JP Posted March 12, 2022 Author Share Posted March 12, 2022 And I've got continuity from the male side of the grey plug to the YG cable going in to the larger plug on the MFRU. Any tips for opening the MFRU? Link to comment Share on other sites More sharing options...
Dannyboy Posted March 12, 2022 Share Posted March 12, 2022 Do a search. But basically use a Stanley knife around the edge of the cheese block and the mounting face to break the seal. Link to comment Share on other sites More sharing options...
Dannyboy Posted March 12, 2022 Share Posted March 12, 2022 I seal mine back up with silicon after so it's always easy to pull back apart. Link to comment Share on other sites More sharing options...
JP Posted March 12, 2022 Author Share Posted March 12, 2022 So, I've opened the MFRU and the inside looks in good shape. When I turn the key, a click happens and the relay that would be bottom right on the MFRU if the plugs are at the top, closes.Stll no fuel pump sound...still no volts at the inertia switch terminals... Link to comment Share on other sites More sharing options...
Dannyboy Posted March 12, 2022 Share Posted March 12, 2022 So, you need to use a multimeter to check continuity of the wire starting at the MRF`u and working back. have you tried to power up the pump yet using a 12v supply? Link to comment Share on other sites More sharing options...
JP Posted March 12, 2022 Author Share Posted March 12, 2022 OK. So am I right in thinking that the connectors at the small plug to the MFRU activate the relays and those at the larger plug carry the current to power the fuel pump etc? So looking at the mycaterham pic, it seems that the relay for the fuel pump is not closing - it's the one for the main loom that is closing when turning on the ignition...As for powering a 12v supply to the pump, (1) is it fine to take a wire from the battery +ve to the pump wiring and (2) where is the easiest access to wire into the pump ? Link to comment Share on other sites More sharing options...
JP Posted March 12, 2022 Author Share Posted March 12, 2022 I think it may be the pump. So, watching the MFRU relays during start up:Key on, main relay activates and fuel pump relay does momentarily and then opens - presumably priming?On the starter buttonm pump relay closes again during whilt button depressed.Watching a mulltimeter during the same sequence - 11v or so at the pump fuse during "primi8ng", then a drop to zero when the relay open, then volt again hile turning on the starter button. Time to check the pump. I it easiest to remove the rear right wheel for access? is there a plug there? Link to comment Share on other sites More sharing options...
Dannyboy Posted March 12, 2022 Share Posted March 12, 2022 There's a plug behind the right rear wheel, follow the lead out of the pump and you'll find it. Link to comment Share on other sites More sharing options...
JP Posted March 12, 2022 Author Share Posted March 12, 2022 Cheers. I think that may be a job for tomorrow. Rugby now. Link to comment Share on other sites More sharing options...
JP Posted March 13, 2022 Author Share Posted March 13, 2022 OK, I've found the plug at the rear for the fuel pump. I've got continuity from the fuse to the +ve terminal on the plug. I've also got continuity across the pump side of the plug suggesting that there isn't an electrical. problem within the pump.When I touch a 12V feed to the pump plug (taking an earth from other terminal on the plug to the battery) all I get is a momentarily faint clonk sound as if it's coming from the tank / pump.Does this sound like a seized pump? If so, any suggestions for sources of a replacement. There's nothing on the caterham site. Are these still available? Should I look for a motor sport "upgrade" version?Thanks for all your helpJames Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted March 13, 2022 Member Share Posted March 13, 2022 That doesn't sound like a healthy pump. But did you disconnect the existing feed before testing with the new jump feed and for continuity across the pump?Please can you expose the pump/ sender unit and post a photo.My first source for a new pump would be Redline. And Chris probably knows if more than one type was used on your model: sales@redlinecomponents.co.uk.Jonathan Link to comment Share on other sites More sharing options...
JP Posted March 13, 2022 Author Share Posted March 13, 2022 Thanks, Jonathan. Will do shortly. I think I'm going to have to remove the tank to show you the pump. It seems to be in the tank on the right hand side? Unless I'm looking at the wrong thing? Yes - I did disconnect. I unplugged the pump and jumped using the terminals in the plug to the pump and created a new earth. Link to comment Share on other sites More sharing options...
JP Posted March 13, 2022 Author Share Posted March 13, 2022 Here are some pics. The first 2 are of the fuel pump plug. The +ve terminal was quite corroded. Then there is a pic looking up at the tank from below on the right side of the car and a pic looking in from the right wheel arch (for some reason, this has uploaded upside down?). Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted March 13, 2022 Member Share Posted March 13, 2022 Why the image rotation happens and how to avoid it.But am I still 90° out?Jonathan Link to comment Share on other sites More sharing options...
JP Posted March 13, 2022 Author Share Posted March 13, 2022 No Jonathan, the rotation is correct. Camera held in the wheel arch looking backwards. Looking at the right hand side of the fuel tank. The silver on the left is the body skin and the blurry thing on the right is the vertical connector for my rear anti-roll bar.I'm assuming that the pump is under the round disc screwed onto the side of the tank? Link to comment Share on other sites More sharing options...
SM25T Posted March 13, 2022 Share Posted March 13, 2022 Yes it is. You might want to consider replacing that mounting flange with a new plate having a pick up tube welded to it, then fit an inline inlet filter before a new external inline pump, then connect to existing outlet filter. Makes it easier in future with it all external. Mount pump and filters on rear of bulkhead next to original filter. Link to comment Share on other sites More sharing options...
JP Posted March 13, 2022 Author Share Posted March 13, 2022 That sounds like a plan. As you have spotted, the rear basket is in a rough way and my current plan is to strip the car completely and send back to Arch for a blast and re-powder coat or POR15 or whatever is best for longevity. I would like the car running before I start the process so that I know what needs to be replaced and what does not before I start... Link to comment Share on other sites More sharing options...
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