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

[dennis461]

There must be a hundred threads about why a XJ won't start.
Read them all slowly and try all that stuff.

How can you rebuild an engine and not have a compression tester, fuel pump pressure gauge, timing light. Just puzzled, not starting a fight.

Here are some engine rebuilding mistakes;
two head gaskets instead of one ( been there done that) results in low compression, no start.

Timing chain installed wrong, did you have someone besides yourself check the timing marks? Di you rotate engin in the proper direction to remove chain slack before checking marks?

Does the timing chain gears have woodruff key to hold them in place?

Do XJ pistons have a front and back? I think they do, if backwards they could block the valves reducing intake or exhaust flow.

 

[YosemiteJeeper]

Wanye P. : Thanks for the tip, I'll take a look at my coil. It shouldn't be damaged, it just sat on the shelve while I was working on everything else but you never know. I pulled the plugs and pushed the fuel out when I checked the spark.

I found my charger, so I don't have to bug the parts peoples to charge it. Don't wait as long either lol

Dennis : Just lucky that way I guess I did go buy a torque wrench and a feeler gauge though hahaha ok so...Unless Fel-Pro sells head gaskets in pairs, thats not the issue. Timing chain was installed by me (I did all but 10 minutes work myself lol) and exactly as the Haynes manual said to do it. The woodruff keys are in place on the damper and crankshaft gear, the camshaft had a locating dowel. Pistons do have front/back, or at least mine did and yes, they are installed properly. I was exceptionally careful. This being my first rebuild, no help, I did it by the book and took as long as I needed to do it right. My rings might not have been precisely as the book said, but like everything else I didn't cut corners and made sure to have the gaps away from eachother.

 

[YosemiteJeeper]

Did some things tonight...I cleaned that metal ground strap really good, took some sandpaper to where it mounts on the firewall. I also played with my multi-meter and got some info on my MAP, CTS, MAT, and TPS.
Manifold Absolute Pressure sensor: 4.04V on A+B and 4.94V on A+C terminals. It held vacuum too. On A+C it had 1888 ohms.
Coolant Temperature Sensor: cold, it read 1745 ohms.
Manifold Air Temperature sensor: cold, it read 1783 ohms.
Throttle Position Sensor: closed it read 914mv. At WOT it read 4.14V The book said 200mv/4.8V was spec...could this be my problem?

 

[cruiser54]

Did you reattach the 3 ground wires at the dipstick tube upon installation? If so, did you scrape off all the nice new paint so they made a good connection?

 

[YosemiteJeeper]

Yep. And I don't think paints going to be an issue on any block or head grounds...lol I'm pretty sure they're all good.

 

[Skreed]

Throttle Position Sensor: closed it read 914mv. At WOT it read 4.14V The book said 200mv/4.8V was spec...could this be my problem?

I dont think this would prevent it from starting just make it run like crap.

 

[Skreed]

I would go back to basics

Check for correct fuel pressure

Check for spark

Check for proper compression

Make sure your timing it correct.

Check all your fuses and relays

Make sure your battery voltage is up to snuff.

 

[HttpWayne]

Did you change any other parts outside of the engine block during this rebuild? Spark plugs, fuel injectors, fuel pump, coil, spark plugs/rotor/cap?

You only need 3 things to start (besides timing). Fuel, air and spark. If you have fuel pressure and of course you have air... that leaves spark. And spark is time sensitive. Also make sure you didn't get the fuel injector plugs criss crossed. I know those are very easy to mess up.

Did you put in a new cam? New cam means new lifters, and has to be broken in (after it starts of course).

WP~

 

[HttpWayne]

I dont think this would prevent it from starting just make it run like crap.

It may not be one problem. It may be multiple things compounding it. There could be the TPS, combine that with a set of criss crossed fuel injectors and add to that mis-gapped spark plugs or anything of that nature and you have numerous things stopping you. It doesn't have to be just one thing.

What was the purpose of the rebuild in the first place? Maybe this will shed light on to other problems that were pre-existing that instigated a "rebuild" that are STILL there, and now with a first time rebuilder rebuilding it there are more small problems that are preventing it from starting.

Just saying.

 

[YosemiteJeeper]

I only changed the plugs, but they are gapped right. The machine shop owner said I had a cracked head, so he gave me a new one and rebuilt that for me, said it was good. I labeled everything, the injector plugs are in order. Like I said, the fuel filter but that should help not hurt. I just checked my fuses and found some lighting circuits out, but I'm not sure about the relays I'll try to check them. Not too happy about buying a fuel and compression gauge, but if its a needed item I don't have much choice.

The reason for rebuild was age and wear. It had numerous problems like no oil pressure when warm, dead cylinder, knocking at 3K RPM and up, scraping sounds...Was just tired. 205K miles. I pulled it apart and man...you should've seen the bearings they were all torn up. Crank was gouged all around, cylinder walls were cut up, 3 pistons were scratched badly and 3 were different brand and looked almost new haha
So I had it bored .020 over, new internals, rebuilt head. Kept the cam and lifters, they looked pretty good still. I plan on replacing those with a mild aftermarket kit but I think I could get some time out of the old parts.

 

[Skreed]

So any chance you can take it to the shop who did the job and make them stand by their work?

 

[YosemiteJeeper]

If I can prove the head failed or the block is bad yes. Parts quality (I.E. hole in piston) is the only other way to pin it on anybody else hahaha I did the tear down and rebuild myself. I wanted to be proud driving through the streets knowing I fixed it. Its trying to start its just not catching. I'm going to do the compression test and fuel test. If I can't find anything useful from that I'll replace the TPS seeing as it is out of spec. If it affects running condition, why couldn't it be at least part of my problem now? I read some of the other threads and got some ideas so I'll check into them as well.

 

[HttpWayne]

... did the lifters, rods and rocker-arms go back in the same order they came out in?

Also, never use those platinums. They are garbage. I bought a set and had to return them and get new ones. This was at a time when I hadn't rebuilt the engine (was running fine before new plugs/wires/cap). After I started it up it sounded like it wanted to die. I put the old ones back in and it ran fine. Platinums just sound fancy in name.

 

[YosemiteJeeper]

Yep. I put them up labeled and organized and they went in the same way they came out. And I changed to champion coppers.

 

[cruiser54]

Search "distributor indexing". I'll bet your distributor is off a tooth or more.

 

[YosemiteJeeper]

Did a compression test and they were all from 120psi to 130-135psi. Fuel pressure was 35psi after double priming (NOT while cranking. Didn't do that). Put in a new Coolant Temp Sensor. Pulled the fuel rail, all injectors are firing...#4 wasn't at first and they seemed kind of oddly ordered at first, but after a little while they kicked on and looked great. Didn't see anything leaking. Broke the bolts loose on the CPS and tried to push it down. Ohms at the injectors were all 14.6-7. Opened up the ECM and cleaned the big contact bar out really good. Looked it over, some of the jelly-lookin stuff in there was cracking but didn't appear to be down to the board. Battery's sittin on a charger right now.

I'm thinking either the cam sensor, Air temp sensor, or maybe the TPS? It shouldn't be a timing thing, if it is its either the chain (F***) or shouldn't be big enough to cause this lack of response, it should at least give greater effort to start.
Its getting fuel, spark and air. They should be where they need to be at the right time. That why I think sensor, because something has to influence it to throw it off right? I could just have one of those uncooperative, "F*** you" kinda Jeeps lol

Ideas?

 

[cruiser54]

Yep. And I don't think paints going to be an issue on any block or head grounds...lol I'm pretty sure they're all good.

I just re-read your response. Are you saying you didn't paint the block and ther should be good contact there or that you doubt tht grounds attached to a painted block could cause your problem?

If you think grounds attached to a painted block would present no problem, you should be aware that the factory had a bulletin on these Jeeps when they were new advising the dealership techs to remove the grounds and scrape the stud to bare metal as a cure for elusive crank/no start problems.

 

[HttpWayne]

The thick kind of paint that is used to coat engine blocks degrades electrical connectivity more than you think. It's not the mico-thin layered paints that are on the body. It's thick acrylic meant to stand up to high heats. I'll gaurantee you if you have any layering of that on there that it's degrading your grounds.

Also, our engine isn't nearly as conductive as some others. It's cast iron, not aluminum. Aluminum engines are much more electrically conductive than our cast-irons. Add to that that high-heat engine paint. Some of your multimeter testings might be off just because of that alone.

I recommend scraping any paint in a grounded area.

 

[HttpWayne]

I re-read myself. You said you changed the CPS. Did you change the crank position sensor?

After I rebuilt my engine I had to replace the crank. It wouldn't fire up until I did that. It threw three codes related to transmission and crank position sensor. After I replaced the crank sensor it all went away and started up.

 

[HttpWayne]

Also, I was just thinking... you said you have spark? And you can smell fuel in the exhaust?

I don't see how all those sparks can miss the fuel unless they aren't numbered right. Either the fuel injectors or the plug wires. It's either that, improper timing, or you have to have a cracked ignition coil (like I did). Did you try swapping in a new coil? I don't remember you saying anything about that..

And/or the grounds are so degraded that it's the same as having a damaged coil. The weaker the ground, the weaker the flow of current through whatever is on the other end of that ground.