My 2004 XJ8 (DOB April '03, G07248) has been surging when at a steady low speed from once it came off the initial settings until it was thoroughly warmed up. I've been living with it but now it won't start. Otherwise it was running smooth and strong. It has a good spark and ether didn't help. Pulled two DTC codes, P0335 and P0117. Replaced the crankshaft position sensor and the engine coolant temperature sensor. No change. The fuel rail has 40 psi with ignition on and it rapidly fluctuates from 40 to 50 while cranking.
I'd like to pursue the likely and easy to check possible faults first but since it was running strong and I have good spark and fuel pressure, I don't see a likely culprit. The service manual lists the purge valve as possible cause of not starting but it is hard to imagine it could have this much impact.
Am I correct in assuming there is no chance of additional DTC's without the engine running?
What would you do next?

 

Based on your description, the first thing that occurs to me is that maybe the injectors aren't delivering fuel. Have you checked the plugs for wet fuel? If they are dry, then it seems you aren't getting fuel to the combustion chamber despite good pressure at the rail.

 

Indicated fuel pressure is too low.

Check fuel sensor vac connection for cracks.

 

What should the fuel rail pressure be?

 

like 50psi. it’s enough that’s not your problem

are your injectors firing?

 

After cranking, I pulled a plug and it was wet with gas.
The rubber hose between the fuel rail pressure sensor and the throttle body housing is in good supple condition. Is this the hose that could be an issue?
With gas and spark I can't believe I can't even get a backfire.
The car was running great.

 

hold the pedal down for 30 seconds and let go it may catch

a bad coolant temp sensor will flood the engine and you lose all compression, check the readout. you may have to add oil to the cylinders manually

 

I checked one cylinder's compression and it was 100 psi and the gage got wet with gas. Not great compression but I would think it should fire. Does this car have Nikasil cylinders? The car has 157K miles. Ether usual will get a worn engine to fire. It uses no oil and keeps its oil clean.
I'm confused about holding the pedal down in this car as its "fly by wire" and I have no direct control of the throttle plate. The cylinders are getting flooded but they should dry out by the next day and this no start is days old. I'll try the pedal down and crank
The tach doesn't move during cranking but I don't know that it ever did. If anything it drops below zero a bit. Does this have any meaning?

 

foot to floor is programmed for fuel cut. flooded cylinders can happen with iron or nikasil it doesn’t matter

tach does not move on this car

 

I tried the pedal down and cranking approach. After 10 seconds it caught, sounded good and idled. Only thing is the serpentine belt was squealing and smoking. After a few seconds the squealing and smoking stopped and the engine sounded good but the low oil pressure light and alternator light came on. The alternator wasn't a big surprise with the belt's issues but with the oil pressure light on, I shut it down. The serpentine was off the pulleys. The oil was full so I tried to restart it but it wouldn't restart with a quick effort.
I'll start again tomorrow. Something driven by the belt must have seized but how do all these issues connect ????

 

The alternator is seized. The car sat unused with a trickle charger for 3 month before this no start problem.

 

Sorry, Rick. At least you found the problem.

I bought my XJ8 after it had sat for more than 6 months due to failed rear air shocks. A/C was not working when I first checked the car out. I later discovered that the compressor had seized. My Range Rover classic Tdi has been sitting for about a month. I better go drive it around...

 

Do you know what caused the alternator to seize?

An electrical fault?

 

I'm removing the alternator now. It seized while the car was idle for 3 months in the garage with a trickle charger. It looks weathered but was making no noise before being parked. Do you have a suspicion what happened?

 

Was it the garage with a car cover? Most likely the moisture is being trapped in the engine compartment.

 

"Do you have a suspicion what happened?"


No idea. Pls let us know what you find.

 

Covers can cause a lot of condensation issues

 

I replaced the alternator. There is a very good YouTube for it. Then the starter was dead, not even a click. Test light said power to lug and power to solenoid with key turned. Replaced starter. Nothing. Test light said I had both powers to new starter. Only thing required to complete the circuit is the engine ground strap. I noticed if I used the ground strap to ground the test light I got a slightly less bright test light then using chassis. Cleaned the lug on the ground strap and she started right up and ran great. This bad engine ground is the likely cause of not starting, the DTCs, seized alternator and faulty starter action. Cars with the battery up front ground it to the block where by far the largest amperage draw will be and have a little chassis ground strap for everything but the starter. Grounds to aluminum can form a thin white oxide insulating barrier. This fix has been brutal.

 

Glad you got her cranked up! It is a great feeling when a frustrating problem is licked.

 

Will clean the ground strap on mine next I am working on it. Cleaned lugs by radiator and behind backseat already.