Replaced all injectors, worked great but problem reoccouring

Old-Duckman

Member
 SW Pennsylvania USA
Had slow start problem when the car sat for awhile and diagnosed as leaking injector(s).

Replaced them all with VDO brand. That fixed the problem, the car would fire up with no grinding of the starter, no matter the conditions.

Now a month or so later and several hundred miles, the problem is there again. I verified the leak by letting it sit 2 hours after a nice ride, removed the cap on the schrader valve on the fuel rail and pushed down the valve...no gasoline squirted out.

I guess it is possible that a new injector failed but why didn't it fail right from the start? Could there possibly be something getting through the fuel filter that has affected one or more of the injectors?

The car is a 2004 with 59K miles, I doubt that the fuel filter has ever been changed. Would running a tank with fuel injector cleaner possibly help...or hurt?
 
Why would faulty fuel injectors cause the starter motor to “grind”? That sounds unconnected to me :?
Rob
 
Smartbear said:
Why would faulty fuel injectors cause the starter motor to “grind”? That sounds unconnected to me :?
Rob
I guess I didn’t explain that too well. What I mean is when all is right the engine fires right up with minimal starter motor engagement. When the problem is presenting itself, the starter motor must remain engaged considerably longer before the engine will start.

I don’t know if it is doing so to burn raw fuel that has leaked into the cylinder(s) via a leaking injector or if it “cranks” longer to bring fuel up to the fuel rail.

Whatever the case the car started right up with the new injectors no matter how short or long between starts. So I guess there could be a problem other than with the injectors but that would be a pretty coincidental. The fact that the fuel rail isn’t staying pressurized (which I assume it should) points to a leak in the fuel delivery system somewhere.
 
I don't know anything about the Z4 fuel system, but could the fuel pressure be lost via another route, rather than the injectors ? e.g. back through the fuel pump.
 
Rockhopper said:
Who diagnosed leaking injectors?
Several people actually, and once replaced the car started like it is supposed to, irrespective of time sitting and/or outside temp.

That is why I suspect a failed, leaking, new injector. A old Ducati mechanic once told me to “look at the last thing you worked on.” It has only been a couple hundred miles since I replaced them.

If it is not a failed injector I wonder if it could be a fuel filter that has allowed something past it that did something to the new injector. But 59k...you wouldn’t think it would need a fuel filter. though perhaps the 17 years has something to do with that..?
 
Labouring starting can be a sympton of the camshaft sensor going bad, have you had any codes set for camshaft sensor at all?
I failed to plug mine back in when I renewed my CCV system pipes, car laboured when starting, once I realised the sensor wasn't plugged in and I reconnected it first crank starting was restored.
 
Zulu4 said:
I don't know anything about the Z4 fuel system, but could the fuel pressure be lost via another route, rather than the injectors ? e.g. back through the fuel pump.
I wondered that too but when I replaced the injectors the car started like it is supposed to. I even waited a couple of hours and checked for pressure by pushing the Schrader valve and I got a spray of gasoline. I tried that yesterday and got nothing.

IMO the main suspect is a failed injector whether the be failure in “materials and workmanship “ or messed up due to something getting past the fuel filter.

I need to figure out how to determine which injector is leaking so I send it back for warranty replacement. My thought is to pull the plugs, turn the key to hear the pump cycle and check if any cylinder gets wet. I think that should work providing the car doesn’t prime the cylinders when the pump cycles...I would guess that it doesn’t do that.
 
colb said:
Labouring starting can be a sympton of the camshaft sensor going bad, have you had any codes set for camshaft sensor at all?
I failed to plug mine back in when I renewed my CCV system pipes, car laboured when starting, once I realised the sensor wasn't plugged in and I reconnected it first crank starting was restored.

Anything is possible but the fact that the car started as it should once the injectors were replaced, albeit for a relatively short time, leads me to believe that the issue is a failed injector.
 
If the fuel pressure has been lost via the injector over a long period you may be able to notice oil dilution. I had this with an engine whose carburettor float got stuck open. The oil was noticeably thinner and smelt of petrol.
Perhaps you might also find fuel pooling at the top of the affected piston.
 
Turn the key a few times before you start the car, it'll prime the system and should start straight away. If it works pull the injector rail, prime the pump then check for leak down from the injectors.
 
Zulu4 said:
If the fuel pressure has been lost via the injector over a long period you may be able to notice oil dilution. I had this with an engine whose carburettor float got stuck open. The oil was noticeably thinner and smelt of petrol.
Perhaps you might also find fuel pooling at the top of the affected piston.

Yes, diluting the oil is what scares me and why I want to get this problem fixed once an for all ASAP.
 
Haro said:
Turn the key a few times before you start the car, it'll prime the system and should start straight away. If it works pull the injector rail, prime the pump then check for leak down from the injectors.
Thanks. That makes sense and is a better way to determine, if and, which injector is leaking then they way I was thinking.
 
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