All of the fuel that goes to the IP has to pass through the tank filter, the Walbro filter, the main factory filter and then the strainers in the injector line. It's quite a bit of resistence. If the Walbro is blocked then the IP is certainly going to grunt a bit. Cleaning it is necessary.
Now why fit one? I first fitted one when I built the off roader. When we used to park at craxy angles at Lincomb, most of the trucks struggled. THe IP was lifting fuel almost vertically over a distance of several meters. Keeping the engine running was tricky at times. So I fitted one and it cured it. Under normal circumstances, completely unnecessary.
But I have fitted one to the overlander. Huh? Well it gives me the practical function of being able to dispense fuel easily, say into cans or another vehicle. I can empty the tank to save fuel if I have a leak and of course in the event of a misfuelling. I can also use it to transfer fuel from one tank to the other if necessary. I have already used it in Russia. At one point we were not allowed to fill cans and as we needed to fill up for a long and remote trip, I filled the cans from the pump and then went to the garage and filled the vehicle. We never found out why, but some places got very cross indeed when we tried. Oddly the ones that sold Jerry cans....
www.joint-torique.com
