1975 240D Auxillary Fuel Pump Veggie Oil

I installed the mercedessource auxillary fuel pump 3 years ago, works great. Just got car back from mechanic and now the pump is constanly clicking every half second to one second. Like it's not building up pressure.(He should not have been anywhere near the pump or wires) Before it would click fast until it built up pressure then slow down to one click every 1-2 seconds. No leaks, so fuel is not being pumped out. Car runs fine but the pump isn't performing like before. What should I to look for?

Forums

SVO Fuel Conversion Specific Aid

Chassis Model Number

W115

Normal

Clicking is normal. Under normal diesel fuel operations the pump will click every second or so as excess return fuel is moving back to the fuel tank. Most SVO conversions run the fuel in loop mode (no return). When that occurs the pump will build up pressure and the clicking will slow down to a crawl. Check your fuel hose or valve routing.

1975 240D Valve Routing Loop

I think I've narrowed it down to why my fuel pump is clicking faster than normal. It looks like the mechanic re-connected the hoses incorrectly to the 3-way valve, after working on my car. Both positions routes the fuel back to the tank rather than a loop. My question is: When the fuel is in a loop, how much pressure is in the fuel system? My concern is that if I route it like I think it should be for a loop, it's not going to build abnormal pressure and blow hoses and seals out, is it? I thought the most pressure was only about 9-10psi, is that correct?

Keith

10 psi is ok

That is why we sell a pump that only delivers 10 psi. This low pump pressure will not present a problem in loop mode.