Walbro 190, is it enough? Options

[ncgalant]

I'm assuming your 190 is rewired. My 255hp is not rewired and I'm running 22psi with no fuel issues(going to rewire soon). My 255 that is not rewired shouldn't flow all that much more than a 190 that is. Am I making any sense?

As for the 2g MAS, I'm pretty sure people go that way because it is larger and counts larger amounts of air without hacking. Also being larger the spool is slightly better. You do have an SAFC in there right?

[turbohcar]

Depends on your fuel pressure. Without knowing your fuel pressure it's like trying to play paintball with a blindfold on. You might get lucky you might not. As a rule of thumb your fuel pressure should always be 10psi higher than how much boost you're running. Your setup with fuel pump and fuel pressure regulator will determine fuel pressure. Plus you have to have the injectors to flow all that fuel. Sorry if this feels like a dead end but until you know pressure, you're shooting in the dark.

[natedogg]

A 190 matched to 550's with a 2G MAS, hmm. It would probably work. But a 255 with an AFPR and 550's controlled by a MAFT or SAFC/2g MAS combo would work better, but that gets a litte more expensive. I've never had any personal experience with a 190 beyond the tuning that I have done with Marcus in his car. I've heard that it is supposed to flow more fuel at near stock pressures though. The 255 on the other hand flows even more while raising the fuel pressure beyond stock which is why an afpr is recommended to bring the fuel pressure back down to stock levels and tune the injectors through some kind of fuel control. I guess its a case of doing things the less expensive and easier way, or the more expensive and 'right' way. Bold statement DSM forum, I know.

ncgalant- Your 255 will flow more than a 190 even if its not rewired. It also raises your fuel pressure beyond stock especially when it is rewired. The easiest way to tune with it, especially with your big 720cc injectors, is to bring the fuel pressure back down to stock levels with your afpr (get a fuel pressure guage! ) and let your safc do the tuning with injector duty cycle. One can raise or lower the fuel pressure to get a bit more or less fuel per pulse, but when it starts getting to high or too low the spray pattern can change into something undesirable and less fuel atomization is achieved. This can cause bad gas mileage, stuttering, misfires, bad idle, plug fouling, and worst of all knock.

[ncgalant]

Well I now have the pressure down quite a bit more. Chris I think you were right about the pressure being way to high. I know have it down loads and my car's pulling much better. I also turned the boost back down until I can build or get a boost controler that is better.

[awd4kicks]

Here is some pertaining info from RRE... Also check out the very informative graph found at vfaq.com attached!

In 1996 we did some research into Denso's (formerly Nippon-Denso) in-tank fuel pump flow rates. The biggest surprise was how much voltage affects flow. Also how much flow drops off at higher pressures.

If you measure the available voltage at the battery with the engine running you should see 13.5-14 volts or so. If you then measure the voltage at the fuel pump it's self with the engine running, it will be around 11.9 v and with the fuel pressure regulator loaded with boost pressure the voltage drops to 11.8 v. This is from the small gauge factory wiring being unable to handle the current. The fix for this is to run a large (10 ga. or more) wire directly from the battery to the fuel pump.

To do this you'll need a 30 amp relay (Bosch part #0 332 204 150 or Hella part # 960 388 07 or Porter & Brumfield # VF4-45F11) and the relay wiring harness for it. Any 30 amp 12v relay will work. Try an alarm shop or stereo shop if you have difficulty finding the correct relay. We use a heavy-duty fuse holder with a 30 amp fuse right off of the positive terminal of the battery. Attach the fuse holder to the positive terminal of the battery. The other end of the fuse holder goes directly to terminal #30 (power in) on the Bosch style relay. From terminal #87 (power out) on the relay run the big 10 ga. wire back through the fire wall, under the carpet towards the back of the car. The color for the positive wire to the fuel pump will vary some from year to year. The wire color also changes from one side of the connector to the other. On the car side of the connector the wire will almost always be black with a white stripe. Occasionally it is blue with a white stripe. The large all black wire is always ground. The positive wire will be the other thick wire. Smaller yellow wires are for the fuel level gauge and the low level warning light. Once you go on the fuel pump side of the connector, the positive wire is usually blue.

Front wheel drive (1G) '89-'94
Run the wire to the driver side rear seat floor. Pull out the seat bottom and pull back the carpet where the back seat passenger would put their feet. You will see a wire harness running through to the fuel tank area. Poke the new fuel pump wire through this grommet. Go under the car now and carefully run the wire along the other wires and cables with zip-ties. You need to route the wire to the rear center of the fuel tank. There is a round black connector with 2 wires, cut the blue wire and connect the new larger wire to the wire running into the fuel tank. Tape up and protect the unused old wire.

AWD (1G) '89-'94
Continue running the new larger wire all the way (inside the car) to the driver's side rear corner (driver side of the spare tire). There is a plate that unscrews to access the fuel pump, remove it. Cut a small hole through the grommet and run the wire through the hole. Cut the black wire with the blue stripe and connect the new larger wire to the wire running into the fuel tank. Tape up and protect the unused old wire.

FWD and AWD (2G) '95-'98
Lift up the rear seat bottom cushion. On the passenger side there is a metal plate screwed on, remove it. Cut a small hole through the grommet and run the wire through the hole. Cut the black wire with the blue stripe and connect the new larger wire to the wire running into the fuel tank. Tape up and protect the unused old wire or use it to trigger the relay.

All 1G
An easy way to trigger the relay is to use the fuel pump check connector located on the wiring harness that runs along the firewall. You will see a single black connector that is taped to the wire harness near the battery. This connector gets power when ever the fuel pump should be on. Run a wire from this check connector to terminal #85 on the relay. From terminal #86 run a ground wire. If your relay also has a terminal #87A, ignore it (not used). Use care with all connections that you make, these are important wires !

1G AWD all 2G
You may find it simpler to install the relay close to the fuel pump. An easy way to trigger the relay is to use the old fuel pump voltage input wire to trigger the relay. The old small wire gets connected to terminal #85 on the relay. From terminal #86 run a wire to ground. Tuck the relay under the safely under the plastic 1/4 panel inner trim.

With this modification you should see 13.8-13.9 volts at the pump with a good charging system. This allows the pump to pull an additional 5 amps at idle. The electrical system is designed to operate at this (14 v) voltage. Denso fuel pumps are designed with this voltage in mind.

As you look these specs over you can see how it is worthless to compare fuel pump flow with out specifying both voltage and pressure. Lph = liters per hour. All Denso 50mm (1G) and 38mm (2G and GVR4) Dia. in-tank fuel pumps start out with the part number 195130-xxxx

T/E/L turbo stock pump, GVR4 and 323GTX too: $20 used good
(1G and 2G both even though they are different sizes)
part #s: -0510, -0153, -0670, -0440, -2020, -0022, -2760 :
100 lph @43psi @12v 70 lph @58psi @12v
140 lph @43psi @14v 110 lph @58psi @14v

RRE In Tank Upgrade Pump and most all Denso In Tank Pumps: $165
part # -0990:
150 lph @43psi @12v 120 lph @58psi @12v
210 lph @43psi @14v 170 lph @58psi @14v

Toyota Supra Twin Turbo In Tank Pump (Adj FPR required)
260 lph @43psi @12v 220 lph @58psi @12v
290 lph @43psi @14v 260 lph @58psi @14v

Three other pumps worth mentioning are:
Mazda RX-7 Twin Turbo #-0782 210 lph @43psi @12v
Mazda Cosmo, (HKS in-tank) #-0771 250 lph @43psi @12v
3000 GT VR-4, Celica GT-4 #-0740 180 lph @43psi @12v
These sound good but their price does not make them a very good value ($275-$400+).

Attached File(s)

 Fuel_flow_graph.jpg ( 0bytes ) Number of downloads: 0

 

[natedogg]

That's good info. I also like dsm-performance's explanation of fuel pumps, afpr's, and injectors:

http://www.dsm-performance.com/fuel_pumps.php
http://www.dsm-performance.com/fpr.php
http://www.dsm-performance.com/fuel_injectors.php

[turbohcar]

Very good info. Thanks AWD4kicks

[ncgalant]

Using the graph, it looks like the 190 should supply 550's to 55psi or so. That is in a perfect world. Using...

.55 L/min * 60 min/hr * 4 injectors / .26 L/gal = 34 galons / hr
That's at 100%DC

Figuring the pump is going to see a higher pressure than that of the rail it makes sense that a 190lph will run 450's right at 100%dc and the 550's around 85%

[wortdog]

I think that graph was done at 13.5 volts. If you can get a full 14v back there, you'd have plenty of headroom for 550's at 58 psi or so. Changing your fuel filter often (yearly on a daily driver) is a good idea too, a slightly clogged filter will really affect flow.

[ncgalant]

Yea, really for that chart to be accurate you'd have to run 3/8 line from the pump to the rail with a k&n fuel filter.