i tested 2 of their 340 pumps and they both gave me lower base pressure after install. first one i tested was the one with the wide center bottom unit. that one didnt work for me on the dyno so i exchange it for another 340 pump that was identical to my walbro 255. where the bottom is the same as oem. i install that and still same the same. i have my base fuel pressure set at 55psi with the 255. when installing each of the 340 pumps. these pumps made my base pressure drop to 51psi. so i didnt bother using the unit. anyone test them and notice an improvement? are the base pressure suppose to be lower? from the flow chart i would think it should be higher right off the back. i was expecting the pressure to hop 60psi +. knowing its a way higher pressure pump.

 

Anyone try any of the 340lh pump? Did it make a
Different?

 

need help on reading the flow chart. does it mean that at lower pressure the pump will produce max pressure. so for base pressure should be better at 35psi?? i dont know how to download the flow chart here but. it shows that at 35psi it flows 340lph and it drop as the pressure goes up. so if i have my base pressure set at 55psi. it show on the chart that the pump is flowing at 300lph. at 55psi. so is it better to set the base pressure lower or im just not reading it correctly???

 

flow chart link:

http://treperformance.com/files/TRE340LPHFlowChart.jpg

 

The pump doesn't make pressure, your pressure relief valve does. So if your PR valve is set to 55 psi, regardless if you're running a walbro or a weldon, your fuel pressure should be 55 psi. (If the pump is WAY oversized, then you can expreience pressure creep at idle, but that's a whole different topic and obviously not the issue here).

Pumps move volume. The restriction from the PR valve is what creates the system pressure, and the lower that pressure is, the more any pump will flow.
Low pressure = light load on the pump = high flow volume
High pressure = heavy load on the pump = low flow volume

It's like putting your thumb over the end of a garden hose: you can get it pretty tight and build up pressure in the hose, but hardly any water makes it past your thumb. Or, you could barely have your thumb over it, and have a lot of flow, but no pressure in the hose. Fuel systems are exactly the same.

I would guess:
1) those pumps simply don't do what they're supposed to do
2) you have a pick-up or plumbing issue with it installed
3) you have a wiring /voltage drop issue with it installed

Can you easily hotwire the pump to run constantly key-on, engine off?

For the record, this is the first time I've ever heard of tre and "their" pumps, but if they really flow ~330 lb/hr at 100 psi (like their flow chart specifies) - these are monsters.

 

I have a relay on the pump also. With the 340 pump and at a base pressure of 75psi my tuner couldn't get any full pulls on the dyno without fuel problem. After switching back to my walbro 255 there was no more fuel problems. Set the base pressure at 55psi and dyno session went ok. Ran out of injector so had to stop. Getting this 340 pump was to get more hp out of my setup and had it retune. Sent the pump to get tested just incase I got a bad one and was tested good by them. One thing I was thinking of trying was putting the 340 pump back and lowering the pressure to 40psi if the pump flow more at a lower pressure, but I know I will need a retune. If I'm planning to boost around 25-28psi boost , where should I set my base pressure? Since the more you boost the more pressure it will go up and less flow the pump will provide.