John Bracher Posted June 30, 2017 Report Share Posted June 30, 2017 Gents I will be doing some 'fettling' shortly to investigate/possibly install a fuel cooler radiator (Thanks Andreas!!) While the fuel system is apart, I am also thinking of fitting a Non return valve in the line, to help with 'quicker' starting if/when the car is static for a while, due to having to prime all the lines/MU/injector lines/injectors?? My thinking was just upstream from the pump (Bosch)??? Any thoughts/suggestions on location/type of valve?? I saw some nice ones online at one of the 'recommended' High spec pump suppliers, unless you have better experience/suggestions?? Thanks!! John Quote Link to post Share on other sites
HSM Posted June 30, 2017 Report Share Posted June 30, 2017 Bosch pumps are available with none return valves on the outlet side but require a banjo fitting. Harvey S.Maitland Quote Link to post Share on other sites
Waldi Posted June 30, 2017 Report Share Posted June 30, 2017 John, The pump-outlet would be my choise too. I am planning an NRV so will follow this topic with great interest. Waldi Quote Link to post Share on other sites
astontr6 Posted July 1, 2017 Report Share Posted July 1, 2017 Bosch pumps are available with none return valves on the outlet side but require a banjo fitting. Harvey S.Maitland Speedflow here in the UK also sell Bosch non return valves that do not require a banjo, has a male metric thread on one and a AN on the other, so you can do a retro fit if required. Bruce. Quote Link to post Share on other sites
Peter Cobbold Posted July 1, 2017 Report Share Posted July 1, 2017 Why? Isnt the fuel level in the tank above the MU ? And the MU itself is in effect a NRV, the shuttle wont shuttle if the rotors not rotating. An extra valve is one more thing to go wrong, to have to try to diagnose. Peter Quote Link to post Share on other sites
John Bracher Posted July 1, 2017 Author Report Share Posted July 1, 2017 Hello (Peter) That was my understanding too. However, I definately get 'drain back' from the injectors, despite all 6 and the MU being newly refurbed (a year ago). Or, I have a (some) leakage (air getting in) somewhere?? But I'm bu**ered if I can find anything!!! The extra NRV was an attempt at 'belt and braces' thinking.......! Something like this, with suitable adaptors. (Haha, so, more chances for leaks there too!! ) http://www.glencoeltd.co.uk/sytec-one-way-fuel-valves/sytec-motorsport-one-way-valves/sytec-one-way-valve-with-1-8-nptf-female-connection-blue/ And, I think downstream (outlet) side of the pump probably would be better. (My original thinking was to keep the whole pump to injectors pipework 'charged' with fuel, to give the instant 'hit' of fuel as the pump starts). Quote Link to post Share on other sites
stuart Posted July 1, 2017 Report Share Posted July 1, 2017 You do know to not try starting until the note of the pump changes to indicate the pressure is up dont you? Stuart. Quote Link to post Share on other sites
John Bracher Posted July 1, 2017 Author Report Share Posted July 1, 2017 Hi Stuart! Thanks! Yes, I give it a few moments for the pump to settle to a nice steady 'hum', and once the engine fires, it is 'away' instantly!! This may only be 30-40 seconds. Pressure is good, and whenever I have checked it, looks repeatable. Subsequent starting is pretty much instant! Maybe my impatience to get on the road is just getting the better of me??!! Quote Link to post Share on other sites
Peter Cobbold Posted July 1, 2017 Report Share Posted July 1, 2017 I think its asking a lot of injectors, even new, not to allow fuel vapour to leak to atmosphere over long periods unused. You could try removing them from the manifold and capping them. If that works you know the cause. But its easier to live with the 40 second delay Peter Quote Link to post Share on other sites
TR NIALL Posted July 1, 2017 Report Share Posted July 1, 2017 After a Run remover Injectors and leave overnight on Tissue Paper,look for Staining the next Day=Leaking Injectors. Quote Link to post Share on other sites
Waldi Posted July 1, 2017 Report Share Posted July 1, 2017 Some vendors (like Prestige) also supply an NRV as part of their "bosch type pump kit". Waldi Quote Link to post Share on other sites
Guest ntc Posted July 1, 2017 Report Share Posted July 1, 2017 Should not be fitted. Quote Link to post Share on other sites
John Bracher Posted July 1, 2017 Author Report Share Posted July 1, 2017 Neil Is that the particular item mentioned above, or NRVs in general?? Quote Link to post Share on other sites
Guest ntc Posted July 1, 2017 Report Share Posted July 1, 2017 John All there should be no need for one. Quote Link to post Share on other sites
k_raven_smith Posted July 1, 2017 Report Share Posted July 1, 2017 Check voltage to pump static then when cranking Quote Link to post Share on other sites
GT6M Posted July 1, 2017 Report Share Posted July 1, 2017 John All there should be no need for one. If its got a bosche pump, then the mechanical bosche set ups come wid an accuumulator this held pressure int system, t,avoid pressure drop butt, still nee good if yer injecters dribble, even a wee wee bit owa a week or so. As increased residual pressure meks system pressure drop even faster, if there a dribble been thea, fun oot, M Quote Link to post Share on other sites
88V8 Posted July 1, 2017 Report Share Posted July 1, 2017 My car started from cold in less than one engine rotation, even after standing a week. Can't take any credit for that, it had a full Prestige system fitted by Malcolm in 2007. NRV? Not that I know of. It didn't start on all six, so perhaps some of the injectors leaked, but after it started the others soon chimed in. Ultimately, for quick starting at least some of the injectors have to hold the pressure. Ivor Quote Link to post Share on other sites
Alec Pringle Posted July 1, 2017 Report Share Posted July 1, 2017 As Marcus points out, Bosch pumps adapted for TR application date back to the days of K-Jetronic . . . . . and the Bosch systems relied on the accumulator immediately downstream of the pump to maintain pressure to the injectors for rapid starting. Good principle, and one worth utilising for any PI TR - as I found out back in the 70s. Why the vendors of injection upgrades have never cottoned on to this and offered an accumulator I know not . . . . . maybe it introduces an unprofitable degree of reliability ? Cheers, Alec Quote Link to post Share on other sites
Guest ntc Posted July 2, 2017 Report Share Posted July 2, 2017 Not in early pumps defo the old 996,later yes but will only retain pressure for a short time http://www.bosch-classic.com/en/internet/bosch_classic/produkte/motor_1/kraftstoffspeicher/kraftstoffspeicher.html# Quote Link to post Share on other sites
Don H. Posted July 2, 2017 Report Share Posted July 2, 2017 Speaking of K-Jetronic fuel injection systems, back in the day when I drove those it was pretty common practice (for my Audi and VW cars) to energize the fuel circuit for a moment or two to bring up pressure before engaging the starter. One could hear the relay click and the pump run for a second to pressurize the system, and then the car would start immediately. Quote Link to post Share on other sites
John Bracher Posted July 2, 2017 Author Report Share Posted July 2, 2017 Well, thanks gents. Plenty to investigate....... The accumulator sounds like it should be a standard fitment! That said, got in it today, (not moved in a week) ignition on, count slowly to ten, turned the key and vroooom! Cars!!! Quote Link to post Share on other sites
Guest ntc Posted July 2, 2017 Report Share Posted July 2, 2017 Well, thanks gents. Plenty to investigate....... The accumulator sounds like it should be a standard fitment! That said, got in it today, (not moved in a week) ignition on, count slowly to ten, turned the key and vroooom! Cars!!! I rest my case m lord Quote Link to post Share on other sites
Andy Moltu Posted July 2, 2017 Report Share Posted July 2, 2017 As Marcus points out, Bosch pumps adapted for TR application date back to the days of K-Jetronic . . . . . and the Bosch systems relied on the accumulator immediately downstream of the pump to maintain pressure to the injectors for rapid starting. Good principle, and one worth utilising for any PI TR - as I found out back in the 70s. Why the vendors of injection upgrades have never cottoned on to this and offered an accumulator I know not . . . . . maybe it introduces an unprofitable degree of reliability ? Cheers, Alec[/quote Or maybe an accumulator designed for 70 or 80 psi will be of no benefit on a system running at 100psi. Quote Link to post Share on other sites
TriumphV8 Posted July 3, 2017 Report Share Posted July 3, 2017 I am thinking about a fuel storage, too. Not only for good starting but I found pulsations coming from the fuel pump what means for the EFI that the fuel amount may vary if the valve opens at low pulsation wave or higher point. Do not know what pulsations will do with the PI system. Anyway there must some spring load still at 8 bars. Mine storage does at the 3 bars very well. For a good start I would think about letting the pump work shortly against a very low pressure. It will help to blow the hot fuel out of the pump and cool the system a little bit. If there are bubbles they will be thrown out easier. So the pressure valve must release and let the fuel pass at a lower flow level and engage after a few milliseconds. Mechanical bypass to open by hand might be a solution but I would take care because every change in the fuel system might be a risk to cause a nice fire if a hose pops off. Quote Link to post Share on other sites
Waldi Posted July 3, 2017 Report Share Posted July 3, 2017 Regarding hydraulic accumulators: there are 2 basic principles: A: Energy storage B: Pulsation damping If the spring force (or typically: nitrogen pressure on rhe orher side of a membrane) is low, it will mainly work as energy storage. Quote Link to post Share on other sites
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