Fuel Pressure Regulator (1 Viewer)

[robnicko]

quick question pls

I have a feeling my FPR is playing up, 1FZ-FE
Symptom - Sunday here was 38deg C and we were travelling back home when I slowed down to take a turn up a incline, doing about 20kph i accelerated and felt like it was bogging down (rpm's were about 1500 and auto trans was in 2nd gear). It felt like I had to really press the accelerator almost to the floor and then it slowly picked up and then seemed fine after that. Really felt like it wasnt getting any fuel.

Ive tested and confirmed the FPump, CORelay and fuel pump relay are fine and even cleaned the fuel pump relay contacts which were pretty clean anyway.

No CEL, stumbling or anything

I unplugged the vacuum line on the FPReg and no visible fuel in it but it did smell of fuel. I also noticed the top hat of the FPR where the vacuum line connects can be turned left & right and unsure if this should be able to or is it not the case.

I dont have access to a pressure gauge to connect inline however given its the original FPR and not far off 600 thou kms any thoughts?

Rob

 

[Pippylongsausage]

Change your fuel filter. I’m not sure about the reg rotating but there’s plenty of more likely causes. A fuel pressure gauge will tell the whole story. Also fuel pumps can do funny things when they begin to fail.

 

[mudgudgeon]

The fuel pressure regulator will turn if the nut locking it down isn't tight.

I agree with checking/ changing fuel filter too

 

[robnicko]

The fuel pressure regulator will turn if the nut locking it down isn't tight.

I agree with checking/ changing fuel filter too

I checked it last nite and nipped it up slightly - it is original so was probably just recompressing the O-ring - no leaks from it though

Going to do the fuel filter this weekend and see how that goes. Odd thing was it hasnt happened since and when it did happen was a very hot day (38 deg) AC on and accelerating from a slow speed. Felt a bit like when you run out of fuel and then fuel comes in and power restored. Was only a momentary thing & hasnt happened since & tank was over half way full.
I do have another fuel pump which i keep in the drawers with a spare starter (no auto roll start !) so will do the fuel filter change 1st and see - process of elimination at this point as no code was thrown

 

[TomH]

@robnicko any updates? Your problem description sounds exactly like what I'm seeing on my Land Cruiser. I plan to check fuel pressure this weekend but was curious if you've resolved your issue.

 

[TomH]

I'll just take over this thread. Had some time after work to hook up the fuel pressure gauge. I mostly followed the FSM and checked the following pressures:
Idle: 34 psi, no spec for this measurement
Idle with pressure regulator disconnected: 42 psi, spec is 38 - 44psi
Idle after reconnecting pressure regulator: 36 psi, spec is 31 - 37 psi
5 minutes after shutdown: dropped to zero almost immediately, spec is 21 psi minimum Edit - pressure drop was due to faulty gauge pressure release

Fuel filter was replaced about 9000 miles ago (last June) when I did the head gasket.

Really leaning towards fuel pump. Any thoughts?

 

[robnicko]

@robnicko any updates? Your problem description sounds exactly like what I'm seeing on my Land Cruiser. I plan to check fuel pressure this weekend but was curious if you've resolved your issue.

hi Tom

yes and it wasnt the FPR.

Sheepishly I will say that a new Air Filter was in order. Once I replaced it the issue hasnt reappeared and the 80 has a lot more pep and better fuel economy
The dash indicator never lit up indicating it was not flowing properly but it has made one hell of a difference with the new one, OEM of course

 

[TomH]

hi Tom

yes and it wasnt the FPR.

Sheepishly I will say that a new Air Filter was in order. Once I replaced it the issue hasnt reappeared and the 80 has a lot more pep and better fuel economy
The dash indicator never lit up indicating it was not flowing properly but it has made one hell of a difference with the new one, OEM of course

Interesting. I checked my air filter and it is dirty but didn't think that would be the problem.

 

[robnicko]

Interesting. I checked my air filter and it is dirty but didn't think that would be the problem.

I too was surprised as the old air filter looked great on the inside and outside was dark which i cleaned as best as i could. It wasnt till i got the new one that I realised how clean it should have been. Lesson learnt for me in that they dont last forever even with regular blowing out etc

 

[jonheld]

5 minutes after shutdown: dropped to zero almost immediately, spec is 21 psi minimum

Possibilities:
Faulty check valve in the fuel pump
Leaking injector(s)
Faulty FPR
Fuel leak

 

[TomH]

I too was surprised as the old air filter looked great on the inside and outside was dark which i cleaned as best as i could. It wasnt till i got the new one that I realised how clean it should have been. Lesson learnt for me in that they dont last forever even with regular blowing out etc

Looks like air filter was my problem too. I swapped the filter from my LX450 into the Land Cruiser and the problem seems to have disappeared. The only reason I'm still skeptical is the LX450 isn't showing the same problems with the Land Cruiser filter. Maybe because the LX is about 1000 pounds lighter. Two new filters are on order. I suspect there will be a run on air filters after people read this thread.

Possibilities:
Faulty check valve in the fuel pump
Leaking injector(s)
Faulty FPR
Fuel leak

You forgot one possibility, faulty pressure release on the gauge. When I did the initial tests, the needle on the gauge was very stable and the it held pressure after 5 minutes. I did a retest and the needle on the gauge was jumpy and it didn't hold pressure. Based on this and the fact that I didn't check with the fuel pump powered but engine off, I decided to recheck this morning. I pulled the fuel pump relay, which was a pain because it is buried under my added fuse box, and jumped pin 3 to power.

Results all look good to me, a little high but I think that is better than low.

FP on, engine off: 47 psi, spec is 38 - 44 psi
Idle with pressure regulator disconnected: 45 psi, spec is 38 - 44psi
Idle after reconnecting pressure regulator: 36 psi, spec is 31 - 37 psi
5 minutes after shutdown: 36 psi, spec is 21 psi minimum

FP on, engine off

Fuel pressure regulator vacuum disconnected:

Fuel pressure regulator vacuum reconnected:

Engine off after 5 minutes:

Jumping FP relay: