Stupid Doubt about FMUs
03-17-2006, 03:48 AM
#31
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Join Date: Apr 2005
Posts: 375
Re: Stupid Doubt about FMUs
woo we are actually having a serious discusion on HMT open forum. Some pretty smart guys here.
Thats a good idea with the fuel line will try it.
Ok this is the setup.
Orignally the fuel pump that came with the car was 4 PSI. Its an in tank electrical pump.
Since this is a total Getho setup we hit the junk yard and looked for Used Electric Fuel Pumps from another car which was EFI. We found two one that made 45 PSI and one that made 35 PSI. I got to keep the 35 PSI pump. The logic was carbed setup. We only need boost + 4PSI. So even at 16 PSI we only need the pump to do like 16+4 PSI.
The pump was installed in the tank. And the FMU spring was set so that output without boost is 4 PSI.
Now to answer your very inteligent question about where the FMU signal is refrenced.
Last night as I sat looking at the setup I was thinking the same.
Basiclly you have 4 locations to pick for your FMU and BOV refrence.
You can use a point in the pipeing just before it hits the carb. Thats where my Boost gauge is hooked up.
You can use the point which controls the vacum advance. Or you can use a point just above the buterfly or just bellow the buterfly. Or off the manifold.
Im pretty sure we tested each and every point and finally picked a point just above the buterfly on the carb to refrence the FMU and the BOV the same line is split to the FMU and the BOV.
My Boost gauge is hooked up the the tubing after the intercooler as is my BOV (The Physical BOV not its refrence line).
My Plan of action for today.
1. Experiment with more tubing from the FMU to carb
2. Measure the Vacum and boost at all the posible refrence points. And note them down Im pretty sure we allready did this during the install.
3. Consider geting a better Fuel Pump. That puts out at least 50 PSI.
4. Chk the FMU to make sure its really working
5. Consider buying one of those fuel pump with FMU and gauge for like 25$ on ebay.
6. Dig out Corky Bell and all the other Turbo Books and see what they recomend for carbed setups.
One issue that worries me is that the hole dia on the FMU fuel out is smaller than the combined dia of my Jets. So maybe I need to drill that hole out a bit but that would upset the pressure setings right.
Thats a good idea with the fuel line will try it.
Ok this is the setup.
Orignally the fuel pump that came with the car was 4 PSI. Its an in tank electrical pump.
Since this is a total Getho setup we hit the junk yard and looked for Used Electric Fuel Pumps from another car which was EFI. We found two one that made 45 PSI and one that made 35 PSI. I got to keep the 35 PSI pump. The logic was carbed setup. We only need boost + 4PSI. So even at 16 PSI we only need the pump to do like 16+4 PSI.
The pump was installed in the tank. And the FMU spring was set so that output without boost is 4 PSI.
Now to answer your very inteligent question about where the FMU signal is refrenced.
Last night as I sat looking at the setup I was thinking the same.
Basiclly you have 4 locations to pick for your FMU and BOV refrence.
You can use a point in the pipeing just before it hits the carb. Thats where my Boost gauge is hooked up.
You can use the point which controls the vacum advance. Or you can use a point just above the buterfly or just bellow the buterfly. Or off the manifold.
Im pretty sure we tested each and every point and finally picked a point just above the buterfly on the carb to refrence the FMU and the BOV the same line is split to the FMU and the BOV.
My Boost gauge is hooked up the the tubing after the intercooler as is my BOV (The Physical BOV not its refrence line).
My Plan of action for today.
1. Experiment with more tubing from the FMU to carb
2. Measure the Vacum and boost at all the posible refrence points. And note them down Im pretty sure we allready did this during the install.
3. Consider geting a better Fuel Pump. That puts out at least 50 PSI.
4. Chk the FMU to make sure its really working
5. Consider buying one of those fuel pump with FMU and gauge for like 25$ on ebay.
6. Dig out Corky Bell and all the other Turbo Books and see what they recomend for carbed setups.
One issue that worries me is that the hole dia on the FMU fuel out is smaller than the combined dia of my Jets. So maybe I need to drill that hole out a bit but that would upset the pressure setings right.
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