Hi all, just got my Jag back from the garage. It was in for thermostat housing gasket, alternator belt and exhaust welding so took her home no probs (very short journey). The other day on a short journey rpms dropped a few times but I thought it was because of incline and reserve fuel level combo so I've put some fuel in. Today it won't start. It cranks and it's almost stating but not exactly. Any ideas what should I be looking for?

 

Almost starting as a few combustion events in the cylinders indicate you have 2 relays closing or somewhat closing

Ignition positive relay in the corner of the right engine bay fuse box ,this is your engine ECU first power

ECU control relay as a large right # 5 , this is your second power to the ECU and direct power to the injectors

First try would be to directly power the fuel pump by umpering the socket 3 to 5

Pics coming

Just fill with gas that can be bad ?

 

hi, cloud you please clarify/simplify "First try would be to directly power the fuel pump by umpering the socket 3 to 5"?

Fuel is good but I think they might have welded the exhaust with engine running as that explains the low fuel after that although I specifically told them to disconnect the battery, so could the welder fry them relays? Also, car just started after the 10 attempt but rpm still drop every now and then and I'm really not confident it will start tomorrow.

 

Do you have a CEL code P0335 as the CKPS is used in fuel pump enable and ignition timing

You may not have any check engine light

 

Specifically to your fuel level observation the sender is powered through the instrument cluster through a couple of fuses in the left heelboard fuse box where some of the fuses require that relay in the corner be closed

Fuse # 5 / 10 amp and # 12 / 5 amp left heel board fuse box is for the instument cluster .......................and # 16 / 5 amp trunk fuse box for the instrument cluster.

Fuse # 1 - 9 are hot at all times directly wired to the battery inside the fuse box bypassing the relay in the corner

Fuse # 10 ,12, 14 , and 16 require the corner relay to close

Then the remainder of the fuses are directly wired to the battery

The fuel pump relay " control " power comes from fuse # 10 / 5 amp in the right heel board fuse box

The fuel level sender has a ground on the side of the battery that may have been disturbed as the ground stud bolt goes through the trunk sheet metal

So you have a no start 10 times

To test the king relays in the corner of the fuse boxes have the ignition key in the run position but engine not running

Remove the king relay in the corner of the fuse boxes and you should feel them click in your finger back to the open position

A swapping option is the relay in the corner of the left engine bay fuse box as in reality this only controls the car horn

 

Error

 

One lesson I learned a long time ago is that you should never let your fuel level drop below a quarter of a tank. The fuel in the tank helps cool the fuel pump, and when you run your tank down to the reserve levels, the pump itself is uncovered, and can heat up, causing premature death, seeing as you had a problem as you were going up an incline and you were close to reserve. Sounds like your pump was not covered and it could’ve been the straw that broke the camels back. Try measuring your fuel pump pressure during cranking and see what you got.

 

Fuel pressure 43 psi but is not easy to check because of te fuel line fittings on the X300

 

"Jumpering"... Putting a jumper wire between terminals 3 and 5 in the fuel pump relay socket, the brown relay labeled #1 in the photo (yours may be blue). This would bypass the ECU control and give power to the fuel pump continuously. Then try to crank. The relay socket is green.

Parker mentioned the CKPS is a common age-related failure point and all cars should get a new one of these. It is the sensor visible at the front of the engine that reads the crank pulley notches. It is critical to ignition and fueling. It can go intermittent, often without the corresponding fault code, and could cause all kinds of running problems.

Is your camshaft dizzy tightened down? It is the round item at the front right of the engine that used to be a distrubutor. It should not rotate. A very slight turn of this device will cause very difficult starting.

I sure hope they didn't weld on your car with the engine running! That could fry every electronic in the car. Maybe instead they just used your car (and fuel) to run some errands after they did the work! After all, everyone wants to drive a Jag.

 

When you picked up your Jaguar where the 2 mechanics wearing ascots trying to out funny each other as they talked that way

 

Current update - charged the battery fully overnight and started straight away. Drive down the oeteols station trouble free and put half a tank of Premium. On my way home engine cut off at 30mph and battery warning was illuminated in the dash. I started the engine straight away while in motion so went home ok. Going to the garage in Monday to see if the 1 year old alternator is gone or the battery is beyond saving. Halfords branded battery...

 

In the heat of battle be sure to not put the battery in backwards , ask me how I know

I put a peace of tape on it pointing fwd as the positive post goes in the direction of positive / fwd car travel

Do not over tighten the battery positive post bolt as breaks the special nut underneath

More on your observations later after morning tea

Do you have an electrical meter ?

Do you have a 3.2 liter or 4.0 liter normaly asperted engine ?

I'm going to put up a print of the 4.0 version of the charging / starter circuit up and your charging section ( as the red colored battery cable wire around the border ) is the same just you don't have an issue with your starting section

Your engine stalled but started right up meaning your's has a adequately charged battery so we'll look at some battery cable connections from the front alternator to the battery

There are 4 terminal points

Your alternator charge light might have come on before or after the engine stall

ask questions

 

Back to your original post observations with the drop in RPMs

Without changing the crankshaft position sensor did you swap the 2 relays that power the engine ECU ?

Small right engine bay fuse box relay # 9 ( called the ignition positive relay ) and large enginne ECU controlled relay right # 5

The large engine ECU controlled relay can be stuck from removing from the socket by a waterproofing O- ring and some penetrating oil spray helps to loosen once flipped upside down to expose the seam

The relay removes from the car mounting bracket by either lifting up or pushing down to unclip from the car

 

CKPS: Crankshaft Position Sensor. Get a new one.

 

You can obtain a crankshaft position sensor from the local auto parts store as it is common and generic and doesn.t have to come from a Jaguar parts vendor to save some money

 

New crankshaft position sensor fixed the issue so I put an Andy bracket while I was there. All good now. Funny enough that sensor was just 1 year old and already dead. It was £23 unbranded one from ebay though. Thanks all for the support!

 

If you get stranded and your resolution seems to have been the CKPS the direct heavy gauge wire jumper Ing of the fuel pump relay between 3 and 5 may get you home

So a made up jumper wire sitting in the trunk or a spare CKPS is sometimes kept