Twin pump fuel supply

Sam44

Member +
Definitely agree the rrfpr I've seen come into its own when set to to hit high pressure at around 3.6bar using the standard 4efte ems and standard injectors with engine breathing mods. The fse rrfpr could drop the fuel pressure to around 2.6bar which kicked off the out of boost proformance. The next very good mod was the inline vacume chamber smoothening out the pressure increase to help match air delivery.
Also agree I've read alot of mixed opinions on the kemso pump. This is why when the 2x new walbro GSS342 arrive I'll fit 1 unit and test to see how it fairs against the kemso.
I could really benefit from a better/higher resolution fueling table. At present I'm 16x16 correction table on the aem piggy back. this has contributed to the out right frustration using the rrfpr.
The 1 Toyota item that delt with the initial open throttle increase in fuel pressure was the corolla tubular inlet flowing great Low rpm inlet charge Velocity almost meeting the sudden pressure fuel increase\raise in injector flow rates perfectly. This can also be seen on the 4efe Dyno graphs 1200rpm to 3000rpm against the ep80 gi graphs. Also very noticeable on the wideband gauge (very readable threw sharp throttle hits).

As always there are many ways to tune I've not had an issue with topend fueling until going over 210hp estimsted, on the tdo4hyb. so yep this is for the bigger hiters UNLESS??
I'm predicting that if the injector duty cycle requires droping across the full rpm range (in and out of boost) once I've install the 2nd walbro pump on the already set state of tune, and not just the problematic topend pressure then this in its self means that nearly all setups will benefit from this mod (improving injector efficiency/duty/delivery)

I've ordered the Evo MK4 fuel filter this filter is a bolt on mod and higher supposed flow rates. this before anything will be installed and tested.
 
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Stu-

Member +
Yes both pumps have a check valve on their outlets before the Y block. The lift pump from the factory tank is a high flow low volume unit and in those setups was just set as on/off.
 

Sam44

Member +
Yes both pumps have a check valve on their outlets before the Y block. The lift pump from the factory tank is a high flow low volume unit and in those setups was just set as on/off.
Thanks for the reply stu. I've ordered 2x check valves also. I'm modding a starlet tank sender unit tomorrow to house the two walbro pumps. Meanwhile I've been doing some research on the various in tank pumps available
The kemso unit has very good reviews.
 

Stu-

Member +
No worries! To be honest I think a decent aftermarket ecu will help solve a lot of the things you talk about.

I'm pretty sure the currently offered Walbro pumps are pretty good! I had quite a few experiences of them failing or poor flow rates vs advertised but that was years ago. I tend to use Aeromotive or DW for high pressure applications these days unless a customer supplies a specific pump. I've got a single Aeromotive Stealth unit in my own car - quiet and flow rates seem to be good for the power its making.
 

Sam44

Member +
It's been a frustrating ride with the piggy back for me, the amount of times I've needed that in-between block on the correction tables. Piggy backs are handy to a point.
This hyb turbo has really impressed me. With every mod it just gets stronger.
There is a mega squirt v3 stand alone ems here waiting, with the later 4efe waste spark corrola crank trigger.

Just time at the moment, but with the state of the airospace industry I might have quite a bit of time on my hands soon.
The kemso pump from what I have been reading on the "internet" is produced by aromotive with the tests I've seen showing identical results. Made me think I should have bought another kemso, always the case.

I will be checking and adding if needed higher current capable electrical parts and larger diameter wire if required. I will report back on this.

I was seeing the walbro GSS342 pump is around mid table.
It will be interesting to see how the twin pumps influence the air flue ratio and if it affects things threw the full rpm range

These lads first recommended twin intank pump upgrades to solve the high rpm fuel problem.

Here is some of the research I found (website list bellow I'll add to as I find them)

 
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Jay

Admin
I'm midway through an overhaul on an EP82 fuel system. Plan was to just replace like for like stock items but this thread has got me thinking.. (thanks Sam)

In terms of future-proofing a vehicle would it be wiser to ditch the stock tank and lines completely and opt for aftermarket components? I had always classed motorsports items as overkill but you fellas are making sense that I probably shouldn't ignore.
 

Sam44

Member +
I'm midway through an overhaul on an EP82 fuel system. Plan was to just replace like for like stock items but this thread has got me thinking.. (thanks Sam)

In terms of future-proofing a vehicle would it be wiser to ditch the stock tank and lines completely and opt for aftermarket components? I had always classed motorsports items as overkill but you fellas are making sense that I probably shouldn't ignore.
I've hit a definite fueling problem jay. I could just cover it up by dumping more fuel in there but it's not how it's been built or the reason it's being built. The fuel filter also ads quite alot of heat due to its location.
 

SKINY

Lifer
Are you thinking track slag Jay :) standard tank cut open and baffled and a walbro pump might do
But then I've seen that kit lol,
Wasnt our Phil selling a cell a while ago.......
 
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