After 15k still problems.

fuel accumulator

 

Or even just the one way valve on the outlet of the pump.

Remember, services do not include ANY repairs. It's just preventative maintenance and adjustments. Sometimes you get lucky, but you cannot assume this.

What are your gas analyser readings at the service?

 

I would guess it's something to do with the ignition system. The fuel accumulators as previosly mentioned would not have a significant effect on starting, as they are simply spring loaded diaphragms. Their job is to keep the system pressurized for a time after shut-down, and to smooth out fuel system pressure pulses caused by the fuel pumps when running. I think it's more of an electrical/high-resistance problem somewhere when hot. A sensor(s) or ignition coil?

 

I feel your pain; had the same problem, by changing the fuel pump fixed my misery, also check these threads
Peter



http://www.ferrarichat.com/forum/showthread.php?t=34979

http://www.ferrarichat.com/forum/showthread.php?t=57211&highlight=hot+starting+problem

 

If it is ignition, the most likely culprit is the cranks ensors or their connections. Checking resistance at the ECU connector will be a quick diagnosis, but you can start by checking the sensors directly if you don't have the wiring diagram.

 

So what is "cooled off" after 30 minutes that makes a difference? On some cars, if the fuel lines get hot, you'll get a sort of vapor lock that hinders fuel flow until the fuel lines cool down. It could also be any component from the fuel pump to the fuel accumulator to (presuming you have fuel injection) the fuel rails to the fuel injectors.

I've thought about doing to my Ferrari 348 what I did to my Porsche 928...by going back to Home Depot, picking up some $3 "air conditioning" insulation, and wrapping those self-adhesive gray "tubes" around the fuel lines and fuel rails in the engine bay...just as preventitive maintenance.

Engine hood insulation would probably work, too...instead of the gray home air conditioning tubes.

Keep some heat away from your fuel lines and fuel rails and I bet that your hot-start problem disappears.

 

Low fuel pressure due to internal leak at accumulator or check valve. If you don't maintain sufficient pressure in system, you get vapor lock.

To check electrics you could remove one spark plug lead. Get a spare spark plug and attach to lead. Ground plug body to block using jumper cables or whatever you have on hand. This should be done when engine is in a 'no start mood'. If you are getting a spark at the plug when you crank, then problem is fuel related. My bet is that it is fuel related.

 

I see, instead you want us to take an extra amount of our time to write it up special for you. We've already written down several times before.

If you can't bother to search the archives, then maybe you should consider getting a new vehicle & a different forum.

Anyway, a bad fuel accumulator is the most common cause of hot start problems.

 

In reading comments after my previous post...I would like to apologize to ZAN and others who mentioned the fuel accumulator as a possible cause of this problem. I didn't give this possibility enough thought before brashly stating I suspected something ignition related. It does make sense to me now, if vapor lock is occuring. But...aren't there two fuel accumulators on the car though? Unless BOTH were bad, wouldn't at least one bank try to fire up?

 

Only if you also replace the check valve at the fuel pump outlet (which can also cause the supply pressure to drop too quickly after warm shut-off) per Phil's post #3.

On a TR, we've got pairs of accumulators and fuel pump check valves so via swapping you can deduce the bad player, but on the (single fuel supply) V8s, I can't think of an easy way to determine which component would be causing the supply fuel pressure to drop too quickly (if indeed that is your problem).

 

Not entirely. That's just the most common cause of vapor lock. A bad check valve on your fuel pump could cause vapor lock, too...as could hot fuel rails, or even hot fuel lines (presuming that you are driving a fuel injected F-car).

So can a weak fuel pump.

Try to narrow down your problem. For instance, is your car hard to start when hot because the engine is flooded with fuel (i.e. a bad fuel injector) or because no fuel is getting to the engine (i.e. vapor lock)?

 

could also be one or more leaking injectors. Anything that cause a loss of residual fuel pressure could cause a hot start problem.

CIS injectors are a notorious weak point in the system.

The only real way to diagnose this (besides throwing parts at it) is to hook up a fuel pressure gauge and check the fuel pressures (especially the 'residual' or 'rest' pressures.

HTH,

Jeff

 

I had this problem once with a QV I used to own. It was related to leaky injectors. If the injectors are all original, you may very well have one or more leaking. They are fairly easy to remove and can be checked. If you have bad ones, don't bother cleaning, just get new ones. They aren't very expensive as injectors go, but get them from like an MB dealer or independent source. Have then checked before installing. One very good tech told me some are bad right out of the box.

Dave

 

Can you describe the problem a bit more? OK, the car's been warmed up. If you turn it off & then restart within say 5-10 seconds does it fire-up? Is it only a problem if it sits for a few minutes before restarting? This may be relevant to vapour-lock, pump check-valve & accumulator leaks.

Note that when "cold" additional fuel-delivery circuitry kicks-in, which is why some priblems only show-up when warm.

 

The kind of leak that would give you a hot-start problem is often too small to directly see...just the smallest dribble...and I mean the smallest...right after you shut off the engine will cause trouble. So if you've actually *seen* fuel leak out of an injector, I'd certainly replace that one injector (and would probably replace the rest of them while I was at it).

Even if that leaky injector isn't causing you *this* particular problem, it will find a way to bite you on down the road.

Replace your accumulator. Replace your leaky fuel injector(s). Wrap $3 Home Depot gray-colored home air conditioning insulation (or underhood silver insulation) around your fuel lines and fuel rails (just cut holes out for your fuel injectors to pass through).

If the hot-start problem persists, then replace the rest of your fuel injectors and your check valve on your fuel pump.

If the problem persists after that, then replace your fuel pump itself.

 

Just a silly question, but have you tried to start it hot by pressing the accelerator pedal to the floor? That actually works, even on FI cars. If you haven't tried that then do so; might save a lot of money and waiting time.

Ken