Greetings everyone,
Please help. Today I noticed a fuel smell in the cabin. I didn't smell it while driving 15 minutes to my butcher, only after I stopped the car, exited the car, bought groceries, and then returned. In total I was away from the car about fifteen minutes. On return, the smell was noticeable in the cabin. I drove back home and sat with the car while idling. No smell. Stopped the car and waited about five minutes and could smell fuel again. Opened the hood and could smell fuel. Opened the trunk to see if it was an issue with fuel pump or tank, no smell. Obviously, I am concerned.

Over the last couple of days I noticed that acceleration from a cold stop first thing in the morning was a bit sluggish. After the car warmed up, acceleration from a stop was fine. Driving home at the end of the day acceleration from stop is totally normal.

Fuel injector problem? Throttle? Hoses that connect fuel rails?

I have attached a short video of the car idling. It sounds a bit different to normal (clicking), but I may just be thinking that because I believe something is wrong with the car.

Charles

 

Hi Charles,

My first thought is that the fuel pressure regulator diaphragm has failed, allowing raw fuel to be inhaled into the intake manifold via the FPR vacuum hose. This causes the engine to run rich because the ECM is not able to meter this extra fuel that is bypassing the fuel injectors.

While the engine is running, the fuel is burned in normal combustion, so you don't smell the extra fuel. But when you shut off the engine, the residual pressure in the fuel rail forces fuel into the intake manifold, where it pools, and you smell the fumes, either emanating from the air filter housing or from one or more leaks in the air intake plumbing.

A quick way to test this theory is to pull the vacuum hose off of the FPR, crank the engine briefly, then check for the presence of wet fuel at the vacuum hose fitting on the FPR, which indicates diaphragm failure.

If the fuel smell is stronger on the right hand side of the engine, then you could have leaky fuel injectors allowing fuel into the exhaust, but to smell it in the engine bay, you would have to have a leak in the exhaust, possibly due to a cracked manifold or leaking manifold gasket.

Cheers,

Don

 

Dear Don,
Many thanks! Running rich is exactly how the car smells.
Point of clarification: reference to side of engine is from the vantage point of front seats looking toward the radiator? (i.e. left side of engine would correspond to passenger side of RHD car).
I ask because looking from the front seats toward the radiator the fuel smell is strongest on the left side of the engine bay.
Is the fuel pressure regulator the same for both V6 and V12 variants? (EBC2606) My original parts diagram show FPR for the 3.2 and 4.0L versions, but not the V12.
Best wishes,
Charles

 

Hi Charles,

Sorry, I always forget yours is a V12. Yes, I do refer to sides of the engine as viewed from the driver's seat. Here's the diagram of the 6.0L fuel regulator and plumbing from the late XJS parts diagrams. I assume yours is similar. The FPR is Part #1:





You can view the part identifications and part numbers at this link:

https://parts.jaguarlandroverclassic.../brand/jaguar/

Cheers,

Don