Hayk

iTrader: (1)

I'm suspecting a leak in my fuel injectors, because of a strong fuel smell on cold starts. I would like to test all the lines from the tank up to the fuel injectors to pinpoint the problem.

I bought a fuel pressure test kit, but it only comes with adapters that let you connect in-line with the system. Is this the only safe way to test fuel pressure?


I want to hook up the gauge in the same way as you would if you were measuring tire pressure. Then I would activate the pump and pressurize the line. I was thinking of hooking up the gauge at the fuel tank outlet to see if the pump can hold pressure. Then connect it after the fuel filter to see if the lines from the tank to the engine bay are okay. And finally if I don't get any pressure drops there, I would be able to easily conclude that the fuel rail is the cause of my problems.

Does that sound like a good plan? Would my methods cause any damage?

LeX2K

I don't think you will do any damage using the method you are thinking of. But the leak is probably coming from the fuel pressure regulator.

Hayk

iTrader: (1)

I've replaced almost everything inside the tank - fuel pump, fuel pump sock, fuel pressure regulator, and its filter. I still want to know if I did it right, or if there is something causing a leak.

mdbrown

Aside from the gas smell are there any other symptoms?

dewso1

I get a little petrol smell too, i thought it was normal, so im pretty curious now.

LeX2K

You are talking about the one on the fuel rail, correct? I think Lexus calls this a fuel pulse damper or something like that. To me your thinking is sound, let the pump pressurize the system and isolate.

Hayk

iTrader: (1)

Yes, there are other symptoms. The car takes a few seconds to fire up "cold" and it sounds a bit lethargic if you restart it "hot". When it's hot, upon restarting the engine, the revs don't go up as high as on a cold start. I think the lower revs is normal, but the sound the car makes is just not right.

I've had this issue since I got the car. I went to a mechanic for a fuel pressure test and he said it was a check valve. I took his word for it and started throwing parts at the car - bad idea. After about $400, it didn't get much better. I've cleaned the MAF and my IACV along with the TB, so it's not that either.

I'm currently testing the fuel tank, it seems to be holding well. I'll give it another 20 minutes.

I was talking about about the fuel pressure regulator inside the fuel tank, it's part of the pump assembly.

Are you suggesting that the fuel rail regulator might be faulty?

LeX2K

Yes, they do fail and when they do, they leak, especially when the engine is cold. Not sure it would explain your other symptoms though. It's a tricky part to troubleshoot because it tends to only leak at first, plus the engine gets warm and any fuel evaporates quickly.

LeX2K

They leak onto the engine, at least the bad one I saw did. Well really I never saw the fuel actually leak, but I smelled it. Seeing you have a pressure gauge you will find the leak if there is one.

Hayk

iTrader: (1)

Do they leak onto the engine or is it an internal leak? I don't see anything around it.

After 30 minutes, I lost 10psi at the tank. It went from
44 to 34.

GS4_Fiend

iTrader: (22)

To determine if you got leaky fuel injectors, you would check it during closed loop. Open loop simply means computer is not in control yet and is operated on a certain map that the manufacter had designed for the car. What are your fuel trims reading during normal operating temperature? You would need a scanner that can read live data. Tell me on bank 1 and 2 STFT and LTFT readings are.

LeX2K

According to the service manual:


Start the engine.
Measure the fuel pressure at idle.
Fuel pressure: 301 – 347 kPa (3.1 – 3.5 kgf/cm2, 44 – 50 psi)
Stop the engine.
Check that the fuel pressure remains as specified for 5 minutes after the engine has stopped.
Fuel pressure: 147 kPa (1.5 kgf/cm2, 21 psi) or more

Hayk

iTrader: (1)

I read that too, but it sounds like the bare minimum. What if you have a small leak that takes a few hours to release all the pressure? It would be undetected by the FSM procedure.

GS4, I have a live OBD2 scanner, I just don't have a laptop to hook it up. I'll try to get those readings some time this week.

edit: I removed the fuel pump assembly from the tank, while it was still under pressure. I didn't see or hear any leaks, so I'm thinking that everything is good back there. I did the pressure test a couple of times and it seemed to drop from 44-42 down to about 36-34 consistently. The longest I waited was one hour and it was at 36 when I came back.

I'm now testing the pressure after the fuel filter (inside the engine bay).

INNOUTFAN

Very common problem on many vehicles - GM, Chrysler. Have changed several of these out on GM cars and with those you have to pull the injectors out of the fuel rail. Not sure on the Lexus. Not comparing GM or Chrysler, there is no comparison, just experience with fuel regulators/dampers.

Power6

Hmm the symptoms sound like a leaky injector to me, if the check valve or regulator was leaking, the fuel would be leaking outside the system, or simply back into the tank. The only symptom there should be long startup, or even no symptoms at all, since the fuel pump would prime anyways in a return style fuel system, depends how fast you turn the key. An outside leak should be pretty obvious to the nose.

Fuel trim won't tell you anything, the injectors are only closed for 2 revs of the motor, not enough time to leak anything, leaky injectors manifest themselves when the car is off...