Hey guys! can I run dual stock lift pumps? I am getting my new one (new good one, long story) tommorrow, but I cleaned the filterscreen out on my old one &amp; it runs great, so I was wonderign what if I put thenew one up front &amp; the old one out by the tank &amp; just run a wire off the harness on the other lift pump??<br>What do you all think!<br><br>DRecu!

 

Some people are having great success with a simular setup that you are describing. If I were in your shoes, I would mount the new one by the tank, and get rid of the stock one.<br><br>The PE4200 is what i will be going with soon. <br><br>Andrew

 

How about two parallel, maybe each with its own pull line? Hey, both at the tank.

 

2 factory 15psi lift pumps in a pusher configuration would be to much pressure. IMO

 

Well sometimes I am not too smart about things but I sort of figured that a pump regulated at 15 pounds is prone to failing and does not keep the 15 pounds under load so another pump in parallel with its own suction line would produce 15 pounds as regulated and double the volumn of the fuel.<br><br>But it seems to me that two pumps regulated at 15 pounds would not produce over 15 pounds if in parallel or series.

 

You are correct HID, two pumps rated for 15 lbs each would not produce more than 15 lbs no matter how they were hooked up. Considerable more volume of fuel but not any more pressure. The way the pumps work is they shut off at a regulated pressure, no matter where the pressure comes from. If 15 lbs is the limit for the pump then it cant pump at all if there is already 15 lbs on the line. <br>Hope that makes sense :<br><br>Keith

 

Thanks Keith

 

2, 15 psi pumps in series will yield in excess of 20 psi at the VP44 pump.

 

[quote author=StakeMan link=board=4;threadid=7170;start=0#68854 date=1037662604]<br>2, 15 psi pumps in series will yield in excess of 20 psi at the VP44 pump.<br>[/quote]<br><br>Why I thought the ECM limits the fuel press. if I tied them off the factory harness both should run in sequence &amp; they will just run half time cause they will build pressure faster? Wrong?? Right??<br><br>DRecu!

 

If you add a 7 psi Carter pump at the tank you will have 22 psi at the VP44.

 

Stakeman,<br><br>Sorry, but you just cannot &quot;add&quot; pressures together for hydraulic systems. The lower pressure pump will stop pumping at 7psi and just recirculate the fuel inside the pump. Only the higher pressure pump will pump to it's set pressure. Then it's own relief valve will open and divert the fuel to keep the pressure at the set 15 psi.<br><br>Mariner.<br>

 

[quote author=mariner link=board=4;threadid=7170;start=0#69266 date=1037722711]<br>Stakeman,<br><br>Sorry, but you just cannot &quot;add&quot; pressures together for hydraulic systems. The lower pressure pump will stop pumping at 7psi and just recirculate the fuel inside the pump. Only the higher pressure pump will pump to it's set pressure. Then it's own relief valve will open and divert the fuel to keep the pressure at the set 15 psi.<br><br>Mariner.<br><br>[/quote]<br><br>Is that right? I think NOT. I have (had, unitl yesterday) a pusher (7psi), with my factory lift pump, when first installed I had 20psi prefilter, and 21 psi post filter, as of late, it was upto 30-31psi, BTW yes, I have 2 gauges both mechanical and accurate, no electric sender BS.<br><br>Now I installed an entire new fuel system, pump, lines, fittings, retaped the tank, the whole ball of wax, and have a steady 21 pre, and 20 post, and NEVER drops below 16psi, even at WOT.<br><br>Some of you guys need to get your facts straight, before you post.<br><br>Later, Rob

 

Well all i'm trying to ask is would'nt I have constant pressure since the ecm controls the pumps, I am not going to rewire the whole system I am just going to take the orig. lift pump wire &amp; splice into it so it will still work with the ecm as being 1 pump. why would this make ym pressures too high?

DRecu!

 

[quote author=TxDieselKid link=board=4;threadid=7170;start=0#68428 date=1037585208]<br>Some people are having great success with a simular setup that you are describing. If I were in your shoes, I would mount the new one by the tank, and get rid of the stock one.<br><br>The PE4200 is what i will be going with soon. <br><br>Andrew<br>[/quote]<br><br>well the old one still works so I would like to use it, but what if I have the old one in the stock location &amp; then put the new one buy the tank, the new one would do the work to get it up to the old one so the old would not have to work nearly as hard to get the fuel up, I think it's a great idea........<br><br>DRecu!

 

The ECM only limits fuel pressure when the motor is starting. It does this buy running the lift pump at a lower duty cycle.