Dual Facet Fuel Pumps

you may want to read this thread first

http://www.ferrarichat.com/forum/206-246/372894-new-fuel-pump-setup.html?highlight=fuel+pump

 

I've corrected the setup, since Tony posted out that my assumption about the resulting pressure was wrong, against a single Hardi 18812 pump.

Next to the gasing/thermal problems in which the Facet seemed to have at least a part, i feel that the Facet red tops are way too noisy for my taste. The original Bendix double pump setup was less noisy from what i remember, and the BCD Corona in later models was also quite acceptable but both are not available anymore. One Facet Red Top is quite sufficient in any case, i currently run a Facet red top in a 5.3L V8 Aston Martin until the factory double SU pump setup has been restored.

Next to the Hardi 18812 the Mitsuba pump seems to be a good alternative, same principle so not much noise to notice.

 

Difficult to say from your description but vapour locking is caused by fuel vapourization in the fuel lines and / or carb bowls through heat. Try not redlining it 11K and the problem will be halved!!

If you get it started then I doubt its fuel lock. Does it do it from cold?

Is fuel circulating around the system, imo the Facet pump is to big for the dino V6 but

It could be ignition related, advance not working, what ignition do you run? My car suffered with similar problem and it was the coil getting to hot.

Adrian (alhbln) is the wizard on these issues especially if you have the old MM system and dizzy.

 

Driving or being stuck in traffic in a hot climate (35ºC and above, depending on the fuel quality) can lead to vapor lock symptoms with the Dino, as the gas tanks share the engine compartment. Depending on the pump type you can get vapor lock symptoms already at a lower temperature or have no issue at all even with 35ºC. I had severe vapor lock issues on the highway at 32ºC and above using a Facet red top, while the 246 GT behind us with the original double Bendix setup had no problem whatsoever. We were using the same fuel.

Vapor lock can feel like a rev limiter or broken/weak ignition, where the effects get more pronounced and will set in at lower RPMs, while the fuel heats up and vaporizes. Usually, after 1/2 hour of parking the car, the fuel should have cooled down sufficiently to not cause vapor lock effects anymore.

There is a simple test, which you can do when your tanks are only 1/3 full. When the effects kick in you described above ("intermittently running out of fuel"), drive to a gas station and fill the tank up to at least half capacity. This will cool down the existing warm fuel in the fuel system, so there won't be any vapor lock effects afterwards.
If you now still have the effects as described above, then there might be a problem with the filter, carbs or a thermal defect of the ignition or coil.

Question, how do the plugs look like? whitish/brownish or dark/sooty?

 

From memory the Facet Red top pump (FRT) delivers about 125litres/hr and is more than capable of dealing with the V6 thirst, incidentally similar as the original twin bendix setup, however the pressure it develops within the system is to much, typically 6-8psi. Now considering the existing Bendix pumps operated at a max pressure of 4psi, then the carb and fuel system set up was not designed to cope with that 100% over design. The excess pressure in the system can cause fuel to spill past the float and cause all manner of problems. Having said all of that i have a FRT pump and never expereinced vapour lock or carb issues.

The fuel system is designed on a continous loop and therefore any unused fuel is deposited back into the tanks. You will not get much heat soak from the tanks as i beleive the original coating material had insulating properties and therefore mitigated the heat soak from these. Non metallic flex hoses are used throughout the system to prevent / minimise the effects of heat soak as well.

So the pump circuit which is under postive pressure would be unlikely to cause vapour lock throughout the circulation system as it can self vent. The area at risk is the fuel bowls especially the one over the water thermostat housing, this can boil the fuel dry, however as soon as the pump is switched on then it will fill up.

Float levels on the dino are critical and therefore extreme care must be taken in setting these up.

If you are getting symptoms of fuel starvation while running at high speed check for blocked filters (inc the FRT pump), incorrect carb settings etc. Faulty ignition can cause similar symptoms.

 

Based on my driving experiences your are spot on! Never chimed in on vapour lock discussions, cause I don't know what happens in 120 degree days, and never sat the car for hours in such hot climes. My thinking is that it would just boil the floats dry faster.
Where does the evaporated fuel vent to? Thin air?

 

That's the problem when the engine is switched off and you get heat soak from the engine, it can boil dry the petrol in the bowls.

However if this happens when parked then the float/s will drop and the vapour is vented into the carbs throats through the main jets.

As soon as you turn on the ignition, the pump will refill the chamber again and purge the fuel system. Starting should not be a issue so long as you give them time to refill. The whole system is self venting so should clear any airlock.

If it happens when driving then its turning to vapour quicker than the pump can deliver fuel......time to get out of the car!

Fuel pumps can have intermittent faults, they are a positive displacement pump and can fail on the top end of their performance.

 

I know exactly what you mean by this, Adrian helped me out with my ignition coil issues. After a short run the car felt like it was running out of fuel and would then just snap back into life. I would just drive straight home.

It turned out the coil was the wrong type for my ignition setup and was breaking down. Not saying this is the case with your problem but I have learnt to never discount anything. Another issue I had was the charging, the ammeter was always fluctuating, I suspected the VR and changed it, but many months of investigation it turned out to be a poor soldered connection at the battery.

Can you explain "weird" in a bit more detail. Sounds like something could be breaking down.

Dinos are difficult to start when hot though but they don't run weird ;-)

 

Electrical gremlins would result in wet plugs not slightly sooty plugs
Weird running after sitting for 1/2 hour and hot?
No spitting back, no misfire no popping exhausts
Something flooding maybe.
Does it happen every time, or was this a one time event?
Has it ever run right?

 

So you then leave it until its cold(say 4+ hrs or more) get in and drive it no problems, switch off, leave it for 1/2hr, restart and problem re-appears?

Cutting out smoothly suggests electrical breakdown somewhere, gas running out would be a momentarily jerky shut down as each carb is starved of fuel.

 

hope you sort it out, next time it happens, check for sparks.
the only issue I have ever had is similar, turned out to be electrical

 

Intermittent dropouts are diffficult to diagnose by looking at the plugs. What happens if you switch to the ignitions 'Emergenza' setup as soon as the problem sets in, do you still have the same symptoms or is all working fine now?

 

This is interesting because I recently had a lead core plug fall out of a carb. When I repaired it I had symptoms similar to those that you describe. engine was fine when cold but ran badly when it was left to stand and re-started. What was even odder was that when I left the engine to go really cold e.g over night it started and ran fine again for the first 10-15 miles.
after going through the ignition I eventually removed the carb and all was revealed- loads of debris in the float chamber. I presume that rather than the problem being temperature related it was sediment getting shaken up related and this must have been muck from the core plug failure.
perhaps you just have some muck in the carbs?

 

Yes, that might be quite possible considering the age of the electronics and components by now. I would recommend switching the ignition off before changing from Normale to Emergenza mode.
If your Dinoplex features a switch then you have a AEC101 (large box) as installed in L and some M Series Dinos. Those can be easily repaired if there is a problem.

Good luck,
Adrian

 

if you found sediment in the float chambers recently it will be almost certainly be deeper in the interior of the carbs. I would just strip them down and give them all a good clean and eliminate it from the enquiry. The engine will only run better anyway for a clean.

 

Agree wholeheartedly with that advice, but I feel the sudden shut down to be more in line with electrical failure than fuel. Fuel starvation, blockage etc results in lean conditions with popping, snapping back through the exhausts / carbs, backfiring etc as the engine scavenges for fuel before eventually shutting down.

symptoms before can be a good clue as to whats going.

 

Something has to be eliminated from the list.
Based on the description, it is a repeatable event, in which case,
my suggestion.
Carry a spare sparkplug. Take a passenger slong for the ride
Next time car will not start, remove one of the plug leads
Attach the spare plug and make sure it makes contact with some metal part,
cylinder head is fine. Have passenger turn the starter and watch for sparks.
No spark, its an ignitiom issue.

Sparks but no go? Fuel delivery problem, check fuel pump
Do you hear it whirring ticking etc

And so on