I'm watching the other thread about a no-start, but I've got a little farther (I think) in diagnostics. This is a 1984 XJ6 Series III, Federal (California, if that matters).

Car was running okay but extremely low on fuel. I had driven to a store, went in, came back out and no start. Thought I'd run it out of gas (both tanks) so I walked to the gas station, put a gallon in each tank. No start on multiple attempts on each tank. Had the car towed home.

I added another couple gallons into each tank. Still no start.

Thought maybe I'd plugged the fuel filter from debris in the bottom of the tank, so replaced the filter with a new one. No start.

I've got fuel pressure in the line at the filter (sprayed gas everywhere). I've got fuel pressure at the rail under the hood (sprayed gas everywhere).

I've got spark at the plugs (verfied).

The inertial cut-off switch is set properly.

I put a NOID light on one of the injectors and did NOT see a pulse.

I've got a strong crank, and it keeps sounding like it's just ready to catch and then dies. It's not just an endless cranking.

Is there something that would keep all the injectors from pulsing? That's the only thing I can think of now that might be the problem.

Thanks in advance,
-James
1984 VDP S3 Federal

 

Hi James, I assume this is a 4.2 motor? If so, check the bunch of earth wires at the back of the head. They need to be clean and they need a good connection to the head. Also try connecting and disconnecting the bullet connector that runs along the head with the ignition on and a Noid connected to any of the injector plugs, that should confirm if the injectors are indeed not firing. They maybe clogged and need a clean. Also the resistor pack plugs may just need a clean and reseat. This is a silver looking box in the front down low near the radiator support panel.
Con

 

Squirt some ether into the throttle body and crank. it may run for just a moment. If so, it is a fueling issue.

No noid signal at an injector signifies a fuel issue

Detritus got to the injectors. Perhaps. Remove and clean.

 

The fuel injection driven by the ECU in the trunk will not send pulses to the fuel injectors unless it gets a pulse off the ignition system. Yes, a single wire connection going bad can stop the system working ! The injectors receive a constant 12v and the ECU earths them all twice per engine revolution to pulse them. The time the injectors are earthed varies the fuel injected. A resistor pack is placed intermediately between injectors and the ECU to prvent damage in case of a short.

 

Thank you to everyone who took the time to reply. I appreciate it.

If I put the key into the RUN position (the next position cranks the engine), should I be hearing the fuel pump run? I just pulled everything out of the trunk (boot), including the spare, left the lid open and put the key in RUN--I don't hear the pump running. Should I hear that, or am I mistaken?

If the pump should be running, then I take it the next step is checking the fuse and relay?

(Sorry if this is elementary--but I haven't done much with the fuel side of things before, and my resident expert passed away).

 

I am sure if you put the transmission in drive and turn your ignition on the fuel pump will run

 

I had the same issue with fuel tank problems and ignition problems recently,I cleaned both fuel tanks out and I ended up replacing the high energy unit in the ignition amplifier and installed a new set of ignition leads.Car running great now.You can read my right up on jag-lovers forum.

 

Thanks, I'll check that out (your other posts).

I just put the key in Position 3 (run), gear in D, and not a peep from the trunk. (Engine still cranks, so I have battery power). Looks like I lost the fuel pump, or at least lost power to it. Gotta get the books out again.

 

Jaguar schematic S57. A must for any DIY jag guy. Where to probe for power.

ID the fuel pump relay. Probe for power there . The schematic will if the trigger circuit nd the load circuit.

Did you do the ether thing? Result ?.

 

I don't have access to ether. I bought a bottle of starting fluid from the auto parts store. Made a lot more noise but still no-start.

I'm checking the relays next, and as you say, whether there's power to them. I do have the electrical book.

 

This diagram is helpful in looking for wiring issues in fuel pump circuit... Definitely confirm that the 6 ground wires ("AT ENGINE") at back of intake/water manifold are clean and you have good ground between Engine/Transmission and body (Right Side behind and lower than starter motor)
Rgds
David

 

Thank you, David. That will be next on my list.

I pulled the diode pack and the two relays on the firewall--all test okay. (Also tested them against spares that I had.) I put the key in position 3 and thought I should see 12V on the main and fuel-pump relay sockets: no.

Still in position 3, looked for 12v directly at the fuel pump. No.

I do have cabin lights, window power, door locks, etc., so it's not like everything's dead.

 

Hi James

Good luck You are hot on the trail. Please post at the end the solution/fix. So many debug threads end up with no statement of what fixed the issue

Thanks - Randy

 

Starting fluid is ether.....

What noise???

 

James
It looks like you may have a fuel pump problem. My son and i have owned a number of S3 XJ6 cars over the 30 odd years since I bought my first one. The fuel pumps in these cars are very susceptible to failure from contamination typically from rust flakes and other grunge from the fuel tank. This seems to occur when the fuel tank is low for some reason but the physics are beyond me. Perhaps more sloshing around with low fuel levels stirring up contaminants in the in the bottom of the tank. Think how surf develops from gentle waves while deep, to breakers as the water shallows.

I also suspect from previous remarks on this post that there may be a misunderstanding about when and how the fuel pump will run.

To test the pump put the gear selector in any position barring the Park and Neutral. Open the boot lid to hear the pump run. Then turn the ignition key all the way to Start. The starter motor will not run due to the inhibitor switch system but the fuel pump should run. I have used this on a number of occasions to get fresh fuel into the system when getting fuel vaporisation in my tropical climates on a very hot day.

If you can't hear the pump run then you may have one of two problems. (1) lack of power to the pump ( very unusual) (2) an unserviceable pump due to contamination and blockage.(very common)

In the case of a contaminated pump it may be possible to clear the pump. Remove the pump from the car. Hook up tubing to the intake and outlet system. Hook up wires in reverse polarity so the negative battery is connected to the positive on the pump and positive to the ground.. immerse the pump outlet tube (now to be the inlet )in any fluid including petrol, diesel, turps etc but not water. There is a 50% chance that he pump will run in reverse and blow itself clean. Otherwise you are up for a new pump.

By the way, this is not the holy grail as we did have a case of a fuel pump running but no pressure. These pumps may have shear pressure failure when the pump jams and the motor breaks free.

In the case of possibly lack of power to the pump a simple 12 volt trouble lamp or a multimeter should be able to test the system at the power attachment to the pump.

I urge you to insert a filter in the fuel line between the fuel tank and the fuel pump. I have fitted my current S 3 XJ6 with this ten years ago and I still get surprising amounts of grunge in the filter although it is garaged in good conditions.

The only other solution I can offer is that I have seen a friend battle with a poor starting S3 which turned out to be a crook battery dragging down the volts where the injectors would not activate.

Bill Mac
MK1
MK2
S3XJ6
X300
Previous 14 jags. MK5 to X308
Current
Ford falcon Ute
Mitsubishi Colt shopping trolley
Subaru (tow vehicle for my aeroplane)

 

Thanks, I had never heard it called ether. I assumed it was something like kerosene.

The sound was a brief "roar", as best as I can describe it.

 

Thank you, Bill. That's extremely helpful.

This is made unnecessarily complicated by being alone--don't have anyone to turn the key while I'm in the trunk fiddling. I did try your suggestion (car in gear, key to crank) and thought I could kind of make out the fuel pump. Decided I'd try it there and used a power supply to put 12V on it while I'm standing over it--got kind of a sluggish response. Removed it and the intake side looked gunked. Gas coming out of the intake hose looked clean.

I had another fuel pump on the shelf so I put 12V on it and verified what it should sound like (steady whirr), so I swapped them out. The old pump (out of the car) seems okay now when I test it on my bench, but I'll make up a rig and run some cleaner through it.

Now stuck because of an unrelated problem involving the MAF sensor that I have to deal with, then I can button it up and try again.

Thanks again. I'll post again when I've made some progress.


Unrelated: interesting to see you have a Mark 1. I had a chance to get one once but couldn't justify it--it's all I've been able to manage to keep my XJ6 going, and it still needs a ton of stuff. But still, would have been to have. There's precious little that I've seen about them. Almost everything is Mark 2 and the original S-type.

 

James O
Please don't install the new pump without putting a filter in the line between the fuel tank and the pump.
While you are onto this problem have you checked the drain holes adjacent to the fuel filler caps?
The number of XJ6 cars with rust and crud problems caused by water getting into the fuel tanks, which is a result of blocked drain holes, is almost legendary.
I have owned Series 1,2&3 XJs and have found this problem in all of the cars
I would also like to suggest that you drain both tanks to see what comes out. Almost for sure you will get rust and assorted rubbish.
Re.The Mk1; I live on a property of 3 acres and have 9 undercover spaces for cars. Consequently I can take my time to restore a car. The current 2.4 manual with the SU carby modification (which is a Jaguar approved modification) is the fifth MK1 I have restored in the last 37 years.
Cheers
Bill Mac
MK1
MK2
S3XJ6
X300
Previous 14 jags. MK5 to X308
Current
Ford falcon Ute
Mitsubishi Colt shopping trolley
Subaru (tow vehicle for my aeroplane)
Bill Mac

 

Bill,

Where are the "the drain holes adjacent to the fuel filler caps?" The fuel filler caps on the top of each fender? I'm not seeing what you referring to.

I will add the pre-filter, that's a good idea. I will drain the tanks. Right now my immediate goal is to get the car into my garage where I can work on it easily and out of the sun and eyes of the neighborhood. I'm sure code enforcement will ding me working on my car in the driveway if they catch me (I used to live in a town where you're supposed to work on it in your own garage, either. I don't know if that's true here or not. I wouldn't be completely surprised).

Replacement pump clean and installed. I definitely have pressure at the fuel rail and the fuel is clean. Still won't catch. NOID lights not flashing. Makes me think the injectors aren't firing.

I checked every plug and grounds I could find--everything looks tight and normal.

Looking at the schematic, which David conveniently posted, I take it the next step is to find and check the resistor pack for opens, though I doubt they'd all blow at once.

Edit: found another thread that goes into more detail about the electronics involved. Tomorrow I'll get the meter and see if I can eliminate more causes.

 

James
Open the fuel cap as if you are going to fill the car and there should be a drain hole adjacent to the filler pipe.
If this is blocked water will accumulate in the area around the filler pipe and eventually find its way into the fuel tank.
Cheers
Bill Mac