Mondial fuel pumps

K-jetronic fuel pumps only come on when the air mass plate senses air flow (i.e. engine turning over)

 

I thought they came on when the ignition is on, hence the buzzing noise behind you, when I had a problem with my starter motor the tone of the buzz dropped when you turned the key as the power was being drained from the pump to the starter

 

No, Russ is right. Fuel pump only pumps when the engine is turning otherwise the injectors could be spraying fuel when the engine wasn't turning. BAD.

 

Ah I see, so whats the humming/buzzing noise behind you when you first turn the ignition prior to starting??

 

they do start once the key is turned; engine not turning, the metering plate controls the fuel flow. the injectors won't spit fuel unless the plate moves. there is also a redundant sensor to make sure the fuel only suplies via plate movement when the engine is running. think accident, engine stopped pump on.

so i usually will turn the key to the first stop to get the pump on and system pressure up then kick her over to start.

 

Hey all,

Cool thread! I just had my 30k on Rachel (92 Mondial t, Valeo Cab) and, all of a sudden, I'm hearing a whurring, electric motor kind of sound, in a fairly constant frequency range - not in sync with engine RPMs - just behind and below my head (left side). There's no connection to my AC, radiator fans or anything else that I could readily identify. Has anyone ever experienced this one?

Cheers, Hank

 

On similar lines I started a thread about an uprated Mondial fuel pump (see link), but no-one has answered, so can I presume that there are no options

http://www.ferrarichat.com/forum/showthread.php?t=114491

 

injectors not squirting unless airflow moves the control plunger in the metering head is right. When the plunger is at it's rest position, it cuts off flow to the injectors. You should be able to run the pump all day with the engine off and not fill the intake with fuel.

the schematic, however, says that the fuel pump should only run in two situations:
1] airflow switch is open, which happens when air is being sucked into the intake...or someone unplugs the switch
2] the ignition key is in the cranking position.

having said that, I seem to recall that my old girlfriends '80 308 fuel pump is powered with the key in the run position. That implies at least one of the following:
1] the airflow switch is effectively stuck open
2] the "engine start" relay is not powering when it should. This relay is called all sorts of things in later cars.
3] wire/connector problem
4] I can't read a schematic
5] ferrari can't assemble it like they designed it

I'll have to check next time I'm over at her place.

attached is a schem chunk from 1981. When there is airflow, the fuel pump relay is powered via the yellow circuit. No airflow, and the engine start relay closes, so fuel pump relay power has to come from the red circuit from the ignition switch.

the yellow circuit would also need to be +12V when cranking to power the engine start relay. The 328, modial and mondial qv have a similar circuit.

the airflow switch is really protecting against a fuel line rupture. If that happens, the engine should die from fuel starvation, and the airflow switch would indirectly cut off the fuel pump. If you happened to be cranking when the fuel line pops, you're screwed. The pump will still be running, and if your exhaust is hot, you may have redefined the term "portable grill".

testing can be done without a meter. Figure out what the engine start relay is called in your car. When you turn the key to the run position, it should click closed, but the fuel pump/relay shouldn't run/close. Disconnect the blue airflow switch plug on top of the fuel distributor, engine start relay opens, fuel pump relay closes, fuel pump runs forever.

cranking is a bit trickier, but you are looking for the fuel pump relay to close when cranking. If you crank enough to get some airflow, the engine start relay might chatter as the airflow switch opens/closes, but in either position the fuel pump relay should be powered. Probably easier to verify with meter.

If you have to excessively crank to get started, the red circuit and cold start injector fuse is a good place to check.
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on the mondial wiring diagram, there is a key activated relay that signals the bridge relay to start the pump. in other words on the first key stop the pump is on, then on the cranking stop the pump is bridged to stay on. on the distribution block there is a circut/sensor that will cut power to the pump in the event of a roll over.

but as we know ferrari electronics are as reliable as lucas, okay they don't leak oil as bad bosch made the FI and ferrari installed it. germans and itailans working together.

 

Frequency valve? Not sure. I don't hear anything on mine.

Birdman

 

frequency valve,
in abs cars, the abs pump will come on initially as well

 

interesting...which mondial is that?

oddly, I had to pop over to the ex's to look at a problem with one of her cars today, so I checked the 308. In this case, her pump is running with the key in the run position because of a bad wire between the engine start relay and the airflow switch on the fuel distributor. In the above schematic, the purple wire.
It's never grounding, so the engine start relay never closes.