Piazza Fuel System

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rodavo
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Piazza Fuel System

Post by rodavo » Thu Dec 20, 2007 2:15 pm

I am in the process of upgrading my fuel pump and I am looking at adding in a surge tank and lift pump as well. The problem is I am trying to work out exactly how the standard Piazza system works.

Is there an intank fuel pump? The Piazza manual doesnt seem to mention one but the way I see it it has to have an intank pump to feed the main pump. Also, if there is an intank pump then what is the purpose of the sub pump that sits next to the main external pump? Is this to remove the vapour from the vapour seperator?

Does anyone know? Bugle I know you have had your fuel tank out?

Thanks

Dave

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Post by wedgenut » Thu Dec 20, 2007 3:39 pm

no pumpy in tanky, just external sucky and pushy
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Post by Rodeobob » Thu Dec 20, 2007 4:52 pm

Theres a fuel system diagram in the manual.

Think its in the emissions section.



The small pump is just a facet carb type it works off the return line i think.
The other pump is the high pressure job.
The smaller pump feeds the return fuel in a circle back to the inlet for the high pressure pump.

They are both in a cradle under the back seat on the drivers side.


Bob.
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Currently unemployed. Watch this space.

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rodavo
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Post by rodavo » Fri Dec 21, 2007 8:01 am

I know about the diagram in the manual. What I am questioning is how the fuel actually flows in the system. I had a look at the sub pump in my car and its got a directional arrow stamped on it, but the arrow is pointing in the opposite direction to the way the fuel should flow if the sub pump was feeding the main pump. This is why I thought the sub pump might be pumping the vapour from the vapour seperator back to the fuel tank and if this is right then what feeds the main pump? It must rely on gravity and its own suction?

Maybe my sub pump is around the wrong way? My main pump has always been very noisy and sounds like it is cavitatingand pumping alot of air.

Dave

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Post by wedgenut » Fri Dec 21, 2007 5:34 pm

Been thinking about your pump issue, i have figured that the OZ YB Piazza must have the I-tec fuel system, same as the yanks got. The UK models had I-tec as well, the reason is this Sub (or boost) Pump as the USA manuals call it. It was never fitted to non turbo cars and it only seems to be fitted to those cars with the I-tec system. All the turbo cars we got in NZ were used JDM imports and they all have the JECS system as far as i know and only one Pump, same set up as the Non turbo cars which are also JECS with a single pump although pressure differs between the two types. I think that is down to the regulator rather than the pump.
So the question i would have to ask is whether or not it is actually needed or is it just some more whale saving environmental crap that was fitted to export model cars, probably driven by bloody californian regulations or some other such zippo bullshit.
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Post by Bugle » Thu Dec 27, 2007 12:54 am

Nah Australian ones have ECGI, dunno about JDM fuel systems have a look on the right side just infront of the rear axle for the tank and pumps. All I know is they changed to in tank pumps in 88 which I guess removes the sub pump if it ever had one.

Yeah the main pump uses its own suction to lift fuel out of the tank. Ill have a look at mine which way the sub pump goes but I always thought its job was to pump fuel into the little tank out of the return line to keep it full. Wouldn't make sense to pull fuel away from the main pump?

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Post by wedgenut » Thu Dec 27, 2007 4:58 pm

Nope only one pump on our cars (JDM's). ECGI as far as I know is a trade name used by Bosch for the injection system part of the party trick and nothing to do with the ECU directly i don't think. Our cars are also ECGI injection but the ecu is still JECS and not I-tec. According to the YB manual yours are I-tec so that will be the reason for the extra pump on your models, different ECU. As i said earlier the yankee doodles have the same set up on their version and so does Europe. It is starting to look like the JDM's are the only ones with single fuel pump and JECS ECU.

Here is an extract from the patent registry pertaining to fuel injection.
"Fuel injection for internal combustion engines offers several important advantages over the conventional method of carburation. One such fuel injection system known as the Bosch ECGI-system employs electromagnetically actuated injection valves and solid state circuitry for the metering of the injected fuel volume. The system is a pulse-timed manifold injection system, whereby the fuel is injected onto the heads of the intake valves by electromagnetically actuated nozzle valves."
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Post by Bugle » Fri Dec 28, 2007 9:07 pm

Nah Australian ones definitely have ECGI, the ECU is made by JECS. Uses a flap airflow meter and the ignition timing is mechanical except for knock control. The YB service manual calls it ECGI too.

I-TEC (Isuzu Total Engine Control) is made by Hitachi and does all the injection and ignition timing along with a CAS type dizzy, uses a hot wire airflow meter.

Maybe the extra pump does suck vapour out of the little tank there and is a measure to stop 'vapour lock' getting to the fuel pump. Might be another one of those hot environment things they did for Australia and the US like the injector cooling fan.

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Post by wedgenut » Sat Dec 29, 2007 8:24 am

Well bugger me he said, there you go then, the Europeans definitely have the I-tec ECU. The only ones we had here with CAS dizzy were the DOHC's and they are fairly rare. We should ask 117coupe he'll bloody well know why coz he is a fountain of knowledge. So apart from the injector fan and the extra pump I wonder what else is different on the YB's to ours? Oh yeah you have the different diff same as the poms.
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Post by Bugle » Sat Dec 29, 2007 11:34 am

We got water cooled turbos too I think I read JDM ones never had that?

Yeah we got the handling by lotus diff, you got a Gemini diff in most of yours, too bad :finga:

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Post by 117Coupe » Sun Dec 30, 2007 10:10 am

Bugle wrote:We got water cooled turbos too I think I read JDM ones never had that?
JDM models got the water cooled turbo with the '88 minor change update which started in August '87.
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Post by Rodeobob » Mon Jan 14, 2008 3:31 am

rodavo wrote:Maybe my sub pump is around the wrong way? My main pump has always been very noisy and sounds like it is cavitatingand pumping alot of air.

Dave

Will check for you tomorrow if i rememeber.
If i dont get on my case.

Bob.
Too many Piazzas to little money.

Currently unemployed. Watch this space.

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