I grounded the orange wire at the fuel pump (relay). It appeared that the pump would run continuously.
Still didn't start... back to the spark on the assumption it's not strong enough. I guess I'll start with the power modules.

 

I think you should also test that the injectors are actually spraying fuel, and not just clicking. I would do this next, so if you move on to the ignition, you are 100% certain fuel is getting into the cylinder.

 

Hi Mike

It could still be a Fuel Problem

If you have got the Car outside and can undo the Fuel Pipe from the Fuel Pressure Regulator on 'B' Bank and can slip a hose over that Pipe with the other end hanging over the side of the Wing/Fender into a Can

You could try that 'Orange Wire Trick' again, just to see if the Fuel Pump will keep Pumping Fuel

You would of course have to be Careful as if the Pump is Working Properly, then Fuel will come hammering out of that Pipe at Full Bore

It Could be a Failing Fuel Pump or maybe a Blocked Fuel Filter but if you can see the Fuel Pump is Continuously Pumping Fuel, then the next Number 1 Suspect could be the Fuel Pressure Regulator on 'B' Bank as these don't last for ever and if the diaphragm is on the way out

Then it won't maintain the Fuel Pressure required to run the Engine

Don't worry about the other one on 'A' Bank as it really isn't needed in the Set Up and even if the diaphragm is broken on this one on 'A' Bank only then it won't make any difference, so don't bother buying a New One for the 'A' Bank Side

It would also be very handy if you were able to Check the Fuel Pressure at the rear of this 'B' Bank FPR

But before you do any of that, could you borrow a Vacuum Gauge to see if the diaphragm on the 'B' Bank Fuel Pressure Regulator can hold Vacuum as you don't really want to buy a New FPR if you don't need one, even though they are not mega expensive $50 ish

The reason that I'm thinking its Fuel, is if She runs on Lighter Fluid, even for a Few Seconds then the Spark to Start Her must be there and should improve once the Engine is running

Moving on from that Scenario, if none of that works, then it could be Blocked Injectors, where my own Car had Six Injectors out of the 12 that were Blocked and I was having the same problem getting her running

Where I had a Spark and She would run on a couple of Tea Spoons of Petrol for just a few seconds but no more than that

Injectors out and I cleaned them which was very easy to do, put them back turned the Key and She's been running Perfect ever since and quite possibly your problem if your Car has been standing for sometime

'The Wizard of Oz' and 'The Alchemist Greg' both told me it was Injectors and Guess What they were Right!

Very easy to take them out and Clean them for just a few dollars

Cleaning The Injectors On An XJS V12

 

Thanks again for the thoughts.

• I had already replaced the FPR on the B side so that should be OK.
• New fuel filter already
• I pulled one of the coils to check it and I had readings of .7-.8 ohms and 4.9Kohms but I can't find a spec?
• So here is my plan:

1. Test that the injectors are actually spraying fuel, and not just clicking. (Note, I had rebuitd the injectors down to the screens and tested them but I'll double check.)
2. Undo the Fuel Pipe from the Fuel Pressure Regulator on 'B' Bank and can slip a hose over that Pipe and try that 'Orange Wire Trick' again, just to see if the Fuel Pump will keep Pumping Fuel.It Could be a Failing Fuel Pump.
3. It would also be very handy if you were able to Check the Fuel Pressure at the rear (outlet) of this 'B' Bank FPR
4. "If she runs on Lighter Fluid, even for a Few Seconds then the Spark to Start Her must be there"

Thanks,Mike ... pls stay tuned

 

Hi Mike

That Sounds Good to me but if the 'Orange Wire Trick' works with a 'Slip on Pipe' hanging over the Wing/Fender, then First try the 'el-cheapo Option' and try a New Fuel Pump Relay or ask a 'Shop' if they would lend you one to try it out

These as I'm sure you know are in the Boot/Trunk behind a Plastic Cover near the Gas Strut that holds the Boot/Trunk Lid open (drivers side on a UK Car)

There are Two Relays and the Fuel Pump Relay sits in the Black Holder and the Main Relay sits in the Red Holder with a 'Red Stripe' these are Not interchangeable, so don't try swapping one for another

But 'Both Relays' have to be Working for the Fuel Pump Relay to Work, so bear that in mind

The 'Nuclear Option' could turn out to be a Faulty ECU but these are pretty hardy and are not known for going wrong on a regular basis and so as these are megabucks that could be getting near to the one for 'The Last Throw Of The Dice'

Injector Problem does seem far more likely and you can take the Front one out (nearest to the Rad) without removing the Fuel Rail or disturbing its Tube, to see if it will squirt into a Jar But (Pull the King Lead out of the 'Dizzy' First) or you could have a Big Fire on your Hands!

So how come 'The Wizard' hasn't jumped into the mix to sort out your problem?

Just take that as being 'Good News' that we 'mere mortals' are on the right lines, as 'The Wizard' will usually only appear 'When All Hope Is Lost' unless he feels like keeping his hand in 'for fun'

We really can't be all that far off now

Good Luck

Alex

 

Mike, your point 3:
No point in testing fuel pressure after the B bank regulator, there will not be any! It is just free flow back to the tank.

 

Hi Greg and Mike

Quick edit: I meant to say Test the Fuel Pressure before the FPR on 'B' Bank but now no need to do that as you now have a New FPR on 'B' Bank, so that one won't be leaking

 

I have tested the injectors in several modes.

1. While Priming- a little spit
2. While attempting a start - a little spit
3. Bench Test - works fine

 

Hi Mike

Looks like Low Fuel Pressure

Could be a Blocked Fuel Filter rather than the Fuel Pump, although if you have Changed the Fuel Filter, it is very easy to put this on the Wrong Way Round and in the event that you may have done this, then it could give you the 'No Start Result' that you are getting now

In any event the First thing to do is to put on a New Fuel Filter which are only about $10-$15 and is never a waste of money or time

If you put on a New Fuel Filter, you would need to Clamp the Fuel Pipe with something like a Protected Pair of Locking Pliers, as the Fuel Pump and Filter are Gravity Fed from the Fuel Tank

Also drain and clean out the 'Swirl Pot' which is located underneath the Battery, where the drain Tap for this is underneath the Car behind a Rubber Blanking Grommet, which just needs a Socket to turn on the Tap and then you can also push on a piece of Plastic Tube to drain the Petrol into a Container

It would also be a good idea to Completely drain the Fuel Tank

Then You can clean out the Swirl Pot and also undo the Locking Ring on the Top of the Swirl Pot, by Tapping the Ring with a Hammer and a Small Wooden Drift to avoid any Sparks

After you've cleaned out the Swirl Pot, underneath the Lid of the Swirl Pot is another Filter, which will also need to be either cleaned or replaced

If that doesn't work, then we can try something else

Good Luck

Alex

 

Fuel pump if after clean out no joy? have you checked to see if fuel is roaring out of the supply line to A bank, as OB suggested?

 

I cleaned out the entire fuel system before I tried to start it.
The only thing I didn't replace was the pump so I ordered one.

I did the flow rate test and not knowing exactly what gushing meant the current pump put out 1.2 liter in .383 minutes (3.13 L/ min or 187 L/ hour) I found a Bosch High Rate pump that claimed 130 L/ hour.

I measured the direct output pressure from the pump and it peaked about 120 psi and then moved down to about 85psi after about 3 minutes.

 

The pump seems Ok then.

 

Hi Mike

Fuel wise that is exactly what you want to see

So We know you've got fuel as well as a Spark, so Theoretically She ought to Start

While I'm going through the list of other possibilities

(1) Have you Checked the Fuel Pump Cut-Out by the Door Pillar? this is a little Plastic Box with a Plunger (Type) Switch inside that needs to be in the down position which you can push down with a Pencil through the little Hole in the Top of the Plastic Box

(2) Is your Car fitted with an immobiliser and if so does the dongle to deactivate it work

(3) Is the Coolant Temperature Sensor Connected

(4) Is the Vacuum Tube Connected to the ECU so it knows what part of the Fuel Map is operating

 

Assuming (perhaps incorrectly?) that the injectors are being triggered by the ECU.....

If you have 80-120 psi raw fuel pressure but are only getting a 'spit' from the injectors I'd be suspecting a problem with the inlet fuel pressure regulator (A-bank, RH side)

Cheers
DD

 

Hi Doug

Genius!

That could be the Answer!

 

Hi Mike

As per Dougs suggestion:

Could you Check the Fuel Pressure coming out of the 'A' Bank Fuel Pressure Regulator

 

Hi Mike

Something else that I've just thought of:

In the Middle of the 'Dizzy Cap' there are Two Posts for the Leads: A Tall Post and a Short Post

On a Genuine Marelli Cap these Two Posts are Clearly Marked 'A' and 'B' but not always so on the Aftermarket ones, even though they may say Made in Italy

In the event that they may not be marked:

The Tall Post goes to 'A' Bank and the Short Post goes to 'B' Bank (easy to get mixed up if you've had all the Leads out of the 'Dizzy Cap') so might be worth checking

Alex

 

Happy Fathers Day ......….Will do checks starting Monday.

What are where is an Immobiliser?

 

Hi Mike

Not all Cars have got an Immobiliser but you would know if you had one, as there would be a 'Dongle' on the Key Ring which you would need to hold close to the Ignition Switch to disarm it in order to Start the Car

There would also most probably be a Reg Light near the Steering Binnacle that would be ON until you disarm it with the 'Dongle' and your Car could also have 'Clifford' etched into the Side window Glass

It might also mention it in the Handbook

 

Todays update.

1. Have you Checked the Fuel Pump Cut-Out by the Door Pillar? this is a little Plastic Box with a Plunger (Type) Switch inside that needs to be in the down position. -- Yup, it was down so I pulled it up and pushed it down to "reset it"
2. Is your Car fitted with an immobilizer and if so does the dongle to deactivate it work. -- No Immobilizer that I can see and no dongle.
3. Is the Coolant Temperature Sensor Connected. -- Yup
4. Is the Vacuum Tube Connected to the ECU so it knows what part of the Fuel Map is operating -- This turned out to be an interesting query.
   1. There appear to be three (3) vacuum hose going from the engine bay through the fire wall. The Yellower one was bit off so I don't know where it goes in the engine bay.
   2. The red one looks like it should be attached to the ECU under the dash, it wasn't so I attached it. It didn't seem to help start the car.
      
   3. There are two hoses under the dash that are not connected to anything inside... where do they go? If one of them goes to the ECU in the trunk, how does it get there?
5. There is a vac line attached to the ECU in the trunk . It has a red strip vs the white / yellowish ones up front. How is the vacuum line routed to the trunk.
6. Since none of them are connected, I'm optimistic this may be the issue.
7. I tested the gas pressure between and it went to 38psi and then the click and it started dropping.

Please advise proper connections for vacuum hoses.
Thanks
Mike