Jaguar xj 2.9 won't start no injection fuelpump not working
 

I bought an early 1986 XJ6 2.9 sohc as a restoration project. Was not running and stored for 17 years so I bought it with the idea that the fuel pump was broken but I tested the pump and it works fine, the pressure is good and the relay works (tested separately). I measured my compression and I have between 11,5bar - 12,3bar. My ignition, spark plugs are working, new crankshaft sensor, new throttle potentiometer but I'm not sure about my mass air flow sensor.
So i tested my injectors separately and they are working and I have over all 6 the same resistance of 16,2 ohm. But my injectors don't recive a pulse or signal to inject and its the same with my fuel pump.
One thing was strange on my first attempts to start: after the attempt I turned off the key, pulled it out of the contact I had 1 or 2 injectors still injecting (heard little clicks) so I pulled out he connector and plugged in again and it stopped. I had it a few times but it was never the same injector/injectors

(The engine reacts on startpilot and starts and runs until I stop spraying)
On my vcm I have a notice of brake failure but I don't think that tis could be the problem.

I found someone with the same problem but he is still searching.
Is there anyone with the same problem or that had the some problem?
Thanks in advance

Not too many 2.9 litre XJ40's. I had one and went through a non-start issue on a few occasions.

The crankshaft sensor is even more unreliable than the one on the twin cam engine and, as I recall, about three times the cost. However, if you have definitely eliminated this as a possible cause, the next likely culprits are one of the ECU’s (two on the 2.9 - one for ignition and the other for fuel injection).

Graham

I think there was a thread not too long ago about an issue with the ignition switch and that car (even though it was a 4 litre) had similar problems. He too replaced everything chasing it down.

Maybe the weird behavior when you pulled out the key is a clue?

I'll see if I can find the thread and post back

Larry

Here it is - solved in post 18
https://www.jaguarforums.com/forum/x...-start-211110/

Cheers

Larry

Hi Yves,

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

If I understand correctly, the engine will start and run when you inject Start Pilot into the intake. This certainly suggests a problem with fuel delivery.

Assuming your fuel pump really is working properly, could the fuel filter be clogged? Could the fuel be contaminated with water that has condensed in the tank while the car sat, or drained into the tank via the filler neck if the drain in the rubber gaiter around the filler became clogged with leaves and seeds and allowed water to pool around the filler?

To test the fuel pump and circuit:

1. Turn the key to position II (ON) but do not start the engine. Listen for the fuel pump to run for a few seconds to prime the fuel rail. The pump is mounted on the rear subframe to the left of the differential.

2. The pump priming burst can be difficult to hear. Another test is to disconnect the fuel hose from the inlet of the fuel rail (the end nearest the firewall/bulkhead), aim the hose into a suitable catch container, turn the key to position II (ON) but do not start the engine. Turn the key off after a few seconds, and check to see if there is fuel in the catch container from the pump's priming burst. If little or no fuel is present, crank the engine briefly, then check again for fuel in the container. If little or no fuel has been sprayed into the container, the pump is not being energized.

3. I'm not certain if the 2.9L circuitry is the same, but on the 3.6L cars the fuel pump motor receives its power from a splice directly into the positive battery cable, and the circuit is completed via the fuel pump relay load contacts. This circuit also passes through the oxygen sensor heater and is grounded at the intake manifold #2 cylinder stud. An open O2S heater coil will prevent the pump from running, and corrosion or looseness of that intake manifold ground can interfere with proper pump operation. The fuel pump motor is grounded at the left A-pillar ground post (at least on LHD cars), and that ground must also be clean and tight. The other critical component is the Main Relay, but since your engine will run on starting fluid I would assume that relay is engergizing properly until other suspects are ruled out.

Regarding the Crankshaft Position Sensor (CPS), I would also assume it is working since the engine runs on starting fluid, but a quick confirmation the the CPS is probably working is to watch the tachometer/rev counter while cranking the engine - it should read about 200 rpm. If it reads 0 rpm, suspect a problem with the CPS, its electrical connector (pins have been known to back out of the housing and not make good contact), or the wiring harness, which is prone to damage from age and heat or from rubbing on rotating components if not properly secured.

You can test for battery voltage at the pump electrical connector and work your way upstream from there. The schematics for the 3.6L cars can be downloaded at the links below. The fuel pump circuit is on the Engine Management pages near the back of the manual:

Jaguar XJ40 Electrical Guide 1988

Jaguar XJ40 Electrical Guide 1989

When you have a chance, please visit the New Member Area - Intro a MUST and post an introduction so we can give you a proper welcome.

Cheers,

Don

all my injector are injecting at the same time
 

Everybody thanks for the answers, this weekend tested a few things again. First I cleaned all my plugs, contacts and made new mass wiring and cleaned all the contact points ( on the battery, inletmanifold, body, ignition coil, inside... everywhere I found a contact) . I have no oxygen sensor or lamba cause its a non catalyst

so I did a hard reset on the car + and - connected for a few hours and than I tried to start. I made a good mass connection from th engine to my battery and the plate where the two ecu's are screwed on to my battery. My fuel pump has still no command so I placed a switch in between. when starting my engine It was almost gone and I smelled fuel in the exhaust. So to be sure I took off my fuel rail with the injectors on it and cracked the engine to see if they work.

Injectors are working fine, fuel pressure is good but all my 6 injectors where injecting at the same time... I stopped cranking (the key in ignition on position) and they where still injecting, turned the key off and took it out and all the 6 injectors where still injecting. To let them stop I took of the - of the battery and put it back on and it was over, tried again to crank but with the key in ignition on all my 6 injectors were injecting again all at the same time. so ignition off and they stopped now, ignition back on and nothing, cracking the engine again nothing, no injection.

I took off the - for a time and removed my extra mass cables and tried the whole procedure again. ignition on and they where injection again all 6, same while cranking and it only stopped by removing the - from the battery. I put it back on and again nothing, no injection in the ignition on position or while cranking.
Could it be that there is something seriously wrong with my ecu?

Thanks in advance

Yves, take a look at this article - your engine is an AJ6 that shares installations with some 6-cylinder XJS cars. I believe the AJ6 is a multi-port motor but the article will tell you more about the injection system than you ever need to know!

Electronic Fuel Injection

PS - try cleaning the main ECU connection plug if you haven't already - (still thinking ignition switch may be duff though)

pps - one thing I got from a quick scan of that article was that fuel delivery was based on manifold pressure so maybe with zero pressure (injectors out) then ....

Larry

Hi Yves,

The way the injector circuits work is that whenever the key ignition is in position II (ON or RUN), all six injectors have battery/alternator voltage on their White wire with Brown tracer line (color code WN on the schematics). To open injectors, the ECM grounds the injectors' other wire. The injector ground wires are connected in pairs. The ground wires for Cylinders 1 and 2 are Pink/Black (PB), for Cylinders 3 and 4 are Pink/Blue (PU), and for Cylinders 5 and 6 are Pink/Orange (PO),

If the injectors are truly operating constantly with no pulsation, I wonder if all three injector ground wires are shorted to ground somewhere? The fact that they remain open with the key out of the car could indicate a problem with your ignition switch, but even if the switch is remaining connected to a ground circuit when it is off, I don't know how that could allow all six injectors to remain open. You might study the Engine Management schematic in the Electrical Guide I linked to in my earlier post.

Cheers,

Don

Everybody thanks for the help, meanwhile after checking and measuring every wire I found the issue on my 2.9 . The throttle position sensor was short, maf sensor broken and also the injection ecu. Replaced al those parts and it did start again.
There are differences between the ecu's of the early 2.9's and the models from 1988.
I got an ecu of a '89 model but to get it run properly I had to replace the temperature sensor on the thermostat housing (early models have a black one later models a green one).
Also had the upper timing tensioner broken so replaced all the tensioners and did a cilinder head rebuild. Replaced the head gasket just in time as well, very hard to find a 2.9 head gasket.
Meanwhile its back on the road again for a while now.

Cheers,
Yves