tombrokeanotherone

well I've fixed mine and returning here to post how! I've tested the resistance on the fuel pressure sensor ( on the fuel rail ) and it was fine and within spec, the problem I had was the pressure discharge valve/ suction control valve - the thing that lives on the back of high pressure pump attached by allen keys- the values that I had for resistance didn't match what I was told is the correct readings, however, even the replacement valve had the same 'incorrect' readings, so maybe that changes based of the part code and pump used. removing the valve can be done easily with engine in, however, the replacement part that I sourced through a local diesel specialist was actually longer than the original, so re installation required undoing the engine mounts from below the car and jacking the engine up and giving it a wiggle to be able to reinstall the new one- fiddly but much easier than removing the whole engine to replace the pump! the reason it's now longer is that the original lexus part and pumps are actually discontinued from denso and to make things complicated, those valves are paired by part code to the fuelpump part codes, so you can't just take a valve out of a breaker car if the pump part code doesn't match. knowing the part codes (black sticker ontop of pump and an etched code on back of sensor) I was able to get a valve for use on the newer revised high pressure pump- even the specialist who sourced this suggested the pump would be required aswell... after a prime for 2 mins it fired straight up, so despite what lexus and specialists will tell you, you do not need to replace the pump at a cost of £1200. you need a £120 part. if you happen to have this problem remember that the pumps and valves must match, so people breaking them sell the whole pump assembly, which given this is a common problem I wouldn't suggest saving money there, especially when you think that it will require the engine to be removed to even get the damn pump off!

the reading was 3.5, which is miles out however, even the new replacement pressure discharge valve which has worked was the same resistance reading as the faulty original that was removed. I can only suspect that it differs based on the part code as there are multiple and they are paired to the fuel pumps part code, all have been discontinued and superseded by denso, presumably because of this fault. if anyone else is reading here because of the same issue, check the fuel pressure sensor for the values above, if you can hear the rear fuel tank pump priming and are getting diesel upto that pressure valve (remove it, dry it, install, prime, remove, check for wetness) then you do not have an issue with the rear pump, if the pressure sensor readings are good, chances are its what is knows as your pressure discharge valve/suction control valve. I'll post more on fix:

well I've fixed mine and returning here to post how! I've tested the resistance on the fuel pressure sensor ( on the fuel rail ) and it was fine and within spec, the problem I had was the pressure discharge valve/ suction control valve - the thing that lives on the back of high pressure pump attached by allen keys- the values that I had for resistance didn't match what I was told is the correct readings, however, even the replacement valve had the same 'incorrect' readings, so maybe that changes based of the part code and pump used. removing the valve can be done easily with engine in, however, the replacement part that I sourced through a local diesel specialist was actually longer than the original, so re installation required undoing the engine mounts from below the car and jacking the engine up and giving it a wiggle to be able to reinstall the new one- fiddly but much easier than removing the whole engine to replace the pump! the reason it's now longer is that the original lexus part and pumps are actually discontinued from denso and to make things complicated, those valves are paired by part code to the fuelpump part codes, so you can't just take a valve out of a breaker car if the pump part code doesn't match. knowing the part codes (black sticker ontop of pump and an etched code on back of sensor) I was able to get a valve for use on the newer revised high pressure pump- even the specialist who sourced this suggested the pump would be required aswell... after a prime for 2 mins it fired straight up, so despite what lexus and specialists will tell you, you do not need to replace the pump at a cost of £1200. you need a £120 part. if you happen to have this problem remember that the pumps and valves must match, so people breaking them sell the whole pump assembly, which given this is a common problem I wouldn't suggest saving money there, especially when you think that it will require the engine to be removed to even get the damn pump off!

results attached. so do we think that its the suction control valve then? Called one breaker and he wants the price of what a whole second hand pump goes for! From what I understand they are specific to the pump used, so I've removed the valve from the car and will do some googling on the codes to see what I can find.

Thank you so much for that, will test tomorrow, is there a workshop manual online for the pressure readings and other sensors? priming on the dash switch I can hear the tank pump working, no noise I can remember from the pump on the engine my suspicion was with that pressure discharge valve, but looking at the space available I don't think that'll come out without removing the whole pump. I'll report back with the findings (really, I will) Thanks again!!!!

this seems to be a very common discussion on the internet but not a single person returned and posted what fixed it for them.... this car just wouldn't start one morning, cranks fine, it's not battery or immob or anything like that. checking the car over there is no pressure getting to injectors and the engine will fire if some brake cleaner is squirted into the intake- so it's a fuel delivery problem. started from the back first, I've replaced the in tank pump and filter, still no difference, without chucking money at parts in the hope of fixing it, has anyone who has fixed this issue or knows of the fix got anything documented somewhere or values for sensors to be tested? thanks.

did the fuel pressure sensor fix this for you??? is this the sensor on the high pressure pump or the rail? any help is appreciated, replaced the in tank pump and filter and still have no pressure to the injectors.

is anyone going to post how they managed to fix this?????