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Rebuilt engine won't start...Please help!

Y

YosemiteJeeper

NAXJA Forum User
Location
California
Rebuilt engine won't stop...Please help!

1991 XJ Laredo auto 4.0L Six cylinder : I rebuilt the engine completely making sure to take my time and do it right. Now its in and it won't start. Here's what happens...

I turn the key and it turns over fine. Shows oil pressure. It sounds like its starting to fire up but only for a second then it goes back to just turning over. Before I replaced the CPS it didn't even try though. It does this a few times--sometimes more sometimes not at all--during a ~10 second attempt. I smell fuel from the exhaust, so my thoughts are its getting through at least some of the injectors. I pulled my brand new Bosch platinum +2 plugs and 3-4 of them were coated in what appeared to be gas (smelt like it) So I don't know if they're firing.

I checked the plug wires, checked all the connections I could find, hit 'em them with cleaner and dielectric grease. Checked my grounds they looked fine and I refreshed some of them. Cleaned inside the distributor cap. I was very careful in setting the timing. As I said everythings brand new so I shouldn't have low compression because of piston-cylinder clearance, head gasket, ect. Head was rebuilt. I don't have the equipment to test compression, fuel pressure or spark. And nobody's willing to hold the wire/plug while I turn the key to test (can't say I blame them...) I might be able to get it if other things don't work.
Can somebody help me here? I've spent so much in both time and money on this, its killing me to have her sitting there not running yet. Thanks in advance
 
Re: Rebuilt engine won't stop...Please help!

I would deffiinately check the distributer to make sure its timed corectly and that you have the plug wires on the correct posts on the cap and the coil on the middle one.
 
Re: Rebuilt engine won't stop...Please help!

You don't have to hold the wire while testing... they sell a small spark test tool that plugs into your spark plug wire and has an adjustable gap that the spark has to jump across...the tool has an alligator clip that you use to clip it to ground. Sells for a couple of bucks at Autozone. Have your friend turn the key while you check for a spark jumping the gap on the tool.
 
After a rebuild with all that new engine paint, check your coil grnd and that the wires are properly hooked up to the coil. Also make sure your distributor is well grounded. Obviously if you're getting twelve volts in and nothing out, there you are.
 
Yeah get the spark tester, find fuel and spark first. Then you can go from there. After that I would check your compression. Look on the bright side your gonna get to buy some cool new test equipment.
 
This isn't likely the cause of your problem, but the general concensus after numerous owners reporting misfires is that the Bosch plug isn't a good choice for the 4.0

For a 1991, the simple Champion Coppers are just fine and never have an issue.

For a no-start, verifying a strong, blue, snapping spark AT the plugs is job #1. Find a friend to turn the key while you hold the plug wire so that the electrode is near a good engine. Use an insulated pliers. Or you can just prop the plug electrode near that ground.
 
haha new equipment is good, but lack of money is bad...however a rig that starts is better, so I'll go to my parts place today and see what I can get. I should probly charge the battery too..I think they're all laughing at me, this'll be the 4th time, 2nd in 2 days lol Thanks guys, I'll post what happens.
 
Sounds like the classic situation where your distributor is 180 degrees out.
 
It sounds like when you put it together you got the distributor pointing to the #1 cylinder on the exhaust stroke, not the compression stroke. Remember that the distributor turns half the speed of the crank so there are two points as the distributor rotates where the crank will be at TDC. The simple way to find out is to simply pull the distributor and replace it 180 degrees from where it is pointing now. Also there is a good chance that all the cranking has also wet fouled the plugs and you may need to pull them, clean them, and dry them off.
 
Well, I turned the distributor around. Now it sounds like the starter is trying to overcome the force of the air/fuel charge going off? I'm redoing all my timing today, #1 TDC (on the RIGHT stroke) Dist. to #1. It might have been off to start with, but only a couple teeth. I'll be even more careful this time.
 
With the rotor pointing to the #1 cylinder post on the distributor cap, the timing should be pointing to about 14btdc.
 
Reset the timing and still no start. I checked for spark and it was there. I had someone crank the engine while I held the valve on the fuel rail open and the flow just jumped over the valve cover and hit near the distributor, it didn't spray to the hood. Changed the fuel filter but still no start.
 
When I was piecing mine together I had your problem. Did anyone drop the ignition coil??

My dad dropped mine and I didn't know about it. It was barely a hairline of a crack, but that's all it takes for it to become a dud. Double check yours to make sure there aren't any itty-bitty cracks in it.

Also, make sure you pull out your plugs (all of them) and let the engine turn over a few times to throw all that extra fuel out. I'm sure it's clogged with it right now if you had to turn it as many times as we did to figure out the coil was no good.

Wayne P.~
 
YosemiteJeeper said:
Reset the timing and still no start. I checked for spark and it was there. I had someone crank the engine while I held the valve on the fuel rail open and the flow just jumped over the valve cover and hit near the distributor, it didn't spray to the hood. Changed the fuel filter but still no start.
Click to expand...

Also note that I did have small amounts of spark, but it was weak. So you may see SOME spark, but it might not be enough. Mine almost started the first time. Then from there it just turned and didn't start.
 
The other issue that comes with cranking and no start is that you can wet foul the spark plugs. After a while, they just won't spark enough to get it started. At this point in time I would snag a cheap set of champion plugs and swap them in. Also make sure the battery is fully charged. If it gets low, the computer will not generate a good spark even though the engine is cranking.
 
HttpWayne said:
When I was piecing mine together I had your problem. Did anyone drop the ignition coil??

My dad dropped mine and I didn't know about it. It was barely a hairline of a crack, but that's all it takes for it to become a dud. Double check yours to make sure there aren't any itty-bitty cracks in it.

Also, make sure you pull out your plugs (all of them) and let the engine turn over a few times to throw all that extra fuel out. I'm sure it's clogged with it right now if you had to turn it as many times as we did to figure out the coil was no good.

Wayne P.~
Click to expand...

Also, don't stand on the spark plug side while your bud turns it over to clear out the gas.
 
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