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[malcy]

Normally my 1997 2.5 V6 Omega CDX starts within seconds at the first attempt.  However if I do not use the car for several days starting becomes a problem.  It takes 3 or 4 attempts with 5-10 seconds of engine cranking each time before it will finally fire.   From then on, until the next period of extended inactivity, we are back to normal.

The behaviour is as if the fuel is draining back and the system is having to re-prime itself.   Is this possible?

Any ideas as to how I might resolve the problem ( which is admittedly relatively minor at the moment, but there is always the fear that it will get worse   )

[JamesV6CDX]

If you're not starting it for days at a time, and it starts within a few seconds of cranking, that's not a big problem.

You may have a leaky injector (s)

[TheBoy]

If you crank it for 5s with throttle fully depressed, then try to start normally, is it OK then?

[malcy]

I think that as I try to start when it is misbehaving I am putting my foot to the floor progressively during the cranking period, ending fully down for the last couple of seconds.   I will have to wait until I come back after a few days without use the try putting my foot fully to the floor for the whole of the 1st attempt, and then try normally for the next.

I will post again when I have that opportunity.

[TheBoy]

I think that as I try to start when it is misbehaving I am putting my foot to the floor progressively during the cranking period, ending fully down for the last couple of seconds.   I will have to wait until I come back after a few days without use the try putting my foot fully to the floor for the whole of the 1st attempt, and then try normally for the next.

I will post again when I have that opportunity.

OK, let us know how you get on.

Cranking at full throttle disables the injectors, so doing this will clear flooded cylinder - eg, if you have leaky injectors.

[Sir Gingerlot]

I was under the impression that just switching the ignition on primes the fuel pump. Next time try leaving the ignition on for a few seconds before trying to start and see if this helps.

[malcy]

Tried again this morning.  This time I left the ignition on for about 5 seconds before starting, engine fired up immediately.   So Ong's suggestion that this will prime the pump seems good - thanks.    

Since this behaviour is new (for the past 10 years the car has always started first turn of the key without me having to waut for 5 secs) does it imply that the pump is getting tired and about to fail?

[Martin_1962]

Fuel filter?

Leaky injectors?

[TheBoy]

Leaky fpr?

[malcy]

Excuse my ignorance but fpr?   Please can you expand the acronymn.

[Kevin Wood]

Excuse my ignorance but fpr?

Fuel pressure regulator.

It's a cylindrical valve at the end of the fuel rail which maintains a constant pressure (usually around 3 bar) of fuel in the rail that feeds the injectors. This is achieved by diverting excess fuel back to the tank via the return line.

If this has become leaky it will result in the fuel pressure bleeding away when the engine is stopped (normally considerable fuel pressure remains between engine starts) and slower priming of the fuel system when the engine is restarted.

There is a schrader type valve at the rear of the fuel rail, under the plenum, where a gauge can be connected to check the fuel pressure. It might be worth taking the cover off this and pressing the valve plunger after the car has been sitting idle for a few days (before turning the ignition on!). You should get a squirt of fuel if the rail is still under pressure.

Kevin

[TheBoy]

Excuse my ignorance but fpr?   Please can you expand the acronymn.

Sorry, I should have explianed  

As Kevin Wood says, Fuel Pressure Regulator - designed to keep fuel rail at constant pressure so ECU knows exactly how long to hold injectors open for....  ...but if faulty (or another leak in fuel rail/injector etc), pressure will drop over time when switched off...

[malcy]

Thanks for the detailed advice about the fpr.    I have proven over the past couple of days that by turning on the ignition for 10 secs or so prior to starting then I get immediate firing - every time. So this seems to reinforce your theories about loss of pressure through either the fpr or an injector.

I have lost the car to my brother-in-law for a week, as soon as I get it back I will check out the pressure as suggested.   If it is leaking away over a few hours I guess the next problem is to isolate whether it is an injector or the fpr.   I do not think it is a fauly joint or leaking pipe - there is no smell of petrol or evidence of a leak.

Thanks again for the info - will post again when I have more info to share

[Kevin Wood]

Running the ignition for a while does sound like the fuel pressure is not coming up as quickly as it should.

In addition to the items mentioned, it could be a lazy fuel pump, bad connection in the wiring to it or a clogged fuel filter / crushed fuel line.

Does the engine run OK under full load or does it stumble if given flat out acceleration?

Kevin

[TheBoy]

Running the ignition for a while does sound like the fuel pressure is not coming up as quickly as it should.

In addition to the items mentioned, it could be a lazy fuel pump, bad connection in the wiring to it or a clogged fuel filter / crushed fuel line.

Does the engine run OK under full load or does it stumble if given flat out acceleration?

Kevin

A lack of fuel supply (as caused by pump/filters etc) would more likely affect running, not starting, wouldn't it?