348 spider hard starting

Thanks for the kind words, and yes, you are correct that my experience is extremely limited...

My theory on depressing the clutch was that engaging the clutch **might** make the necessary difference in reducing flywheel vibrations when the grease was marginal. That theory might be flawed. Apologies there if so. Harmless test, though. 348 hard to start? Put her in gear and try to start with the clutch fully depressed. Starts?! Great. Not?! No harm.

The other test would be to spray starter fluid directly into the cylinders. If the car starts and then dies you know then that you have a fuel starvation issue.

Finally, I'd pull one spark plug and briefly crank the engine...so as to identify if I have a spark issue.

The "flywheel grease" theory is a spark issue. If you have a spark, then the flywheel grease can NOT be your problem. Limited experience or not, I'm confident on that point.

 

348's should **always** start on the first crank (never more than 20 seconds, typically less than 5).

Your new fuel pressure regulators may have solved one problem, but from the above I'd hazard a guess that they are set to too low a pressure instead of 54 to 59psi.

Either that, or else you are perhaps turning the ignition key directly to Start instead of switching it first to Run for a few seconds prior to Starting.

 

I haven't tested to confirm this, but the Workshop Manual says that the fuel pump is actuated by the ECU when the engine speed tops 30(that's thirty)rpm, so the fuel pump apparently does not start building pressure until the engine is actually cranking over, and the one-way valve on the pump does not open to release fuel pressure into the system until the pressure in the pump exceeds 21.3psi. There is a pressure relief valve in the pump which shuts the pump off if an obstruction causes the fuel pressure to reach 113psi.

 

No-Doubt... just because there is spark (and fuel) does not necessarily mean it will start.

The spark with a rattly flywheel could be at hopelessly the wrong time.

And Miltonian is correct... the pumps won't run at all until the engine turns.

 

I didn't know all of that, thanks. Yet another thing that I would have lost money on a bet about. I pretty well learn one or more new thing about my 348 from F-Chat each day.

Moreover, that's counter-intuitive. Typically the fuel pump turns on when your key reaches Run (charge the fuel rails)...now, thanks to you and FerrariFixer, I know that our 348 fuel pumps don't first turn on until after we hit the Start position.

That pressure sensitive fuel pump cut-off function is cool, too.

 

I agree. You need spark, proper fuel mixture, and timing.

As for the fuel pumps not running until **after** the engine has made some turns, would it be fair to say that this acts as a pre-oiler for our 348's??

I'm thinking that one of our oil pumps is chain driven from inside the engine, so surely some oil is moving during those engine revolutions prior to the fuel pumps kicking on.

It would be sweet to nail down that functionality so that the 348 Brotherhood could point to a pre-oiler being on our cars.

Another point that needs nailing down is whether the ECU's are delaying BOTH spark and fuel pumps until after so many revs. Before your post above, I was reasonably confident that the flywheel grease vibrational problem would prevent a spark...now it seems as though it prevents fuel...BUT...does it prevent both spark and fuel?

This is important as it bears on which tests need to be performed to correctly diagnos a flywheel grease problem. If we see a spark, do we know that it isn't a flywheel grease problem, for instance?

 

No doubt

You're obviously very keen to know as much as possible, and already know a great deal, but when offering advise maybe just hold back on your factual content and offer it as opinion or thought.

The fuel pump delay is a safety thing. If you crash badly and the engine stops, the fuel pumps will stop to avoid feeding the fire..... It's not a pre-oiler.

All of the oil pumps are chain driven.. one off the back of the other by a peg drive.

During cranking with a rattly flywheel, the ECU is not really delaying anything due to the fault... it's not that smart... it just doesn't know what to do and when. The cam shaft mounted phase sensor tells the ECU when to inject (which stroke the engine is on), the crank sensors tells it how long to inject for and when to spark.

 

Perhaps it is not a pre-oiler per se, but aren't you getting that same effect?

As you point out, both of our oil pumps on our 348's are chain driven off of the engine (one from the back, one from a "peg"). So when our engine first begins to turn, those oil pumps likewise must surely start to pump.

Yet you also pointout that our fuel pumps aren't pumping until after our engines spin up a bit.

Well, isn't that what a pre-oiler does...flow oil prior to the engine actually starting?

If our engines have to reach 30 RPMs before our fuel pumps even come on, and if our pressure valves don't open until some time after our fuel pumps have charged up our system, then in that period of time our chain-driven oil pumps have been flowing oil prior to the engine starting, yes?!

A miniature pre-oiler, then!

 

No. It takes several seconds to build oil pressure. The car starts well before that when healthy... just watch your oil pressure gauge and you'll see.

No pre oiler... sorry.

 

You and the workshop manual are probably correct...but man...I had it stuck in my head that the WM said to turn the ignition key to the Run position to perform the fuel flow test. Surely we aren't supposed to test the fuel flow by starting the engine.

Though apparently I'm wrong about that per your above reference to the factory workshop manual. Bizarre.

 

OK, thanks. So no oil is flowing prior to the engine starting on a 348, if I correctly understand you above.