How to locate faulty fuel injector and how to replace.

[Mgrene]

Evening Forum.

 

On the way home from vacation my Supra lost fuel pressure.

 

I have done some reading on the internet and based on the symptoms I am 90% certain that one of the fuel injectors are broke (gasoline smell around and inside the car).

I know there are several tests that can be done but after watching you tube for 30 minutes I do have a few extra questions.

 

Hopefully it is only one injector that is broke/leaking. I have read there is the possibility that it is an internal or exxternal leak. How do I check if it is an external leak?

 

I have absolutely zero experience with replacing injectors but I prefer to do the replacement myself. Is it just a question of disassembling the injector from the fuel rail or is it more complicated than that?

 

 

I have searched the forum for a guide but without luck?

 

The car is being towed back to Denmark from Austria in 10 days so I cannot start working on it before that.

[Shane]

What makes you think it's one of the injectors? You can link 2 of the connectors in the diagnostic port to make the fuel pump run continuously, its FP and one other B+ maybe, sure someone else can confirm what the other pin is, but anyhow if you do this and force the pump to run you should then see where the fuel is leaking from. I've owned and worked on a few now and apart from one that someone had taken the fuel rail off and then put it on with a spacer missing, I have never known the injectors to leak.

 

TT or NA?

 

Has it got an after market FPR fitted or is it OEM?

 

I would start with getting it pressured and looking for the leak.

 

Edit: Yes, linking B+ and Fp connection found in the diagnostic port will run the pump

Edited July 19, 2016 by Shane (see edit history)

[Mgrene]

What makes you think it's one of the injectors? You can link 2 of the connectors in the diagnostic port to make the fuel pump run continuously, its FP and one other B+ maybe, sure someone else can confirm what the other pin is, but anyhow if you do this and force the pump to run you should then see where the fuel is leaking from. I've owned and worked on a few now and apart from one that someone had taken the fuel rail off and then put it on with a spacer missing, I have never known the injectors to leak.

 

TT or NA?

 

Has it got an after market FPR fitted or is it OEM?

 

I would start with getting it pressured and looking for the leak.

 

Edit: Yes, linking B+ and Fp connection found in the diagnostic port will run the pump

 

Hi Shane.

 

I have done some reading on the internet concerning symptoms when experiencing loss of fuel pressure and together with that, and from my own "logical view" I find it difficult to believe that the issue is located somewhere else than the injectors. I am not saying that I am right but let me specify.

 

Normally my fuel pressure is 3 bar when engine is running. When I turn off the car, the pressure drops a little bit (not much, maybe to around 2.7 bar).

Recently I have noticed that the pressure drops down to maybe 1.5 bar or so when I turn off the car. First warning sign that I saw some months ago but I chose not to take any further notice.

When the pressure started to drop when the engine was running, this only happened gradually not instantly.

 

All the fuel lines are having a "free play" under the car which mean that if they are leaking I should definitely be able to see gasoline spots on the floor under the car. But no sign of that.

Furthermore, if there is a leak somewhere, I believe that the pressure should drop immediately to 0 bar when car is shut off. But it doesn't.

 

There is also a smell inside the car of gasoline when the car is running (smells like it comes from the vents but not 100% sure). As mentioned, the fuel lines are running under the car and if they are leaking I do not believe that the smell will move from under the car into the cabin.

 

Then we are back to if there is a loose connection inside the gas tank, but again I do not believe that it will cause a smell inside the car.

 

Therefore I believe that the leak is somewhere in the engine room and if you read on the internet, a leaking injector may cause smell of gasoline in the cabin and around the car. I am not talking about an internal leak inside the injector (because then it should run very rich but it doesn't according to my AFR. It shows very lean when I open up for the throttle) but a leak between the injector and engine and/or fuel rail. But the leak is so small that I cannot spot it while engine is running, which I also think is the reason why the bar pressure only slowly drops when engine is shut off.

 

I may be way of and when I get the car back it makes sense to start from the very beginning at the pumps and then just check all connections up to the engine room.

 

Btw: Fuel pumps are running (I can hear that when I turn on the ignition).

 

My setup is 2 x walbro, HKS twin feed fuel rail, HKS 1000cc injectors.

 

Edit: Its a TT-T and I believe FPR is Fuel Pressure Regulator. If so, it's an aftermarket one.

Edited July 19, 2016 by Mgrene (see edit history)

[Chris Wilson]

If an injector leaks it's either external with fuel all over the outside of the engine, or internal and floods a cylinder and probably hydraulically locks it doing a LOT of damage. I would check the lines to and from the tank. The fuel pressure should NOT drop to zero on key off, ideally it should remain at line pressure for a long time. I distrust all but Bosch adjustable aftermarket fuel pressure regulators. The fact there's a fuel smell suggests there MUST be an external leak somewhere. None Teflon lined fuel hose degrades with unleaded fuel and osmosis occurs, followed by a proper leak. Ar the hoses Teflon lined?

[Mgrene]

Thanks Chris.

I guess best thing is to just start from one end (the tank) and then move forward.

By the way, I have read somewhere that you can check if you have a faulty fuel pressure regulator by checking the vacuum hose that goes from the regulator. If gasoline drops when ignition is on, the regulator is leaking.

Is this true?