Depressurising fuel rail between runs.

[StrongSpearWorks]

While I wait for new injectors, is there a quick and easy way to depressurise the fuel rail to stop my cylinders filling up with petrol between runs?

Pull fuse 1 and let it stall, clamp the fuel line before the rail?

All that petrol down the cat and in the oil can’t be doing anything any good!

[bob12]

SPW - I have been looking, albeit briefly, at your two posts about your typical start issue across these engines. There doesn't seem to be any mention of the fuel preesure relieve valve (FPV) on the end of the fuel rail.

These start/non-start problems are typical and over comeable but, have you changed the FPV?

Just a thought.

Bob

[StrongSpearWorks]

Originally Posted by bob12

SPW - I have been looking, albeit briefly, at your two posts about your typical start issue across these engines. There doesn't seem to be any mention of the fuel preesure relieve valve (FPV) on the end of the fuel rail.

These start/non-start problems are typical and over comeable but, have you changed the FPV?

Just a thought.

Bob

I’ve pulled the vac hose off and it’s dry, so the diaphragm is intact. Can it go bad in other ways? I have a spare one I could pop on, but that’s unknown and untested.

[Forrest]

The conventional methods to depressurise the fuel rail are either to pull the fuel pump fuse with the engine running or to release pressure by applying vacuum to the fuel pressure regulator once you’ve switched off the engine. I don’t think I’d want to do either of these routinely though.

[StrongSpearWorks]

Routinely… no, but might be worthwhile for the next few days?

[Laird Scooby]

Originally Posted by StrongSpearWorks

I’ve pulled the vac hose off and it’s dry, so the diaphragm is intact. Can it go bad in other ways? I have a spare one I could pop on, but that’s unknown and untested.

With the engine running?

From all the symptoms you appear to have, it's unlikely to be the FPR, more likely dirty injectors causing poor sealing when allegedly closed allowing fuel to drain through and flood the engine.

Try some Comma Injector Magic or Carlube Fuel Injector cleaner through it before you start faffing about pulling fuel rails apart.
Alternatively about 100ml Carlube ATF-U or NAPA MVA added to the fuel tank will do a similar job.

[lynns hubby]

I seem to recall a valve with cap on, just like the tyre type valve on the fuel rail on my previous 940s. I used that to depressure the fuel rail when I needed to. Rag round it and a small screwdriver to push pin in gently. Obviously with ignition off. It automaticity pressures up when you turn the ignition on.

[StrongSpearWorks]

Originally Posted by lynns hubby

I seem to recall a valve with cap on, just like the tyre type valve on the fuel rail on my previous 940s.

I've heard of this, but mine does not have that valve, which would have been handy in this scenario.

[StrongSpearWorks]

Originally Posted by Laird Scooby

With the engine running?



Try some Comma Injector Magic or Carlube Fuel Injector cleaner through it before you start faffing about pulling fuel rails apart.
Alternatively about 100ml Carlube ATF-U or NAPA MVA added to the fuel tank will do a similar job.

Picking some up tonight... fingers crossed. I don't particularly want to be faffing with a fuel rail this weekend - weather looks awful!

[StrongSpearWorks]

Well… I used to consider fuel additives as snake oil, but I tell you what, no more hard starting, misfires and smoke, idle is smoother and I swear the fuel pump doesn’t make as much complaint.

Thanks for the tip Laird!