Rebuilt engine won't start

[bgreed]

Some read earlier about my buying a 2001 Cherokee with a spun bearing. Well I have rebuilt the engine replacing main and thrust bearings, front and rear main seals, timing chain, can shaft, head, valves and springs, push rods, and a new head (old one was cracked). The problem is now that everything is back together she won't start. Will crank get a little back fire but won't start any ideas?

[XJ Wheeler]

Personally, i would go through all the wiring again to make sure its hooked up right. Then do the usual for a no crank situation. Check fuel, spark, ignition, etc.

Sent via messenger pigeon - i talk, he types.

[4.3LXJ]

Greg, did you reuse the original flywheel/flex plate?

[bluedragon436]

As Jake said, go back through and check all your connections.. make sure your crank position sensor is installed and hooked up... I only say this cause it's hidden and I know it gets missed when reinstalling engines... (mainly cause I did it when I did the engine swap on the 90 XJ I currently have)... and it took a little bit of messing about before noticing it wasn't installed...

[OrangeXJ]

When I put my new engine in it did the same thing. It was the timing. Found out while putting in the distrubuter it was 1 tooth off. It has to be dead nutt on or it will not start. It took 4-5 stabs to get it right then started right up.

[XJ Wheeler]

When I put my new engine in it did the same thing. It was the timing. Found out while putting in the distrubuter it was 1 tooth off. It has to be dead nutt on or it will not start. It took 4-5 stabs to get it right then started right up.

That was my first thought, especially since we've had a few cases of this on the site. But the '01 doesn't have one.

[bgreed]

Greg, did you reuse the original flywheel/flex plate?

Yes reused the original flex plate

[slvmart]

Probably a good idea to go over all the basics related to timing. Timing chain, ignition timing, Firing order (if applicable). If you are 100% sure that is all set correctly, then proceed to the more typical spark and fuel diagnosis.

[bgreed]

When I put my new engine in it did the same thing. It was the timing. Found out while putting in the distrubuter it was 1 tooth off. It has to be dead nutt on or it will not start. It took 4-5 stabs to get it right then started right up.

The 2001doesn't have a traditional distributor it's just a shaft with a gear and a wire no rotor. Will check the crank sensor.

[4.3LXJ]

The next thing i would recommend is to check ignition timing and verify spark at the plugs

[bgreed]

OK an update checked crank sensor it is plunged in on the 2001 you don't have to in plug it to pull the engine. Checked fuel, spark they are OK. Have moved engine to top dead center an restabbed the oil pump drive ( used to be a distributor ) no luck will roll over even back fire one in a while but engine won't catch. It not possible to put the timing chain on when it is not top dead center (marks won't line up) so I'm stumped.

[4.3LXJ]

At this point, I would verify the cam is installed correctly. Do the cam timing marks line up like they are supposed to? Does the piston when going to top dead center push air when you turn it by hand when it goes to TDC? I think you cam timing might be off. Such as maybe 180° out. Getting a back fire once in awhile indicates either cam timing or ignition timing being off that much

[Pookapotamus]

Definitely sounds like a timing issue, does the rotor less dist still control timing to a degree, I mean it still has a gear on it right? Does that not have to be timed to the cam properly?

[bgreed]

Yes the oil pump driver has to be timed. You line up two holes and put a pin in to hold it in place while you install it. I don't know how the can can be out of time you can only put the gear on one way so the timing marks will line up. I fully agree it is a timing issue. oh and yes the pistol pushes air when coming to TDC.

[bgreed]

The timing marks line up. They will only line up if put on one way. The number one piston pushes air at TDC so I'm sure it's on the compression stroke. The oil pump drive has to be alined. There are two holes that put a pin through to hold in place till you install it. I even tried it 180 degrees out of phase still nothing.

[denverd1]

went through this when I did RMS and oil pump. timing has to be exact or it won't fire. the popping tells you fuel and spark are getting there, just at the wrong time. go back through timing. Ironically on my dizzy system, computer still controls spark. got a manual? I've set timing on lots of things, but the later jeep 4.0 system had me scratching my head. Do EXACTLY what manual says, it will fire.