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Mystery Fuel Leak On Injector Stem 'or is it a leaking fuel pressure regulator?'

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XJS ( X27 ) 1975 - 1996 3.6 4.0 5.3 6.0

Mystery Fuel Leak On Injector Stem 'or is it a leaking fuel pressure regulator?'

  #1  
Old 06-11-2018, 04:05 AM
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Default Mystery Fuel Leak On Injector Stem 'or is it a leaking fuel pressure regulator?'

Hi Guys

Please take a look at this Photo



Is this an Injector leak or something else?


Last week when out 'Tripping' all day long I noticed a very 'Sweet Sickly Smell' which I put down to Farmers spraying their fields

But when we got back to base I opened the Bonnet/Hood and saw that this Injector was covered in a sort of 'Sticky Brown Goo'

It looked like Fuel had been 'Cooking' which could have caught fire!

At first I thought the Injector Seal into the Inlet Manifold might be leaking but the Injector Clamp was done up tight

But what is such a 'Mystery' here is that the 'Top of this Clamp' is also covered in 'Sticky Brown Goo' as is the Injector Stem all the way down to the Inlet Manifold

So what on Earth is causing that?

Even more 'Mysterious' is this (see Pic below)



'Sticky Brown Goo' on the 'Thermal Hot Start Switch'


As you can see there is also 'Sticky Brown Goo' on the 'Thermal Hot Start Switch'


This Switch doesn't actually go into the Fuel Rail its blanked off but when the Fuel in the Rail reaches a Certain Temperature the 'Thermal Hot Start Switch' closes


Which then cuts off the Vacuum to the FPR Fuel Pressure Regulator, which in turn then increases the Fuel Pressure to assist with a 'Hot Start' by 'Fuel Enrichment'


There are Two Vacuum Pipes to this 'Fuel Enrichment Switch' and they are not leaking


One goes from the Inlet Manifold to the Switch and the other one goes from the Switch to the FPR (Fuel Pressure Regulator)


(Just a reminder this Switch is also covered in 'Sticky Brown Goo')


As I don't have a Vacuum Gauge, I can't test the Vacuum and I don't have a Fuel Pressure Gauge either


So I'm going to have to take a guess at 3 Possibilities



(1) The Injector Could be leaking


(2) The Fuel Enrichment Switch may be blocked, which would cut off the Vacuum to the FPR and make the Engine run 'Rich' (all the time)


(3) A leaking diaphragm in the FPR (Fuel Pressure Regulator) where the Vacuum from the Inlet Manifold might be sucking 'Raw Petrol' into the 'Fuel Enrichment Switch'


Which then dribbles down on to the Top of the Injector Clamp and then down the Stem of the Injector where this 'Raw Fuel' gets 'Cooked'


Or it could be something else?


Don't really want to have to shell out megabucks for a New FPR if that's not the problem


I've done an extensive write up with more Photos from different angles on Page:87 of my 'Cherry Blossom' restoration thread


Here is a Link to that page: https://www.jaguarforums.com/forum/x...122634/page87/
 
  #2  
Old 06-11-2018, 05:01 PM
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Which cylinder is the suspect injector on?

What does the goo feel like, does it feel like oil?

Does it smell like oil, or like gasoline?

Thanks,

John
1987 XJ-S V12
 
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  #3  
Old 06-11-2018, 06:19 PM
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Originally Posted by J_C_R View Post
Which cylinder is the suspect injector on?

What does the goo feel like, does it feel like oil?

Does it smell like oil, or like gasoline?

Thanks,

John
1987 XJ-S V12
Hi John

The Injector is on 'B' Bank right underneath the Cold Start Enrichment Switch

When we went out Tripping last week I noticed a very strange Sweet Sickly Smell and when we got home I looked under the Bonnet/Hood

And saw the Stem of this Injector and the Top of the Injector Clamp covered in this Goo, which I thought might be from the Ethylene in the Petrol being 'Cooked' on the Inlet Manifold

But it was definitely Sticky 'Like Varnish' and quite hard to get off, so I had to use some Turps on a bit of rag

Having cleaned the Goo off, by the time I put her in the Garage (only a couple of hundred yards away) the Goo had started to come back

What was strange was that the Goo was on top of the Clamp, as you can see in that photo

So I thought it might be a Petrol Leak from the FPR to the Enrichment Switch which was then dripping down on the Injector

But Today I checked the Enrichment Switch (The Hot Start Switch) and it was as clean as a whistle and so were the Vacuum Tubes, so it wasn't that

Then I took the Clamp off 'The Suspect Injector' and saw that Goo seemed to be leaking out of the Top of it and running down

Which could explain why the Top of the Clamp was getting covered in Goo

So I am thinking that the Top of this Injector is leaking, which I have never heard of happening before (Is that actually Possible?) or am I imagineering?

If that is in fact possible, then it would seem that this Injector needs changing

Or could it even be something worse than that?

You can see more Photos of this on Page 87 of my 'Cherry Blossom' restoration thread and here is the Link to that Page: https://www.jaguarforums.com/forum/x...122634/page87/

I hope it is just the Injector, what do you think it might be?

Very Strange not heard of this before but maybe 'The Wizard' has seen this on his Travels
 
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Old 06-11-2018, 07:40 PM
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I don't think that you have a cold start enrichment switch on a 90. I also have a 90. The switch in your photo reads temp on the fuel rail, if I understand the system correctly. It screws up against the fuel rail. Eliminate a leak by disconnecting the two wires and unscrew the switch just to make sure that there is not a leak in the square rail inside that threaded boss for the switch.

How long have the injectors been installed? If you have been driving the car for a while, I would be surprised if it has just started leaking.

Feel the hose at the top of the injector at the fuel rail. Wet or dry? By 90 there were no injector hose clamps, just the barbs that the hose slides onto. Is this the only injector that has the residue? Did you change hoses on the injectors during your restoration?

There is a "Y" shaped steel pipe connecting to both intake manifolds that also has the PCV valve and slides into the left side air cleaner box. Look at the left air filter and inside the box. Are you seeing engine oil? The pipe is also connected to the crankcase vent. What I am leading up to is where is the steel "Y" shaped pipe positioned in regard to this injector? Examine the underside of the line with a mirror and light.

The residue looks more like engine oil to me that evaporated gasoline. I think that you may be sucking oil through the steel "Y" line and it is dripping at the rubber hose that connects the line to the left bank intake manifold.
 
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  #5  
Old 06-12-2018, 02:46 AM
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Hi Mike

Yes it is a Temperature Switch that goes into a Blanked off part of the Fuel Rail but I just call it a Fuel Enrichment Switch (for hot starting)

This is the only Injector that has residue and you are right again!

This residue does look a lot more like Oil than Petrol

Which would probably have evaporated on Contact (or caught Fire) and one end of that 'Y' Pipe (with the rubber joiner) is right over the Top of this Injector

So as you say that Pipe could be Sucking Oil from the Crank Case Vent

Is this a Major Problem or a Minor one?

What is the best thing to do?

What would cause this to happen? is there a Major Problem somewhere or is this not that unusual?

Still a bit early in the UK but I will check the Air Cleaners and that pipe ASAP

I think you may have nailed it but I just don't know how to fix it, as its never happened before

Thanks for your help
 
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Old 06-12-2018, 04:27 PM
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Update:

The 'Y' Pipe doesn't appear to be the problem as it is nowhere near the Injector that appears to be leaking Oil or Petrol or Both (on 'B' Bank under the Thermal Switch)



The 'Y' Pipe isn't leaking and is nowhere near the Injector which is just underneath that fitting where the Thermal Switch Screws in


The Fuel Pipe from the Fuel Rail to the Top of the Injector does not appear to be leaking, it is dry and so is the Fuel Rail

When I took the Cover off the Air Cleaner, there was a small amount of Oil in there but did not seem enough to worry about (or am I wrong? see Photo)



A small amount of Oil in the Air Cleaner but the Actual Filter was dry and not covered in Oil




A Small amount of Oil in the Bottom of the Air Cleaner but didn't seem enough to worry about or am I wrong?


Conclusion:

Somehow and someway, a Gooey Oil Substance is finding its way to the Top of the Injector Rim and the Injector Clamp and Stem of the Injector

It 'Seems' to be Starting on the Rim on the Top of the Injector and then working its way down

Have a look at this Close up Photo of the Rim of this Injector



The Oily substance seems to start at the Top of the Rim of the Injector




Oily Substance seems to form on the Top Rim of the Injector Note how the Fuel Pipe is showing no signs of leaking


Could the Injector be leaking from the Top Rim? (unusual but could be possible?)



Where the heck is this Oily Substance coming from? Note how the Fuel Pipe is Clean and not leaking




When I cleaned the Oil Off it came back in a very Short Time


Does this sound like a Plan?

Clean the Oily Substance Off and then Run the Engine to see if I can see the Goo coming back

I was planning to do this today but its been raining all day, so maybe tomorrow

It could be a Faulty Injector but I'm having a real problem finding the cause and to make matters worse the MOT is due next week
 

Last edited by orangeblossom; 06-12-2018 at 04:29 PM.
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Old 06-12-2018, 07:08 PM
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Im thinking the injector is bubbling out it’s coil’s coating. Is it overheating? If you have a digital thermometer read 4-5 injectors temps and compare to this ones.

Digital thermometers aren’t super temperature accurate and laser-scalpel accurate in sample area. Just be consistent in your samples. The actual temps don’t matter, just their relative consistency.
 
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Old 06-12-2018, 08:19 PM
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OB;

I noticed in your photo that you have only one clamp on the hose, at the Y tube and not at the manifold. Add a second.

Over by the radiator expansion tank There is a vacuum valve that I have had trouble with the hose filling with oil that then gets sucked into the Y tube. The valve feeds into the carbon canister. We have enough miles on our cars (107,000 on mine) that these systems start to act up.


Check the PCV valve. The check valve should be loose. You may have sludge in it making it stick. Second remove the rubber boot or the crankcase vent. There is a round metal tube about 2" long and about 1 1/4" in diameter. Soak it in carb cleaner and after it appears clean, reinstall it.

See if those two things help.
 
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Old 06-12-2018, 08:29 PM
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Looking closer, I agree that then Y pipe may not be the cause. I still think you should clean the goo start the car in park and examine the injector with a light and mirror.

Just another weird thought. Do you have a black light? The air conditioning compressor is not far from that location. Run the air to see if you lost Freon and perhaps compressor oil. If it is refrigerant oil, it will have dye that fluoresces.

It has to be coming from somewhere.
 
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Old 06-13-2018, 12:04 AM
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Originally Posted by JigJag View Post
Im thinking the injector is bubbling out itís coilís coating. Is it overheating? If you have a digital thermometer read 4-5 injectors temps and compare to this ones.

Digital thermometers arenít super temperature accurate and laser-scalpel accurate in sample area. Just be consistent in your samples. The actual temps donít matter, just their relative consistency.
Hi Jig Jag

Not being a proper Mechanic, I am not quite sure what you mean by 'coil's coating'
do you mean the rim around the Top of the Injector?

I've got a Lazer Thermometer so I will do that Test as well

With the benefit of hindsight, when I cleaned the Injector off I should have re-started her and then watched to see what happened

But the whole thing looked so bad it kind of threw me and I was starting to think about Valves and other assorted XJS nightmares!
 
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Old 06-13-2018, 12:08 AM
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Originally Posted by mikebaker3 View Post
Looking closer, I agree that then Y pipe may not be the cause. I still think you should clean the goo start the car in park and examine the injector with a light and mirror.

Just another weird thought. Do you have a black light? The air conditioning compressor is not far from that location. Run the air to see if you lost Freon and perhaps compressor oil. If it is refrigerant oil, it will have dye that fluoresces.

It has to be coming from somewhere.
Hi Mike

Unfortunately I don't have a black light
 
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Old 06-13-2018, 12:13 AM
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Originally Posted by mikebaker3 View Post
OB;

I noticed in your photo that you have only one clamp on the hose, at the Y tube and not at the manifold. Add a second.

Over by the radiator expansion tank There is a vacuum valve that I have had trouble with the hose filling with oil that then gets sucked into the Y tube. The valve feeds into the carbon canister. We have enough miles on our cars (107,000 on mine) that these systems start to act up.


Check the PCV valve. The check valve should be loose. You may have sludge in it making it stick. Second remove the rubber boot or the crankcase vent. There is a round metal tube about 2" long and about 1 1/4" in diameter. Soak it in carb cleaner and after it appears clean, reinstall it.


See if those two things help.
Hi Mike

Where do I find the PCV valve and the Crankcase vent, as I've got no idea what these things look like or where to find them

Would you happen to have a Photo to pinpoint their location
 
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Old 06-13-2018, 07:45 AM
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Originally Posted by orangeblossom View Post
Hi Jig Jag

Not being a proper Mechanic, I am not quite sure what you mean by 'coil's coating'
do you mean the rim around the Top of the Injector?
Anything electrical that moves has a coil of wire somewhere that creates a magnetic field when you pass voltage through it. This attracts a magnet and creates movement. In this his case it pushes the pintle seal open.

If things go all Lucasy the coil can short which absorbs the same voltage using less wire. It can heat up far beyond its design specs. Whatever insulation coats the wire, or epoxy that surrounds the coil can be hated to liquid or vaporized.

If you have something that looks like itís oozing out of the injector then itís a possibility. Ohm the injectors to test would have been better advice than suggesting the laser.


Originally Posted by orangeblossom View Post
But the whole thing looked so bad it kind of threw me and I was starting to think about Valves and other assorted XJS nightmares!
i know that feeling.
 
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Old 06-13-2018, 07:52 AM
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Hi Guys

I think I may have found the source of the Mystery Sticky Goo on the Injector!

But don't know how to fix it

At first I thought the 'Rogue Injector' might be leaking Petrol round the Rim at the Top and then trickling down the Stem where it was 'Cooking' on the Inlet Manifold

Where it was producing a very Sweet Sickly Smell



Where was this Goo coming from?




Where was this Goo coming from? I thought it might have been a leak from the Injector Hose except the Injector Hose was Clean and Dry


The Injector Tube was Clean and Dry and the Clamp was done up as tight as it should have been, as in 'Tight but Not Stupid Tight' @ 'The Wizard of OZ 'Grant Francis'

Maybe the Injector Seal was leaking? As this 'Goo' was Pooling around it and certainly looking like suspect No1

But what was even Stranger was that there was this 'Sticky Goo' around the 'Thermal Hot Start Switch'

At which point it may be worth mentioning that this Thermal Switch is screwed into the Fuel Rail but it is Blanked off and doesn't come into contact with the Fuel

So Fuel directly leaking out of the Rail at that point is almost impossible to imagine happening

It was suggested and could have been Oil being sucked into the Inlet Manifold from the 'Y' Pipe and while I am not ruling that out completely.......

Today I decided to give that Injector a really good Clean and then Start her up and watch what happens (couldn't do that Yesterday it was raining but I checked all the Tubes for Oil)

Having got her out of the Garage, I started her up and then I watched what happened while keeping a very close eye on the 'Suspect Injector'

Where I got her right up to Normal Running Temperature

'Shock Horror!' No Signs of any Petrol Leaks or Goo!

Until I switched her OFF!

At which point a Petrol/Oily Substance was starting to form around the 'Thermal Switch'

This was where the Rubber Tube from the FPR (Fuel Pressure Regulator) goes on to the Thermal Switch, as does the Rubber Tube from the Thermal Switch to the Inlet Manifold

This was enough to Wet the Tip of my finger and also had that very 'Sweet Sickly Smell'



An Oily Petrol like Substance was leaking from here, where these Rubber Tubes join onto the Thermal Switch for (Hot Starting) and had that same 'Sweet Sickly Smell' that I had noticed when we were out 'Tripping'




If you look very carefully you can see this 'Goo' is starting to Pool at the Point where the Bracket joins on to the Fuel Pipe


It wouldn't have taken very long for that 'Goo' to drip off the Bracket onto the Injector Clamp and then onto the Rim of the Injector

Which could give the impression that the Injector was leaking, although that now does not look like the problem

Somehow Oil/Petrol = 'Goo' is getting to that Thermal Switch and dripping down onto the Top of that Injector

Since one of those Vacuum Pipes comes off the FPR (Fuel Pressure Regulator) I'm wondering if the diaphragm in the FPR may be leaking?

Any ideas?
 
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Old 06-13-2018, 10:17 AM
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Seems to me that somewhere in your posts that you purchased a hand vacuum pump. Try pulling vacuum on the fuel pressure regulator and see if it hold or leaks off. If it leaks off you have a bad diaphram.
 
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Old 06-13-2018, 11:37 AM
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Originally Posted by catterwaller View Post
Seems to me that somewhere in your posts that you purchased a hand vacuum pump. Try pulling vacuum on the fuel pressure regulator and see if it hold or leaks off. If it leaks off you have a bad diaphram.
Hi catterwaller

Unfortunately not (Lol)

I picked up an Amp Meter and some other 'Gizmo' that I can't remember the name of but very sadly not a Vacuum Gauge

Which of course I could really do with now!

But when I pulled the Vacuum Pipe off the end of the FPR it was quite Wet with something that resembled Petrol and sort of smelt like Petrol

More like Waxy Petrol than just Goo, so I'm thinking the FPR could be a bit suspect, so it might be worth a Roll of the Dice to go and get another one

As it seems pretty much Certain that it isn't the Injector after all
 
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Old 06-13-2018, 11:44 AM
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Hi Jig Jag

Thanks for your help as always but it doesn't now look as if it is the Injector but after Consulting the 'WOZ' we may be getting closer to solving this problem
 
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Old 06-13-2018, 04:54 PM
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Another 'Wizard Fix!'

'The Wizard of Oz' knew what it was and Fixed it!

Full write up on Chapter 87 of my 'Cherry Blossom' restoration thread

Here is a Link to that Page: https://www.jaguarforums.com/forum/x...7/#post1912629
 

Last edited by orangeblossom; 06-13-2018 at 06:00 PM.
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