Hi guys,

Got an XJ6 3.2 Sport (1996) and on LPG.

The last time it was ran it was started on petrol then when warm switched to LPG and then eventually turned off, I came back to it later on and it won't start now.

I've checked the inertia switch which was fine, the petrol tank is full and it's in petrol mode, the battery is charged and it just turns over but doesn't fire. Rev counter registers 200rpm.

Anyone got any ideas what could be up?

 

Toxicvrs,

Welcome to the Jaguar Forums!

There are so many accounts of X300 no-starts that one of our members, aholbro1, created a thread to link to many of them. It would be worth your while to spend some time studying the threads collected in the first post of this thread:

https://www.jaguarforums.com/forum/x...ngines-120221/


Since your tach is reading 200 rpm while cranking, we'll assume the Engine Control Module (ECM) is happy with the signal from the Crankshaft Position Sensor (CKPS).

Since the only reported difference between the last time the car started and now is that the battery has been sitting in the car without being regularly recharged by the alternator, the first thing I would personally do would be to measure the battery voltage while cranking. If it drops much below 11V, the ECM will not trigger the ignition to fire. Even a battery that has just been fully charged may not be providing the necessary voltage and current to make the ECM happy at startup.

You can also check for 12V between the White/Pink wire at any ignition coil connector and a good ground, such as one of the engine bay ground studs.

You can disconnect the fuel hose from the firewall end of the fuel rail and briefly crank the engine to check for good fuel delivery (a clear plastic or glass container will help catch the petrol while allowing you to observe the stream).

You can pull a spark plug, reclip it in the coil, ground the threads of the plug and crank the engine to check for spark. You can test the coils with a simple Coil-on-plug spark tester like this:




Also, since we're a friendly group, please visit New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum and post an introduction so we can give you a proper welcome and so we can learn something about you and your Jag.

Cheers,

Don

 

Right I've been out on it again. The plugs were sparking but looked dry so I disconnected the firewall end fuel pipe and put it in a bottle and cranked the engine, no issues there either as fuel was nicely flowing into the bottle.

 

Hi Toxicvrs,

You don't mention that you've checked the battery voltage while cranking - that would still be my primary suspect.

You have spark and fuel at the rail, but it's possible the fuel pressure is low, or the injectors are not pulsing. You can check for a proper signal at the injector electrical connectors with an inexpensive noid light, or pull the fuel rail and injectors and crank the engine briefly to confirm the injectors are opening and are properly atomizing the fuel.

A common cause of low fuel pressure is failure of the Fuel Pressure Regulator (FPR), especially when the fuel check valve on top of the fuel tank has also failed. The FPR and check valve work together to maintain proper fuel pressure in the rail, but when they fail the fuel pump must supply sufficient constant pressure to keep the injectors atomizing the fuel, and a weak fuel pump may not be able to do so.

Another possibility is that your Camshaft Position Sensor (CMP) has failed. The ECM uses its signal to determine TDC of Cylinder 1 within the first revolution of the engine. From that point forward, the ECM uses the Crank Sensor (CKPS). Theoretically, even if your CMP has failed, the engine should start after 30 seconds of cranking or so. The ECM has to use trial and error to determine cylinder 1 TDC, so that's why it can take a while.

Don

 

Sorry I've not replied recently but it's been at a garage who've not done anything to it. All Coilpacks were reading up 11.9 / 12v on the White /cream coil pack wires. The battery is brand new and reading 13v before cranking and 10v when cranking, cylinder nearest the front has a weak spark but I couldn't see a spark on the other cylinders, plugs smelt petrolly it's got new plugs and has fault code P1621, what could be up?

 

P1621 - Engine control module engine immobilization input circuit malfunction

 

I know that but I've heard it can be a generic code that Jags can throw hence I was looking at the bigger picture. Has anyone got any ideas as I'm getting desperate and will scrap it otherwise

 

Long shot, but do you have compression- As you know, you need fuel, which you seem to have, spark, ditto, air, and compression, in the right amount at the right time. You can try cranking while introducing propane into the air intake and you should aat least get a fire or two.

 

I've sprayed easy start Into the air intake to no avail, a mate who works on funeral cars mentioned a dodgy throttle body, could this relate to a slightly high idle when we bought it?

 

Ohh yes I also removed ecu to check for corrosion, casing was bad but internally fine. Then checked crank position sensor, resistance was spot on.

 

But, as I understand your posts, you have spark, right? How did you test that?

 

Turned the engine over whilst holding the thread on one of the engine studs. Now working on fuel system as she tried to fire on a can of butane. Found leak in bottom of fuel rail, will get a new one. Is it worth replacing pressure regulator at the same time as I'll be getting injectors tested and cleaned too

 

Hi Toxicvrs and greetings from snowy Lake Michigan. USA
I have a 95 VDP with 128K miles that I recently obtained with same no start problems I think you have. I believe your fuel injectors are not being told to fire by ECU.

My vehicle will normally fire instantly with just a bump of the key when the outside ambient temperature is above 50 degrees Fahrenheit. Below that, it justs cranks and cranks with no start.

Here's what I want you to try and it won`t cost you anything. There are two temperature sensors and a relay that could be not talking with ECU to tell injectors to squirt.

You'll need a heat gun or even your wife's hair dryer for this trick.
On top middle or center of your intake runner is a small intake temperature sensor, on your thermostat housing is the other temperature sensor. They both send a signal to relay (not sure if in parallel or in series) to small fuse box located on top of front right fender wheel well.

Remove cover to this small fuse box and you'll see square relay. Apply heat to these 3 areas......you don't need much. I was just trying to get them to 60
ºF. WARNING! you mentioned fuel rail issues......make sure no fuel leaks before applying any heat. Once areas are warmed up, try to start. Varoom

Now this works for my vehicle. I have yet to correct this problem but it lets me move and drive the vehicle. I have also helped 2 other x300 owers who could not get their vehicles started using same method during our sudden Polar Vortex (early winter) even at 16ºF.

Being a new addition to my stable of 4 Benz`s I maintain, I'm looking forward to getting my x300 up and running. My guess is that the relay may have a cracked sodder joint that opens up when cold.

Give this a try .

 

So I fitted new fuel rail and pressure regulator, she fired up and kept running with a bit of help from easy start, she then ran and drove fine, turned it off and it wouldn't start again just kept cranking, so I sprayed easy start in and it fired again and ran. If I turn the engine back on after turning off within 2 minutes it still starts. Really getting desperate now.

 

Just pulled codes P1621
P0113
P0123
Could any of these affect it?

 

Hi Toxicvrs,

I haven't looked up your codes (easy enough to do yourself), but a battery that is sagging to 10V while cranking is a problem, and a frequent cause of random codes being tripped. As I mentioned in an earlier post, if the voltage sags too far below 11V while cranking, the ECM will not trigger the ignition to fire. Perhaps your coils are only firing intermittently due to low battery voltage while cranking. Have you tried boosting the Jag with another vehicle to increase the voltage while cranking?

Jag saloons need strong batteries, so it's possible it's time for a new one. But first I would suggest cleaning all the battery power connections at the battery, firewall, alternator and starter. Corrosion on those connections is a common cause of poor battery charging and starting.

Cheers,

Don

 

Brand new battery,
One is throttle body circuit a Voltage High, the other is an immob one which is still on even when I started it and wiped codes and took it for a drive. The other one is intake air temp.

 

Hi Toxicvrs,

Those codes are so unrelated from one another that I would definitely suspect low battery voltage, and the fact that your battery voltage is sagging to 10V while cranking is just not a good sign. Have you tried jump-starting the car with the boosting vehicle's engine running?

Don

 

Sorry, the battery voltage isn't an issue now, I forgot to say that in the last post it's cranking over at 12v, as it starts with easy start and then keeps running on petrol it's got to be a fuelling issue and I've been told it could be the intake air temp sensor that's causing these starting issues.

 

Forgot to update this, issue was that the TPS for some reason had been fitted 180 degrees out by a previous owner and as a result the car wouldn't start.