Hi, I am new here and I would appreciate some hints to solve my problem. I am an owner of a Xj40 Sovereign 1990 4,0 ltr engine. The car has been sitting in my garage since october last year. The garage is well ventilated and keeps about 18C all the time. When I tried to start the engine for the first time this year it wouldn´t fire. The battery is charged and it cranks fine, but the motor doesn´t fire up. It is dead. I have checked the spark and it´s ok. Must be the fuel then. (the tank is almost full) Is there an easy way to check the fuel pump/press?

/ Hans

 

Use the forum search function for hard or no start.

Have a look at this sequence of pictures showing how to connect a pressure tester to the XJ40:

Welcome to Jag-lovers - Members Photo Viewing Page

 

Hi Hans,

Welcome to the Jaguar Forums! It's great to have you with us.

Was the car running when it was parked in October, or was a no-start back then the reason it has not been driven since?

Have you checked all fuses in all three fuse boxes?

Have you checked the VCM for any stored Diagnostic Trouble Codes? To do so, turn the key to Position II (ON) but do not crank the engine. Press and release the VCM button on the trip computer to the right of the steering wheel. Watch the odometer/mileage indicator window for a message. DTCs are presented in the form of "Fuel Fail" or "FF" and a number. Write down any message you see and post it here and we'll try to help.

Is there any sign of rodent damage to any of the wiring in the engine bay?

Connecting a fuel pressure gauge to an XJ40 is not easy with most standard gauge kits. The photo at the link below shows how many fittings Bryan had to assemble in order to attach the gauge to the XJ40's existing fuel fittings:

Jaguar XJ40 Fuel Pressure Test Adapters - Bryan N

A simpler but helpful test is to disconnect the fuel hose from the inlet end of the fuel rail closest to the firewall/bulkhead. Aim the hose into a catch container, turn the key to Position II (ON) but don't crank the engine. The fuel pump should run for a few seconds to prime the system, and you should get at least a few ounces of fuel in your container. If you get very little fuel, try cranking the engine to see if the pump comes alive.

If you get no fuel, check the fuel pump relay, which is on the relay panel under/behind the glove box.

If you have fuel, perhaps your spark is weak. Low battery voltage while cranking is the most common cause. If the voltage falls much below 11 volts while cranking the ECM may not even trigger the ignition to fire This problem can be exacerbated by corrosion on the battery terminals, engine ground strap, battery ground connection to the body, or the battery power connections to the starter.

Another thing to check is the distributor. Disconnect the cap and check for moisture, tracking between the terminals, eroded electrodes or rotor tip, arcing down the distributor shaft, or a worn distributor shaft (check for side-to-side play). Also check the connections at the ignition coil and ignition amplifier (the small square component mounted on a metal plate beneath the coil).

A failing crankshaft position sensor (CPS) is a common cause of a crank-no-start condition. First, check to see if its electrical connector is contaminated with oil or if the sensor itself has a buildup of gunk.

Since the car has been in a garage, rainwater contamination of the fuel or ECM seem unlikely, but they are common problems in cars stored outdoors.

Leaking or clogged fuel injectors are a possibility, as is low cylinder compression.

Hopefully other members will offer additional ideas. Please keep us informed.

Cheers,

Don

 

No necessarily. You might see a spark coming from the plug but a bad distributor cap and/or wires might still prevent starting. I new member here experienced this when trying to get an XJ40 running. To check fuel pressure find the Schrader valve and ideally use a gauge but if you don't have one then stick something small and pointy into it and see if fuel squirts out. Have the key on to prime the system obviously.

 

Unfortunately the XJ40 has no Schrader valve..., thus all the adapters required as shown in Bryan's photo.

Cheers,

Don

 

Thanks for reply, I´ve tried to start it again today, and to my surprise it fired up for a brief moment. Just one or two seconds. It seems like it is running far too rich because when I removed the plugs and cranked it, it was like a fountain of fuel fog spraying through the spark plug holes.. ( when cranking the tachometer shows about 200 rpm) The injectors spray too much fuel into the heads. But why? Any hints?
/ Hans

 

Leaking fuel injectors could cause too much fuel in the cylinders and an over-rich, unignitable air-fuel ratio. To confirm this you would need to pull the fuel rail and injectors, mount them where you could observe their spray patterns, then activate the injectors, most easily by cranking the starter.

 

I don't know if this will help but I will throw it out there for what it's worth. This isn't a Jaguar, much less an XJ40, but one of my vehicles flooded its engine during the winter for whatever reason. It simply would not start and a mechanic came by and floored the pedal, cranked it, and it stumbled to life. He explained that when you floor the pedal it shuts off the fuel injectors.

Maybe first spit out as much fuel as you can out the spark plug holes and then try starting it normally and if it doesn't catch then try this. Just let go of the gas pedal as soon as it fires to not redline an engine that isn't up to operating temp. Best of luck.

 

If it REALLY is getting too much gas, maybe the fuel pressure regulator diaphragm has perished?

Larry