Pagoda SL Group

W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: ryanpe56 on July 24, 2025, 17:34:34

Title: fuel pump volume at return vs outlet
Post by: ryanpe56 on July 24, 2025, 17:34:34

'71 280 SL with rebuilt fuel pump I have 1.3L in 15 sec at the outlet and .56L in 15 sec at the return line. Is this sufficient? I'm trying to solve a 4500 rpm max rev issue. Is the return line compensator adjustable? Is the goal to have 1.5L at the return as well as the outllet?

Title: Re: fuel pump volume at return vs outlet
Post by: Lori on July 24, 2025, 18:04:30

Should be 1l per 15 seconds at the return.  Check the lines first

Title: Re: fuel pump volume at return vs outlet
Post by: ctaylor738 on August 07, 2025, 15:37:03

A flow of .6L / 15 seconds is not ideal but I don't think it would cause your RPM limiting.  I agree with Joe, most likely a bad coil unable to refresh fast enough.

The return flow is not adjustable. There is a spring-loaded pressure valve in the pump's exit, and a diaphragm in the modulator.

The test on the input side is 1.1 to 1.3 bars of pressure measured at the cold start valve.  I undo the line and connect a gauge by pushing a 5/16" fuel line over the line's fitting and securing it with a hose clamp.  The line attaches to a pressure gauge.

Cheers,

CT