98 XJ no fuel after rebuild.

Alright, I recently picked up a 98 XJ with a broken piston on the 4.0 at just over 200k. I rebuilt the motor and now it's not trying to start. Check cam timing, dizzy timing, all plugs, 100% spot on. The motor isn't even trying to start at this point, no sputter, cough, pop back, or anything else. Throw a timing light on it, no spark. Okay. Brand new cps. Cleaned out the connector and checked the cps with an ohm meter. Now have spark. Try again, and still no start, no cough, no bobble, nothing. Alright, cleaned all the grounds, nothing. Next fuel pressure. Pump was just replaced and line pressure is ~50psi at the rail. Injectors are not firing. Check voltage at the injector. Nothing. Grab a handful of asd's and another pcm from a wrecked 98 xj at the jy, tried all of them, and tried the different pcm. Nothing. Checked G101,102,103: cleaned. Nothing. Went through the faq and several threads and there's nothing I can find to even make this motor sputter on the starter. I'm at wit's end with this one, I'll be honest.


Tl;Dr: feel like I've tried nearly everything. No start secondary to no injector firing.

Bullet points for you actionable information types:
Things I have replaced:
-Engine, new rebuild, verified engine timing and correct dizzy orientation
-CPS, new
-Fuel pump, new
-ASD, attempted multiple other ASD's
-Attempted second JY pcm that appeared to be running when that 98 xj met its demise
-new cap, wires, rotor, oem plugs, all verified to have correct timing
-new battery
-new coil

Things I have cleaned and verified:
-injector plugs
-cps plug
-o2 sensor plug
-g101, 102, 103
-no blown fuses, no corroded fuse contacts
-50psi rail pressure
-read naxja faq + relevant threads via search

Problems I'm still having:
-No start, cough, sputter, or pop back
-no b+ at injectors
-no injector firing
-out of relevant naxja threads.

Vehicle was supposedly running without issue when it cracked a piston skirt.

When you say "CPS" are you referring to the Camshaft position sensor? Because "CPS" can also be the Crankshaft position sensor, which would fit your symptoms to a perfect tee as mine had done the exact same thing and was the result of a crank position center... The cam position sensor is located in the distributor under the cap, the crank position sensor is below the jeep on the bell

If thats not the case then by process of elimination theres only so many things that could go wrong. There is a slight chance it could be a wiring issue for the injectors but 9/10 times its the circuit being cut out due to failure of another component

Crank sensor is new. Cam sensor is old.

This situation isn't making a lot of sense. No power to the injectors, but the fuel pump works? Usually when the ASD relay is open, so is the fuel pump relay except to prime the fuel rail for few seconds when the key is turned to run.

Are you getting any spark? If no it is likely a sensor issue.

Is the fuel pump relay closing while the engine is cranking over?

Any power to the dark green and orange power wire for the injectors while the engine is cranking over? They all share the same power source, the PCM pulses them on the ground side.

If a sensor is causing the issues, you should have a code. Though there are exceptions.

Maybe check the orange wire going to the CPS for 5 volts (usually 5, depends on the year) keep it connected for the volt test. That same 5 volt power supply is for the MAP also, no power to the MAP, no reference signal, no ASD relay. That same 5 volts goes to the Cam Position Sensor also. It is possible for that 5 volt power supply to short out and cause bus failure, which may not throw a code, but will shut down the ASD relay (injectors) and also shut down the fuel pump relay. All you will get is a prime, no fuel pump while cranking and no spark.

Best guess is you plugged a connector in wrong, I believe there are two that can be crossed up (I may be wrong about this and confusing it with another year). A pin backed out of a connector or a pin got bent in a connector. Oil in a connector can also be an issue.

I once put a motor in and clamped a wire between the motor and the bell housing. Not that big of a deal, just embarrassing.

Re: Re: 98 XJ no fuel after rebuild.

8Mud said:

This situation isn't making a lot of sense.

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It's got me stumped, that's for sure.

8Mud said:

No power to the injectors, but the fuel pump works?

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Yes

8Mud said:

Are you getting any spark?

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Yes

8Mud said:

Is the fuel pump relay closing while the engine is cranking over?

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Not sure, I'll check

8Mud said:

Any power to the dark green and orange power wire for the injectors while the engine is cranking over? They all share the same power source, the PCM pulses them on the ground side.

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I'll check that too

8Mud said:

If a sensor is causing the issues, you should have a code. Though there are exceptions.

Click to expand...

No code unfortunately

8Mud said:

Maybe check the orange wire going to the CPS for 5 volts (usually 5, depends on the year) keep it connected for the volt test. That same 5 volt power supply is for the MAP also, no power to the MAP, no reference signal, no ASD relay. That same 5 volts goes to the Cam Position Sensor also. It is possible for that 5 volt power supply to short out and cause bus failure, which may not throw a code, but will shut down the ASD relay (injectors) and also shut down the fuel pump relay. All you will get is a prime, no fuel pump while cranking and no spark.

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Have spark, all sensors read 5.3v at the plug.

8Mud said:

Best guess is you plugged a connector in wrong, I believe there are two that can be crossed up (I may be wrong about this and confusing it with another year). A pin backed out of a connector or a pin got bent in a connector. Oil in a connector can also be an issue.

Click to expand...

I thought so as well but I cleaned and checked them all two days ago

8Mud said:

I once put a motor in and clamped a wire between the motor and the bell housing. Not that big of a deal, just embarrassing.

Click to expand...

I've been at this for two weeks now so I'd be relieved if it was just me being tarded.

I haven't figured out every possible programming scenario, but if the 98 is like some of the earlier models (likely) if the MAP isn't plugged in or there is an ope circuit for the MAP the PCM gets no reference signal (atmospheric pressure) and refuses to fire the injectors. This may or may not be fact for the 98, but the programming in the PCM, is much like windows, they add lines of code over the years, but keep the basic program.

There used to be to be two connectors near the fuel rail and the TB that kind of fit together. What I'm saying is it may be possible to cross the two connectors. I'm not remembering exactly which two, maybe the manifold temp. sensor and something else. It is likely they changed these connectors in later models, but seeing as we are grasping at straws here, it may be worth a look.

I don't have a schematic for the 98, but on many models the ASD supplies power to the coil, the alternator and I'm pretty sure the injectors. If one is getting power and the others aren't it is likely to be a connection, fuse or a broken wire. Dark Green and Orange wire on earlier models.

Power wire was broken in the insulation. Little splice and it runs like a top! Thanks all

So a new problem has popped up. Now, the engine runs fine cold. But once the engine gets to temp, it pops back hard through the throttle body and will not rev past 2000RPM. I've verified the timing to be 100%on and dizzy timing to be correct. No noted vacuum leaks. Temp sensor is new and gage is working as intended.