Support Team Shaun_E Posted February 24, 2014 Support Team Share Posted February 24, 2014 I've done further investigation on my earlier problem (http://www.blatchat.com/t.asp?id=235863). The problem now manifests itself as the car cutting out at idle. I've fitted a fuel pressure gauge (in the return before the fuel pressure regulator) and just before the car stalls, the fuel pressure drops to zero having been rock solid at just over 3 bar. It's been suggested that the MFRU is possibly the culprit but I put a meter on the output to the fuel pump (green and yellow wire) and the voltage is constant even when the fuel pressure drops (using digital volt meter so no damping). Inertia switch has a bypass switch which is activated so it can't be the inertia switch. I'm losing the plot on this one so any suggestions gratefully received. Items left to check are fuel filter (being replaced now), fuel pump itself and wiring to fuel pump. Edited by - Shaun_E on 24 Feb 2014 09:08:25 Link to comment Share on other sites More sharing options...
Mark Durrant Posted February 24, 2014 Share Posted February 24, 2014 Shaun How old is the fuel pressure regulator as the sudden drop to zero would suggest this could be the culprit. Link to comment Share on other sites More sharing options...
Rob Walker Posted February 24, 2014 Share Posted February 24, 2014 Sounds like the fuel pump is duff to me. Disconnect the fuel return line and direct into a bucket check if fuel is being pumped when the pressure drops, the reg cannot stop fuel flow. Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted February 24, 2014 Author Support Team Share Posted February 24, 2014 Hi Mark - It was brand new last year. It's a Webcon adjustable FPR. It is possibly the problem but I'm not sure how the pressure can go to zero as it's on the return from the fuel rail. The FPR works in a range so even at the bottom of the range I think there would still be some pressure. I'll have to see if I can borrow one. Just to add - the car restarts immediately with no problem Shaun Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted February 24, 2014 Author Support Team Share Posted February 24, 2014 Hi Rob - I'll try that. Thanks. Link to comment Share on other sites More sharing options...
TJG Posted February 24, 2014 Share Posted February 24, 2014 If it has battery voltage and earth at the pump when it loses pressure it must be a fault with the pump. Tony Link to comment Share on other sites More sharing options...
Jason Plato Posted February 24, 2014 Share Posted February 24, 2014 or maybe the in tank connections rather than the pump itself, I thought the whole pump / cradle assembly looked a bit fragile . Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted February 24, 2014 Author Support Team Share Posted February 24, 2014 Some good ideas here - thanks. I'll drain the tank then remove and check the pump. Link to comment Share on other sites More sharing options...
elie boone Posted February 25, 2014 Share Posted February 25, 2014 This could be a long shot but once i had a volvo 460 😳 that would cut out random and i only found the problem as it refused to fire up. The fuel pump inside the tank had a faulty wire, they feed the wire trough the hole of the male connector and the solder let go. So long the wire was trough the hole in the connector it would only break the connection randomly for a few seconds, when the wire broke loose i took the fuel pump out and found the problem. Resolder the wire and everything was fine. Link to comment Share on other sites More sharing options...
Jason Plato Posted February 25, 2014 Share Posted February 25, 2014 another remote chance that I experienced was the wire that connects to the inertia switch was heating up, this was due to the Mfru having carbon build up on the relay. take the Mfru plug off the Mfru and look to see if the insides are melted ! Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted February 25, 2014 Author Support Team Share Posted February 25, 2014 More stuff to check is good. Thanks. Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted March 1, 2014 Author Support Team Share Posted March 1, 2014 MFRU replaced but problem still there. No melted bits. Tank and pump out and nothing obviously wrong with the pump. I drained the tank using the pump and it didn't stop once ☹️ No loose connections. I think a new pump is the next step. Link to comment Share on other sites More sharing options...
TJG Posted March 1, 2014 Share Posted March 1, 2014 Intermittent problems are a PITA, hope you get it sorted soon. Tony Link to comment Share on other sites More sharing options...
Area Representative Paul Richards Posted March 1, 2014 Area Representative Share Posted March 1, 2014 Shaun I've heard of a problem with a leaf or similar floating in a tank and gradually getting sucked down the tank until it blocked the outlet. Once the pump stopped the leaf floated up and normal service was resumed. Suggest you give the tank a thorough rinse whilst you have it out. Link to comment Share on other sites More sharing options...
Rob Walker Posted March 1, 2014 Share Posted March 1, 2014 If you open the tank filler cap does air rush in , is there a vacuum? If so check the tank breather one way valve could be stuck closed. Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted March 3, 2014 Author Support Team Share Posted March 3, 2014 I removed the pump at the weekend and there was nothing obvious wrong with it - all connections seemed well attached, the filter looked OK, etc. I didn't notice a rush of air on opening the filler cap (and no valve anyway, just a breather tube). I reassembled everything and now it runs perfectly . Always the way! The only foreign object I found was the tip of a biro which was lost in the tank when said biro was used to open the sprung flap when filling with fuel. I suppose it is remotely possible that was shorting out the pump connections but seems unlikely. So I'm no closer to understanding the cause but for now the problem seems to have gone. I think I will order a spare fuel pump in case that was the culprit. Thanks for all the suggestions. Link to comment Share on other sites More sharing options...
elie boone Posted March 3, 2014 Share Posted March 3, 2014 could it have been the electrical connection to the fuel pump ? now everything is back together you have good contact now Link to comment Share on other sites More sharing options...
Mankee Posted March 3, 2014 Share Posted March 3, 2014 Quoting elie boone: could it have been the electrical connection to the fuel pump ? now everything is back together you have good contact now This is quite likely! The other half's Clio dCi came back from a timing belt change/remap on Friday and then wouldn't start at all when hot. Turns out that the solitude sensor (high-pressure pump position sensor) that was unplugged wasn't plugged back in properly. So I unplugged it, cleaned the connections, plugged it back in and now spot-on again, touch wood. But it is French though... Link to comment Share on other sites More sharing options...
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