Keep turning it over until it starts to run. It will die when the fuel is burned out. If you are severely flooded like I was, you may need to have someone help by turning the motor over with the gas pedal held down. And when it begins to run be at the ready to put the relay in to start the fuel pump. It will run rough for about a minute or so, may need to pump the gas slightly to help it run. But it should come out of it.

I hope this helps.

tbloid 05-03-2013 11:23 PM

I forgot to mention to replace the return fuel line before you try to clear the flooded situation. And check for any leaks also.

Squirrel 442 05-04-2013 12:05 AM

Quote:

Originally Posted by bubbadah (Post 3717052)
Occasionally it tries to crank and once in a while it starts and runs. At one point I got it to idle for ten minutes and then it died.

When mine did this ^ it was the TPS throtle position sensor, can't remember if you replaced that yet.

bubbadah 05-05-2013 09:21 PM

Yes I did the tps, I am stuck again. I hate to keep throwing money at it. I am thinking cap, rotor. Wires and plugs. I am planning that anyway but it was running fine and the plugs, cap and rotor look ok. I will spend the week tracing all the wiring but I might end up towing it to a mechanic.

bc3_Jeep 05-05-2013 10:20 PM

Just a note on SPARK...... you should be able to HEAR a good spark.......and it should be BLUE-WHITE...... not yellowish.....

bubbadah 05-06-2013 05:15 PM

I have spark but am having difficulty telling good from bad. If it I a weak spark, and I did the coil it would mean wires cap and rotor. I will try and check again and see what I get. Maybe it's that simple.

Garyk 05-06-2013 06:53 PM

Grab ahold of the plug wire, if it knocks you on your ass, its a good spark. If it just gives a little jolt, its weak...:)

Squirrel 442 05-07-2013 10:10 AM

Quote:

Originally Posted by Garyk (Post 3726309)
Grab ahold of the plug wire, if it knocks you on your ass, its a good spark. If it just gives a little jolt, its weak...:)

Funny cause it's true :rofl:

bubbadah 05-07-2013 08:24 PM

I have a weak ticker, probably going to pass on that method.

Garyk 05-08-2013 04:16 PM

You mentioned that it had been running fine. What happened? Did you change something or do some work? Can't remember what was done.

Squirrel 442 05-08-2013 04:29 PM

Google strong spark or weak spark and watch some videos on youtube

bubbadah 05-13-2013 08:38 PM

I had a buddy come over and we are thinking fuel pump. We can't here it priming. When I press the pressure release on the fuel rail I get vey little fuel . I was going to go borrow a pressure gauge but wonder If I'd be wasting my time. If no fuel shoots out of that valve and we can't hear the pump it seems a slam dunk. Any thoughts?

CMike357 05-15-2013 10:17 AM

Not to be a smart A$$ but is there fuel in the tank. Remember the movie Sling Blade.
It happens!!!!!!!

bubbadah 05-16-2013 07:52 PM

That would be really funny but yes, a full tank of gas. That will make dropping the tank fun if I need to go that route. I hear absolutely nothing from the pump so hopes are high. As soon as I get a bit of time my plan is to inspect all wiring leading from that fuel pump and then check the pressure at the rail. I will also disconnect the fuel line and see how much pressure is in the line just to be sure it's not the fuel pressure deal on the fuel rail.

bubbadah 05-27-2013 06:00 PM

Ok now I am perplexed. Zero pressure at the rail so I did the fuel pump. Same symptoms plus my fuel gauge is pegged on full. I must have messed up putting it back in the tank. Will need to drop the tank again. Starting to feel I am throwing good money after bad at this point.

bubbadah 05-28-2013 02:01 AM

Turned out it was ground wire to fuel pump. It's at the parking brake and I am the idiot who accidentally disconnected it. A number it cost me a dew bucks but the way I look at it, most of the items I replaced would have needed it sooner or later

Babasnoopy 05-28-2013 08:14 AM

Quote:

Originally Posted by bubbadah (Post 3799133)
Turned out it was ground wire to fuel pump. It's at the parking brake and I am the idiot who accidentally disconnected it. A number it cost me a dew bucks but the way I look at it, most of the items I replaced would have needed it sooner or later

Same thing happened to me when I replaced my Parking Brake assembly. It took me two weeks of trial and lots of error. I realized it when I slammed the door one night and the engine stalled. Easiest fix I've ever had though. She runs like a top now!


All times are GMT -5. The time now is 03:20 AM.