2014 RX350 fuel pressure testing
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1st Gear
Joined: Jun 2026
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2014 RX350 fuel pressure testing
Hi. 2014 RX350 that runs excellent...except it cranks a little longer than it should during start. Seems to be more normal when engine is cold. I have read that it is usually caused by the check valve not holding pressure in the fuel line after shutdown.
Is there a way to check fuel pressure on the low pressure portion of the fuel system with either a gauge or an OBD2 scanner? If replacing just the electric fuel pump (not the complete fuel pump/fuel level assembly), will the check valve be replaced? Basically is the check valve internal to just the fuel pump?
Could a separate check valve be spliced in the fuel line downstream of the electric pump (is the fuel line are hard line or something that could slip over a nipple fitting)? I did this on a 1995 Camaro, instead of replacing a very hard to get to pump and it worked perfectly. When pump is good, but check valve is leaking, seems like just adding a check valve may be an option. Thanks!
Is there a way to check fuel pressure on the low pressure portion of the fuel system with either a gauge or an OBD2 scanner? If replacing just the electric fuel pump (not the complete fuel pump/fuel level assembly), will the check valve be replaced? Basically is the check valve internal to just the fuel pump?
Could a separate check valve be spliced in the fuel line downstream of the electric pump (is the fuel line are hard line or something that could slip over a nipple fitting)? I did this on a 1995 Camaro, instead of replacing a very hard to get to pump and it worked perfectly. When pump is good, but check valve is leaking, seems like just adding a check valve may be an option. Thanks!
Intermediate
Joined: Aug 2025
Posts: 275
Likes: 98
From: AB
Hi. 2014 RX350 that runs excellent...except it cranks a little longer than it should during start. Seems to be more normal when engine is cold. I have read that it is usually caused by the check valve not holding pressure in the fuel line after shutdown.
Is there a way to check fuel pressure on the low pressure portion of the fuel system with either a gauge or an OBD2 scanner? If replacing just the electric fuel pump (not the complete fuel pump/fuel level assembly), will the check valve be replaced? Basically is the check valve internal to just the fuel pump?
Could a separate check valve be spliced in the fuel line downstream of the electric pump (is the fuel line are hard line or something that could slip over a nipple fitting)? I did this on a 1995 Camaro, instead of replacing a very hard to get to pump and it worked perfectly. When pump is good, but check valve is leaking, seems like just adding a check valve may be an option. Thanks!
Is there a way to check fuel pressure on the low pressure portion of the fuel system with either a gauge or an OBD2 scanner? If replacing just the electric fuel pump (not the complete fuel pump/fuel level assembly), will the check valve be replaced? Basically is the check valve internal to just the fuel pump?
Could a separate check valve be spliced in the fuel line downstream of the electric pump (is the fuel line are hard line or something that could slip over a nipple fitting)? I did this on a 1995 Camaro, instead of replacing a very hard to get to pump and it worked perfectly. When pump is good, but check valve is leaking, seems like just adding a check valve may be an option. Thanks!
Last edited by 6runner; Jun 2, 2026 at 07:58 AM.
Pit Crew
Joined: Nov 2025
Posts: 146
Likes: 55
From: Palm Beach, FL
If you cycle the ignition on and off 3–4 times before starting the engine, and then start it, does it fire up just as quickly as if you had just shut it off? If so, the problem is 100% due to a loss of fuel pressure.
If you do not smell fuel either before or after starting a cold engine, then the injectors are most likely *not* leaking.
( I had a car where the injectors wouldn't hold pressure and were leaking. The car was difficult to start when cold (due to the loss of pressure, plus the gasoline that had dripped into the combustion chamber from the injectors and hadn't evaporated), and there was a noticeable smell of gasoline. )
The fuel pressure regulator valve (which also functions as a check valve and an excess pressure relief valve) is located inside the fuel tank, within the fuel pump assembly. It is accessible from the vehicle's interior. You can replace it separately; replacing the entire fuel pump assembly is not required.
OE Catalog: 23280-38020 (RockAuto has aftermarket alternatives)
If you do not smell fuel either before or after starting a cold engine, then the injectors are most likely *not* leaking.
( I had a car where the injectors wouldn't hold pressure and were leaking. The car was difficult to start when cold (due to the loss of pressure, plus the gasoline that had dripped into the combustion chamber from the injectors and hadn't evaporated), and there was a noticeable smell of gasoline. )
The fuel pressure regulator valve (which also functions as a check valve and an excess pressure relief valve) is located inside the fuel tank, within the fuel pump assembly. It is accessible from the vehicle's interior. You can replace it separately; replacing the entire fuel pump assembly is not required.
OE Catalog: 23280-38020 (RockAuto has aftermarket alternatives)
Last edited by Alex1989; Jun 2, 2026 at 05:22 AM.
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