Mark Ogram Posted September 20, 2019 Report Share Posted September 20, 2019 Hi, I am trying to adjust the fuel pressure on my TR6 Pi. I have a Bosch pump and Revington diaphram PRV. I cannot get the pressure below 125psi. Instructions that came with the PRV say screw in to increase pressure, screw out to reduce pressure - which does not make sense to me, should it be the other way round ? I have the pressure gauge connected to a tee piece at the metering unit. Ignition on (engine not started). Wire to coil disconnected. Could anyone tell me what I am doing wrong, or has anyone else had similar problems. Thanks. Mark. Quote Link to post Share on other sites
stuart Posted September 20, 2019 Report Share Posted September 20, 2019 That is the correct way to adjust as screwing it in puts more pressure against the diaphragm to increase the pressure. FWIW depending on the pump you may find you need to alter the pressure down to around 95PSI as the Bosch shifts more than a Lucas and will overfuel if pressure is too high. Stuart. Quote Link to post Share on other sites
colin3511 Posted September 20, 2019 Report Share Posted September 20, 2019 Hi Mark, Probably the Malpassi unit. Clockwise to increase pressure setting. Colin Quote Link to post Share on other sites
Mark Ogram Posted September 20, 2019 Author Report Share Posted September 20, 2019 Thanks for the responses Stuart and Colin, Just started the engine- Initial pressure pulsing between 130 / 140. Then dropped to 110 / 120 (without me doing anything) Then pulsed between 60 / 120 (without me doing anything) Then the engine died, along with my enthusiasm. So I guess it's the pump that's knackered ? Cheers. Mark. Quote Link to post Share on other sites
Waldi Posted September 20, 2019 Report Share Posted September 20, 2019 Not necessarily Mark. Did the pump make strange noises (cavitation) and is the battery voltage still ok? Could also be an issue with the PRV. Have you connected it the right way (sorry for asking). Waldi Quote Link to post Share on other sites
AdrianH Posted September 20, 2019 Report Share Posted September 20, 2019 I know it's an obvious question, but have you phoned RTR and asked them? It would be the first thing I did. Quote Link to post Share on other sites
Mark Ogram Posted September 20, 2019 Author Report Share Posted September 20, 2019 1 hour ago, Waldi said: Not necessarily Mark. Did the pump make strange noises (cavitation) and is the battery voltage still ok? Could also be an issue with the PRV. Have you connected it the right way (sorry for asking). Waldi Thanks for the response Waldi, Battery is fully charged. The pump is making whiring noises (pulsing). Yes, the PRV is connected the right way. I do have a pre filter, and a Bosch post filter fitted, will this filter (after the pump) be a problem? Thanks. Mark. Quote Link to post Share on other sites
Mark Ogram Posted September 20, 2019 Author Report Share Posted September 20, 2019 1 hour ago, AdrianH said: I know it's an obvious question, but have you phoned RTR and asked them? It would be the first thing I did. Hi Adrian, Tried to phone Revington this afternoon, no answer. Sent them an email, no response. Thanks. Mark. Quote Link to post Share on other sites
TR NIALL Posted September 20, 2019 Report Share Posted September 20, 2019 18 minutes ago, Mark Ogram said: Thanks for the response Waldi, Battery is fully charged. The pump is making whiring noises (pulsing). Yes, the PRV is connected the right way. I do have a pre filter, and a Bosch post filter fitted, will this filter (after the pump) be a problem? Thanks. Mark. Take some Photos of the Set Up you have we may be able to spot a problem. Quote Link to post Share on other sites
Waldi Posted September 20, 2019 Report Share Posted September 20, 2019 Hi Mark, If the pump is running but making noise with fluctuating (discharge) pressure it could well be cavitation. Cavitation can in your case be a result of increased flow rate, which could be the result of reduced PRV pressure setting (which will increase flow rate) OR if the PRV pressure is set too high, there will be no flow, the fuel in the pump warms up quickly, and this will result in the same cavitation. Make sure the tank is more than half-full, pump is cold, start and measure discharge pressure. Reduce or increase PRV setting until the pressure is 105-110 psi. If this adjustment takes longer than say 2 mins, switch off the pump inbetween adjustments to avoid heating the fuel, which will accellerate cavitation. Is your suction filter ok (not part-fouled)? The discharge side filter does not influence cavitation, unless fully plugged. Waldi Quote Link to post Share on other sites
Mark Ogram Posted September 20, 2019 Author Report Share Posted September 20, 2019 Photo attached of the PRV plumbing, is it right ? Both the pre filter and post filter are new. The pump is getting hot. Tank is 1/4 full. Thanks. Mark. Quote Link to post Share on other sites
TR NIALL Posted September 20, 2019 Report Share Posted September 20, 2019 1 hour ago, Mark Ogram said: Photo attached of the PRV plumbing, is it right ? Both the pre filter and post filter are new. The pump is getting hot. Tank is 1/4 full. Thanks. Mark. Very hard to make anything from that Photo can you stand back a bit and include the Pump,Cheers. Quote Link to post Share on other sites
Mark Ogram Posted September 21, 2019 Author Report Share Posted September 21, 2019 Another photo. Quote Link to post Share on other sites
TR NIALL Posted September 21, 2019 Report Share Posted September 21, 2019 (edited) 46 minutes ago, Mark Ogram said: Another photo. Hi Mark did you get the Emails? why have you 2 Earths running to Pump or are they both Earths? Edited September 21, 2019 by TR NIALL Quote Link to post Share on other sites
Mike C Posted September 21, 2019 Report Share Posted September 21, 2019 No blockages or kinks in the return line from the PRV to the tank? Quote Link to post Share on other sites
Mark Ogram Posted September 21, 2019 Author Report Share Posted September 21, 2019 4 hours ago, TR NIALL said: Hi Mark did you get the Emails? why have you 2 Earths running to Pump or are they both Earths? Hi Niall, one is in the loom, the other is from the pump to the rear wheel arch. Quote Link to post Share on other sites
Mark Ogram Posted September 21, 2019 Author Report Share Posted September 21, 2019 Think I may have found the problem. I disconnected the return hose that runs from the PRV to the top of the fuel tank I attached another hose to the pipe on top of the tank and tried to blow down it, no joy. I removed the metal pipe and union from the top of the tank and could blow through it. From what I can make out, inside the tank, there is a tube that runs rearly to the bottom. I must have a blockage in that pipe. Has anyone ever come across this before ? Cheers. Mark. Quote Link to post Share on other sites
Waldi Posted September 21, 2019 Report Share Posted September 21, 2019 Good you found it. My return was ok. Waldi Quote Link to post Share on other sites
roy53 Posted August 31, 2024 Report Share Posted August 31, 2024 (edited) Mark are you saying that if you remove the return pipe from the PRV and try to blow through it's no go ? This should be un restricted and free flowing ,so yes you have found a problem. I would remove the tank and clear the pipe in the tank then remove whatever was causing the blockage as you don't want it getting into the pi system. Roy sorry just noticed the date Roy Edited September 1, 2024 by roy53 add Quote Link to post Share on other sites
John L Posted August 31, 2024 Report Share Posted August 31, 2024 I can see an arrow on the top of the diaphragm unit, pointing into the unit, shouldn't this be the fuel in connection? John Quote Link to post Share on other sites
TR NIALL Posted September 1, 2024 Report Share Posted September 1, 2024 9 hours ago, John L said: I can see an arrow on the top of the diaphragm unit, pointing into the unit, shouldn't this be the fuel in connection? John Hi John I think he has it connected the proper way. Quote Link to post Share on other sites
roy53 Posted September 1, 2024 Report Share Posted September 1, 2024 Seems to be something between the brass t piece and the PRV . Looks like the old PRV ? Quote Link to post Share on other sites
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