Eggbert

This morning something new happened. I turned on the ignition and waited for the oil level to display. During this time there was a clicking noise and it appeared to coming from the fuel pump area. I remember hearing the same clicking when I had my MGB, but it didn't last long and stopped quickly once the pressure built up. For the Cayman (2006) it does tend to fade away, stop very briefly, and then start again.

Now I can see three things that could cause the lack of building pressure:

1/ Fuel Pump faulty
2/ Fuel System leak
3/ Leaky Injector

I suspect #1 to be the most likely, but there's more to the story.

I've ruled out #2 as the driveway is dry under the car.

Now for #3. I did hook my scan tool up yesterday. No misfires had been detected but it had another heading called "cylinder roughness". Not sure what it's measuring, or what units quantify the measurement, but I found something on the net that suggests the cylinder isn't firing cleanly, which could be an injector problem, or valves, or carbon... whatever. 5 of the cylinders showed low readings (like 0.2 or 0.3) except for cylinder #1 which was just over 1.0

Anyway, the car started fine and without any smoke (if a cylinder had excess fuel in there, I would think some black smoke at start-up might occur). I had treated the engine to some fuel injector cleaner and it did seem to fix an initial roughness when first started after sitting, but a wait over-night shows the roughness for the first few seconds when first started (cold) is still there, although improved quite a bit..

Any thoughts on why the fuel pump (if it is that) is clicking and doesn't want to hold pressure?

Edit: I forgot one other thing.... fuel pressure regulator?

Eggbert

Didn't do much so far. But did confirm the clicking is from the pump as it stops when I pull the fuse.

Am starting to rule out pressure regulator as there is no return line to tank for pressure to bleed off in case of a failure.

So,,,, I can plug off the pump output and see if the clicking stops (pressure has built up). If so, replace pump (anyone know of an aftermarket one?) If not, then I'll look at the injectors. Nasty work having to take that intake manifold off....

TMc993

My guess...Given the different reading on the #1 cylinder, I'd tend to suspect that the injector on that cylinder is leaking down and depressurizing the fuel line. The fuel pump ticking is characteristic of the pump building pressure in the system, which it should not have to do if the system was holding pressure.

Eggbert

I agree Terry. There's also a new story to help support that theory. I was out this morning with the ignition ON, the fuel pump clicking away, and it was that way for a little while. During that time some excess fuel did get into a cylinder as when I finally started it, a got a good cloud of gray smoke. (kind of anticipated black, but it's got to be very rich for that).

I ran the engine for 5 or 10 minutes and then shut it off. Turning the ignition back ON, the clicking was gone. So an intermittently sticking injector looks like the best guess. I guess vibration and heat probably helps it unstick.

My next step was to block the pump outlet and see if the clicking went away, but as it's not clicking anymore (at least right now), so that's out. Cant' think of anything else to try, so I might as well replace the injectors. They very well could be the original ones and have 80K miles on them.

Injectors and Intake gaskets.... anything else I need other than patience and perseverance?