double pumper wot fuel presure problem????

[bird]

hey guys! installed hood mounted fuel presure gauge. went for some test runs. on one walbro 340 at 17lbs of boost at wot fuel presure was steady at 58psi. whith both pumps(both walbro 340's) on at wot with the same boost, fuel presure is still at 58psi. if you turn the 2nd pump on at idle fuel preusure raises about 15lbs. why doesnt the wot reading go up when 2nd pump comes on ????? anyways i decided to bench test the pumps, noticed one pump is flowing a little more than the other and they both leak fuel at the electrical connector(where the two male plugs meet the plastic body of the pump) one pump leaks more and oddly enouph its the one that seems to be flowing better. is this normal????both pumps are brand new. anyone have a similar experience????

 

[azgn]

the reason fuel pressure goes up at idle with the second pump is you are overwhelming your return line.........not enough fuel being used by the engine.....at WOT (or somewhere in between) your fuel pressure should just track boost, not increase because of the second pump

if you see higher than normal fuel pressure with two pumps, something is wrong and it isn't the pumps

the idea behind two pumps is to maintain volume, not to affect fuel pressure......fuel pressure is controlled by the regulator, not the pumps

 

[BobbyBuick]

yea what he said exactly.mine jumps 20lbs at idle .

 

[bird]

thanks guys. the reason i even really questioned the wot presure is because the pumps are actually leaking at the electrical connector and i thought they might be losing some flow. anyone know if these things are actually supposed to leak anywhere except the outlet??? im going to call walbro on monday. i was also wondering how much more psi will it increase with boost for example at 25lbs of boost as apposed to 17???

 

[gofastr]

the pressure should rise 1PSI per 1lb. of boost increase, I believe.

 

[Intercooler]

What setup from what vendor? My ATR has an aluminum coupling. No problems detected.

 

[bird]

thanks for youre input guys.i set up the double pumper myself using the atr coupler. the pumps were bought from a local vender(agistino racing here in toronto)I dont have any leaks from the coupler. they are both hotwired, the 2nd pump is on a hobbs switch. the leak is coming from the actual housing on top of the pumps were the male electrical connectors come through the plastic(check my original post)maybe this is normal im not sure. maybe one of you guys have one you can bench test and let me know if it leaks too? too.

 

[lazaris]

You ever discover if this was normal?

 

[87GN_70GS]

the pumps are actually leaking at the electrical connector

That's the bypass or relief valve. Should open under pressure, should be closed with no backpressure on it. When you tested it how much pressure (load) was on the pumps?