Thread: TD5 fuel pressure and install of gauge fittings

Good choice of beverage!

Back on track, what pressure do U exepect to see on the return side?

I had a pressure gauge temp mounted in the fuel temp sender hole as I was diagnosing a possibly failed pump, 65psi give or take.

A guage in the return line after the regulator may show low fuel pressure if the regulator fails or the strainer blocks but wont help indicate pump pressure/operation is normal?

And I dont think legally one can mount a mechanical fuel pressure guage inside the cabin of modern cars due to inherent risk of fuel leak

On the return side should be the difference between the pump's output which is between 4.5 - 6.5 bar and the regulated rail pressure of 4 bar so a gauge there will show between 0.5 and 2.5 bar and i dont see the relevance of that reading, for fuel pump HP output check IMO it's enough to fit a T piece like this https://www.merlinmotorsport.co.uk/p...-1-5-tp-m12x15 for the temp sensor and a switch like this https://www.merlinmotorsport.co.uk/p...i-set-m-ops-35 connected to a LED in a visible place on the binnacle, this way if the pressure drops below the preset limit you'll have the warning...or if you want to be scrupulous you can fit a pressure transducer and a gauge which doesnt imply fuel in the cabin

giving my experience on road trains nearly all fuel pressure readings are taking after the head before any regulator


is best to measure fuel pressure in the head than measuring before the head other wise why not install a gauge at the pressure side of the fuel tank
why measure fuel line pressure when you can measure injector pressure


the flow direction on the td5 pressure regulator the return goes back to the regulator housing this holds pressure in the head before sending back to tank


the only reason I installed a pressure gauge is that my fuel pump has been screaming like a cat for 9 months I wanted to test pressures before purchasing another pump lucky I found this forum and it actually turned out to be combustion washers (learn something new every day) normally on roadtrains the combustion washers allow fuel to bleed back and I never had fuel back issues


I do have gauge temporarily installed in the cab ,,,and to be honest I like it,,, my pump is that silent the pressure gauge tells me otherwise


with ignition on only the pressure reads 55 psi
with engine idling pressure is 55 psi


while driving and on boost pressure drops to 50 psi minimum


off the accelerator and then is sits back at 55psi


ps cold mornings first start up I have seen 60 psi or just shy of 60 psi
I can only put this down to the regulator opening up more once warmed up and fades off to 55psi @ idle

Originally Posted by geordiepride

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the flow direction on the td5 pressure regulator the return goes back to the regulator housing this holds pressure in the head before sending back to tank

You are right, i stand corrected...didnt think of the flow just concentrated on the "return" thing... yes you should have HP at that position cos it's before the FPR valve is releasing the excess back to tank

Can I ask why?