Yellowperil Posted May 25, 2012 Report Share Posted May 25, 2012 800 miles under my belt and trying to work out the route of a problem. Any advice / opinions welcome. I have a 150 bhp fuel injected car. If I keep to around 3500 rpm all is well. If I accelerate above that she pulls really well but, when I then change up a gear, she coughs and splutters for the next 500 yards, seems like fuel starvation. My car is set up with 2 fuel pumps in the boot, and I can choose between them with a switch on the centre consol. The problem is present with either pump and worse with one than the other. So, 3 questions really: 1. Any ideas as to the cause of the fuel starvation? 2. Any one come across a set up with selectable pumps before? Seems like someone has gone to quite a lot of effort. 3. Any recommendations around an alternative fuel supply system? I was also interested to read recent thread re fuel smell in boot. I have a strong smell of fuel in the boot, but no signs of a leak. Jeremy Quote Link to post Share on other sites
Guest ntc Posted May 25, 2012 Report Share Posted May 25, 2012 Yes I have seen two pumps,but which ones do you have fitted? Quote Link to post Share on other sites
Jersey Royal Posted May 25, 2012 Report Share Posted May 25, 2012 And how are the two pumps piped? Photo would be useful Cheers Guy Quote Link to post Share on other sites
Denis Posted May 25, 2012 Report Share Posted May 25, 2012 (edited) Errr...3. Fit one Lucas Fuel Pump that was designed for the Lucas Pi system ? Edited May 25, 2012 by Denis Quote Link to post Share on other sites
Guest ntc Posted May 25, 2012 Report Share Posted May 25, 2012 Errr...3. Fit one Lucas Fuel Pump that was designed for the Lucas Pi system ? People wiser than you or me have fitted more than one Lucas pump in line Quote Link to post Share on other sites
Peter Cobbold Posted May 25, 2012 Report Share Posted May 25, 2012 Sounds like the pumps are in parallel - the pump that is off could act as leakage path back to tank, dropping the fuel pressure. Quote Link to post Share on other sites
tr62500 Posted May 25, 2012 Report Share Posted May 25, 2012 W Quote Link to post Share on other sites
tr62500 Posted May 25, 2012 Report Share Posted May 25, 2012 can only suggest the problem is with the metering unit. would be interested to know if there is any difference in the delivery pressures between the two pumps. Can only suggest you are near to a 'cliff ede' around 3500 rpm on fuel delivery. Quote Link to post Share on other sites
Yellowperil Posted May 26, 2012 Author Report Share Posted May 26, 2012 Not 2 pumps but 3 ................. I have drawn a layout of the plumbing, but not sure how clear it is. The fuel comes from the tank , through the facet pump, and on to the filter. It then goes to a T piece where it splits and feeds to both Lucas pumps. It then leaves these pumps and converges at a second T piece and runs through to the engine bay. Only one of the Lucas pumps has a cooling coil. This is fed from an further T piece, just before the fuel pipe leaves the boot, and returns back in to the top of the fuel tank. The fuel filter has the date 3/6/96 written on it. Guess a new one could be a little overdue! Some one seems to have gone to a lot of trouble setting all this up. Jeremy Quote Link to post Share on other sites
Peter Cobbold Posted May 26, 2012 Report Share Posted May 26, 2012 (edited) Jeremy, That might work if both pumps were on together, providing the PRV was capable of carrying the surplus fuel. As I said above with parallel pumps - which is what you have inherited- if one is switched off it could act as a leakage path,limiting the fuel pressure as demand rises. Try clamping shut the hose supplying the pump that's off. Or removing both T pieces. You dont describe a PRV in the circuit after the pumps. Nor what limits the fuel flow through the cooling coil - its not fed at full pressure is it?? I would not assume PO knew what he was doing, despite the trouble taken. Bag of worms- I'd return it to standard. Peter Edited May 26, 2012 by Peter Cobbold Quote Link to post Share on other sites
john.r.davies Posted May 27, 2012 Report Share Posted May 27, 2012 Yp, Multiple pics, but they don't enlarge, and the flow chart is unreadable. Please post another of your flow diagram, in a bigger format. This board only allows you 500Mb of picture (meanies!) so you may need to dlete some old pics to make space. Click on the down arrow next to you name, top line, select "Manage attachments" in the left column, and select pics to delete. I'd first change that filter. I had very similar symptoms when a pre-pump filter was blocked with tank gunge. Then, if no better, get a pressure gauge and see what's happening when the symptoms start. John Quote Link to post Share on other sites
Yellowperil Posted May 27, 2012 Author Report Share Posted May 27, 2012 Thanks for the replys, When I took the pictures I found that the Facet pump was not secured in any way. It dis, however, have some old rubber carpet underlay wedged around it to keep it in place. I have been to work and back today (40 miles) without the underlay in place and she has run almost without a splutter. That leads me to think that either the pump was over heating in it cosy surroundings?, or it wasn't getting a good earth? I will secure it properly and see how she gets on. Still interested as to why some one would go to the trouble of wiring in 3 pumps though. Jeremy Quote Link to post Share on other sites
Yellowperil Posted May 27, 2012 Author Report Share Posted May 27, 2012 ps, Bigger pictures John, it took me around 3 hours to get those ones loaded.................!!!! Quote Link to post Share on other sites
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