When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hi guys, pretty confident firing order is correct. Dizzy has cylinders moulded in and all plug leads labelled, pretty straight forward tbh.
Not replaced rear crank sensor, looks a right pig! I'm beginning to think it's fuel related as it chugs and splutters then dies. If I try again immediately it does the same but splutters for less time before dying. Trying again it doesn't fire at all.
If I leave it then try again it splutters for longer and the cycle restarts.
I wonder if I'm getting fuel pressure and sort of using all the fuel up in the system and it's not being replenished quickly enough?
If that's the case why would i have correct fuel pressure at the rail and injectors firing.
If the Fuel Pressure Regulator (FPR) on 'B' Bank has a leaking diaphragm, then it may initially give you the correct fuel pressure before it leaks through the diaphragm and tails off
The FPR on 'B' Bank is the only one to concern yourself with, as the one on 'A' Bank is not needed and was omitted from the Fuel Rail on the later Cars
Another possibility is a Blocked Fuel Filter and also the 'Possibility' that the Fuel Filter has been put in the 'Wrong Way Round' it happens!
Another thing worth Checking out, is the Fuel Pump Relay which could be on the 'blink' this is located in a Plastic Box by the Hinge on the Boot/Trunk Strut
There are 2 relays in there and the Fuel Pump Relay is the one in the Black Holder and the Main Relay is the one in the Red Holder with the Red Stripe (Note these Relays are NOT interchangeable as the one with the Red Stripe has a Diode)
Also Note that Both of those Relays (The Main Relay and The Fuel Pump Relay) need to be working
To Test the Fuel Pump Relay 'Take the Wires off the Fuel Pump' and then Connect a Test Light to those 2 Wires, then get someone to Turn on the Ignition, while you watch the Test Light
The Test Light should light for Only about 3 Seconds and then turn off of its own accord
Repeat this Test half a dozen times just to be sure and if the Test Light doesn't come on or go off after 3 Seconds with every Ignition Key 'Actuation' ie Ignition ON/Ignition OFF
Then One or possibly both of those Relays may need replacing
Fuel Pump Relay Location by the Gas Strut Hinge in the Boot/Trunk
The Fuel Pump Relay is in the 'Black Holder' The Main Relay is in the 'Red Holder' with the 'Red Stripe' Not Interchangeable
Both Relays need to work for the Fuel Pump Relay to Work
I also made a short Video of how to Test The Fuel Pump Relay which you can see on Page:46 of my 'Cherry Blossom' restoration thread and here is a Link to that Video
If you think fuel is the problem, spray starting fluid (ether) into the intakes and see if she starts and runs OK. If she does, it is a fuel problem.
It just could be that the fuel pump is not running once the engine fires and the starter is released, for some reason. Have a helper listen in the boot to hear if the pump stops once the starter is released and the engine is trying to run. If it does, rig up a temporary feed to the pump positive and see if the car starts then.
Also, check the engine earth strap is clean and making full contact engine to chassis frame.
Just thought of another possibility, maybe its one of the Coils as I have heard that a faulty Coil could produce the Symptoms, that you have been talking about
If all else fails, it could be that and I don't think the Aftermarket Coils are too horrendously expensive in the scheme of things have a look at SNG Barratt
Tried hard wiring the pump, it's whizzing away- no difference
New crank sensor at front - no difference
Fuel relays were wrong way round, corrected - no difference
Fuelines into fuel rail after fpr we're plumbed into bottle - lots of fuel coming through
However I did notice when it was cranking and chugging there was no reading on the rev counter. I read somewhere this is fed by the rear crank sensor.
I did unplug it and crank the car and it didn't attempt to fire, when I plug it back in it goes to its chugging self so assumed it was this.
Could this be the issue then?
Thanks again
Simon
Last edited by Skinthespin; 01-19-2019 at 10:38 AM.
If the Tacho doesn't move when you Crank the Engine that could be a sign that the Crank Sensor may need replacing but it could also be that the Plug of the Crank Sensor may be Corroded or dirty
The Crank Sensor is also a bit prone to getting covered in Oil and Crud, so best check that as well
Since you mentioned the Relays were the wrong way round, it is also possible that this may have blown the diode on the Main Relay, that's the one with the Stripe in the Red Holder
Can you get one from a 'Scrapyard' to try out or borrow one from a 'Shop' and see if it makes any difference, although from what you say its looking a lot more like the 'Crank Sensor' at the moment
Checked the plug OB, cleaned with contact cleaner and did a bit of scraping. Also hard wired the fuel pump to the battery so am assuming this would bypass a broken relay?
Is the rear crank sensor as bit a pig to change as it looks? Don't fancy crawling underneath the car to change it.......had to jack the car up to change the front one but your only poking your head a foot under the vehicle, the rear one is right in the middle.
Is the rear crank sensor as bit a pig to change as it looks? Don't fancy crawling underneath the car to change it.......had to jack the car up to change the front one but your only poking your head a foot under the vehicle, the rear one is right in the middle.[/QUOTE]
I did this job early on in the restoration of my convertible. A very good tip was offered to me by either gene in the USA or grant in oz. no matter. Tie some string to the end of the sensor in the engine bay to help you re thread the new one back through. It can be a bit fiddly but very do able if you use the string. You will need to go under the car and probably many more times in the future. That I can’t help you with as it is something I do regularly. Every man is their own safety officer and being safe is paramount. Good luck.
Hard Wiring the Fuel Pump will only Test the Fuel Pump not the Relays
Since you found the Relays were the wrong way round, from that it would seem that someone thought that there was a Relay Problem and swapped them around just to see if that would make any difference
Maybe totally unaware that the Main Relay in the Red Holder with the Stripe (unlike the Fuel Pump Relay) is fitted with a Diode where Swapping those Relays around Could Blow that Diode and in doing so could mess with the Fuel Injection
And so your best plan could well be to get hold of a Main Relay (The one with the Stripe) and see if that makes any difference
Also when you changed the Front Crank Sensor did you check the 'Gap' which could be critical and if I remember correctly can be adjusted by shims
The Gap (from memory) should be 018-1.042 ins or 046-1.07 mm
As for the Rear Crank Sensor, if you need to change it then it would be a lot easier as well as a lot Safer to let a 'Shop' do this for you on their Ramp
Sometimes its so easy to overlook the obvious, though all the same this may be a bit of a long shot 'or maybe not'
Could it possibly be the 'Cats' are blocked?
Which may go someway to explain the bogging down that you seem to be getting, when all the other systems appear to be working with the possible exception of the 'Crankshaft Sensor' and 'Main Relay which up to now are are still an unknown
Having just re-read your thread right from the beginning, I am now starting to wonder if your Car may have had or have been very close to a 'Marelli Fire' which not all 'Shops' may be familiar with
To put that in a 'Nutshell' the 'Rotor' inside the 'Dizzy Cap' develops a short which can shut down one Bank of Cylinders, as the V12 is like 2 X Six Cylinder Engines joined together
At which point, Raw Fuel continues to be pumped into the Exhaust of the Bank of the Engine that has just shut down, which then has the potential to turn a Car into a Fireball
But even if it doesn't quite get to that stage, either one or both of those 'Cats' can glow red hot and get blocked, which in turn could then cause the engine to bog down
I am only briefly touching on this, just in case you are already familiar with this concept although if not then it could be well worth looking into
One of the most common causes, is the failure to change the Spark Plugs underneath the Air Con because they are such a PIA to get to
Have you got a Photo of the Inside of your Original Marelli 'Dizzy Cap' together with the Rotor?
Were there any signs of 'Burning or something shorting out'
Although from what we know so far is, 'Suspect No1' could very likely be a burnt out diode inside the 'Main Relay'
(The one in the Red Holder with the Stripe) as that could really upset the Fuel Injection
Main 'Relay' failure (Burnt out Diode) seems much more likely than the 'Crank Position Sensor' (At the moment)
Can you get hold of another 'Main Relay' to try it? (not very expensive and very easy to change)
Car is with mdm jaguar and he swapped various parts off the car with another one. Turns out the engine loom is faulty. The one that joins ecu to coil packs, amps etc.
I can get one made at work but won't be for a while. I also can't seem to track down an alternative that might be a bit quicker.
What's the exact nature of the fault? Typically the wires get baked and brittle, and the connectors dirty/weak/corroded.
I've always managed to repair the existing wiring. Clip off the bad stuff and solder-in new pieces as needed.
For the fuel injector wiring....which you didn't specifically mention but probably need.... most of us make up a new harness on our own. But you can buy 'em pre-made.
I think this outfit offers (at least some of) the V12 engine wiring
01-12-2019, 05:36 PM
