Hi Sardonicus

In that case it's looking like possibly one of 3 Things

If you have a look at the Fuel Pump Relay in the Black Holder and the Main Relay in the Red Holder, they are not exactly the same as they may look

As the Main Relay has (or should have) a Red Diagonal Stripe which the Fuel Pump Relay doesn't have (or shouldn't have) and while some say that this doesn't make any difference, the Red Stripe on the Main Relay (in the Red Holder) indicates this Relay has a Diode

Which may have got 'Fried' if someone had ever swapped them over, which could be why the one you pulled apart looked a bit Scorched, as I 'think' the diode protects the Relay in a similar way to how a diode can blow on an Alternator

In these no Fuel Situations, 'The Coolant Temperature Sensor' is very often 'Suspect Number One' as if either that or its Wiring Fails then the Signal to the ECU will be all over the place and as such won't be delivering the right amount of Fuel at the right time, or even sometimes maybe no fuel at all, as maybe the case here

Coolant Temperature Sensors are 'as cheap as chips' and so it could be well worth while to fit a New one and also double check the Wiring and Plug

If none of that works then it could be time to go for the 'Nuclear Option' and fit a New FPR (Fuel Pressure Regulator) to 'B' Bank, as if the diaphragm inside has started to go porous, then it may be letting Fuel through, while failing to hold the Fuel Pressure of 30 psi

Unless you can rig up something, so you can check the Fuel Pressure in the Rail

The FPR on 'B' Bank run out at about $50 which could be a bit of a hit, although that is the Cheaper on of the two

The other one being on 'A' Bank which really isn't needed and is not the one that you wan't to replace

So Start with the integrity of the Wires to the 'Coolant Temperature Sensor' and then progress from there

 

The relays were both the same when I started this little adventure, looked to me like generic 5 pin 30 amp bosch relays. I replaced them both with equally generic 5 pin 30 amp relays.

As for the coolant temp sensor, looks like about 30 bucks to replace, so thats not awful. Is there a way that I can test either the sensor or the wiring with a meter or something?

 

The power and fuel pump relays are NOT the same. The fuel pump relay is fairly standard, but the power relay has a diode in it to protect the ECU from hooking the battery up backwards. Always make sure the relay terminal markings are identical because some XJS relays have different 5th terminal functions. Kirby Palm's Book has a in depth discussion of relay differences.

 

Beside with/without the diode pay very careful attention to the terminal designations, yes. The main and pump relays are known as "dual 87" relays. The terminals are 30-85-86-87-87. Most generics are 30-85-86-87-87A which function quite differently !

Cheers
DD

 

Ok so looking at the old ones that were here when i started, they are the same and they are 30-85-86-87-87. The generic ones from the parts store are the 87A. I will look for a proper main relay, or as kirbys book suggest I might just wire in an appropriate diode going to the relay so a special relay is no longer necessary to protect the ecu from people hooking up the battery backwards. Can the 87A relays be used here at all like for the fuel pump or should i be seeking out another relay for both?

 

Gotta have the the dual 87 relays

With the 87A type relay whatever is connected is 87A is DEpowered when the relay is triggered

Cheers
DD

 

When you have the fuel pump relays etc renewed, I suggest you test the injector circuit at the injector as follows, if you have not already done so:

1. get a probe on a meter or a test light
2. peel back the insulating boot from the back of an injector plug on your new loom, so you can get the probe down the wire going into the back of the metal terminals
3. clip the plug back on the injector, switch on ignition
4. you should have 12 v on BOTH wires into the plug

If you do not, you have a loom fault. (this is a Grant Francis diagnosis procedure).

 

Hi Sardonicus

Sounds a bit expensive to me

New Coolant Temperature Sensors on ebay £8 to £10

How to Test a Coolant Temperature Sensor (The Quick and Dirty Way!)

Set your Meter to Ohms (about 200k)

If you have a 3 Prong Sensor then just put your Meter on the Two outside Prongs

Or if a 2 Prong Sensor then one probe from your meter on each one of those Prongs

No Need to take the Temperature Sensor out of the Car! If you get a 2 ohm Reading then your Temperature Sensor is OK

If you don't get a Reading then your Temperature Sensor is not OK

For more extensive Testing, take the Temperature Sensor out of the Car and using the meter as before (Set to 200 ohms)

Put the Probe of the Temperature Sensor into Cold Water and (Take a reading) then into Warm Water and (Take a reading) then into Hot (but not boiling Water) and also (Take a reading) Note: You may have to adjust the ohm Setting on your Meter for Very Hot Water or it can go off the Scale

As the Temperature Rises, the Resistance Drops and that is really all you need to know!

 

So, I put a meter on the coolant temp sensor, which in my case is a 2 prong sensor. The meter auto ranges to k and outputs a reading of 4.00.

 

If the car ran BEFORE you worked on the injector loom and didn't run AFTER your work, then my suggestion would be that the problem is in the repaired loom... no?

 

I hear ya, but I dont see where. Its wired right and all the plugs have voltage.

 

At both pins to the plugs, as per the test outlined in my last post?

 

That's great, but half of it. The other half is the reliable grounding of the FIs... Are the FIs being grounded in time and order but the ECU?

 

Yes. I back probed every one of them and both pins on every plug have 12 volts.

 

It doesn't take a big mistake in the wiring of the fuel injection harness, to have it not work.

12v on both side of each and every connector with the key in the on position,,,,? If so, it's waiting for ground signals to fire the injectors, in groups of 3. Groups of 3!?!?! Or is it 4!? Groups of 3, I think. Anywho,,,

Whenever I am having problems with my v12 I RESIST saying to myself that this and that is verified, correct, right, good and as it should be if it ain't running. The car taught me better

I'd guess something in that harness is amiss.

 

It is groups of 3. With 12 volts at every connector with the key in the on position, what is left that could be wrong in the new harness? Its whole purpose is to get that voltage to the injectors while the system waits on the signals from the ecu, isnt it? I checked and rechecked and then checked again that I had the proper wires from the old plug that I cut off matched up to correct sets of 3 injectors. At this point it would be nice if I could find something wrong in the new harness so at least then I'd have something to fix.

 

Maybe this has already been mentioned but have you checked the dreaded white wire at the amplifier?


Cheers
DD

 

The amplifier wires are disgusting right now, but I haven't messed with them and I have spark. Is there something from the amp that goes to the injectors?

 

I Just found this broken wire. Might be unrelated. Right side of the engine compartment. Looks like it use to be pink and black. It routes up the wall and into the big bundle of wires that I guess goes to the rear? Not sure exactly. And as of writing this post I can't find the other end but I am looking

 

I was doing some reading and came across something about a trigger unit. It sounds like something that connects the ignition system to the fuel system. Is that a thing on my car? And could i have disturbed it pulling the old injector harness?