Neil_K Posted May 15, 2010 Share Posted May 15, 2010 Following these instruction here to fit an external relay for the starter, I don't understand how the original relay in the MFU is bypassed? Surely adding another relay will essentially be after the MFU relay, and therefore the poor MFU relay will still be in circuit? Comparing to the instructions on Myles site (originally by Chris W ) the relay is cut out of the MFU and a new one added instead. The first option direct off the battery seems to be the preferred method, but I can't get my head around how it's triggered without getting the same problems ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Calm down dear, it's only a forum! Link to comment Share on other sites More sharing options...
Gingerbread Man Posted May 15, 2010 Share Posted May 15, 2010 Is it not the idea of relocating the relay away from the direct heat of the engine? Link to comment Share on other sites More sharing options...
Tony Whitley Posted May 15, 2010 Share Posted May 15, 2010 Not bypassed, but the MFU relay now only has to operate the new relay which does the heavy work and directly connects the battery to the solenoid. I had the MFU relay bypassed but when that stopped working so well I added another relay which directly connected the battery to the solenoid! It worked for a while but the change that really cured things for me was re-routing the wiring so that everything but the main starter feed goes through the battery cut-off switch. It won't pass scrutineering but I feel it's adequate for a road car. Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted May 15, 2010 Leadership Team Share Posted May 15, 2010 I've done it both ways - old car I by-passed the MFU and t worked great, new car I left the MFU in and added the new relay, and worked equally as well. The MFU is a perfectly reliable piece of kit, it just doesn't like the load/heat in the Caterham install. Reduce the load and it works fine. Stu. Joint Area Representative MAD Sevens (Merseyside And District) www.superse7ens.co.uk..........the rebuild 😬 Link to comment Share on other sites More sharing options...
Neil_K Posted May 15, 2010 Author Share Posted May 15, 2010 Perfect, cheers gents ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Calm down dear, it's only a forum! Link to comment Share on other sites More sharing options...
tweeky Posted May 16, 2010 Share Posted May 16, 2010 what value of fuse should I use if i used a 30Amp realy? I did notice a recent thread on this but carnt seam to find it. Ta in advance Tweeky to infirmity.................... and beyond Link to comment Share on other sites More sharing options...
jradley Posted May 16, 2010 Share Posted May 16, 2010 Sorry to hijack this thread, but having discovered my car suffering from the dreaded click this weekend I am all of a sudden interested in it..... In my case I am pretty sure the starter is engaging but then not powering the motor. Reason being on one occasion it went click, there was a slight pause and then the starter spun the engine over and it started fine. Is adding a relay likely to help in this situation or is it more likely something else ? Cheers, John Link to comment Share on other sites More sharing options...
shn7 Posted May 17, 2010 Share Posted May 17, 2010 John, In a word yes. The "click" and your problem comes from not enough amps getting to the solenoid/starter to turn the engine over. The relay mod will help. Steve. Not forgetting Percy the Polar Bear who recommends Puddle Pet Care Link to comment Share on other sites More sharing options...
Area Representative Paul Richards Posted May 17, 2010 Area Representative Share Posted May 17, 2010 John If the starter is actually engaging, then relay mod may not help. Click is usually when power to actuate the starter solenoid isn't happening and usually happens when engine is hot. Your problem could be dirty contacts and gummed up starter/slenoid. You could try relay mod (less than £10 and 30 mins) as it will do no harm. If not cured suggest stripping and cleaning starter. Paul Richards Area Representative - L.A.D.S. (Lancashire and District Sevens) LADS Website Growing old is compulsory - Growing up is optional Link to comment Share on other sites More sharing options...
jradley Posted May 17, 2010 Share Posted May 17, 2010 Thanks - I will put a relay in and see what happens. I've not had a problem before and have started the car previously on a hot engine, but rarely after it is stood for just a few minutes hot - normally it's straight away after stalling or after it's cooled down. I have now cleaned up the contacts, they were ok but are better now, and also tightened up the top mounting bolt, which was falling out ! Something about the relay mod which is never mentioned - if the relay sticks on then this would be bad, as turning off the ignition wont stop the starter from running. I guess it's rare for a relay to fail in that way but in theory could happen. It's worth the risk if it means I don't get the click though. Off to Maplin :) Cheers, John Link to comment Share on other sites More sharing options...
Neil_K Posted May 18, 2010 Author Share Posted May 18, 2010 Follow the instructions linked to above. Nice and easy. 30 amp fuse in the 30 amp relay, and make sure you use 30 amp wiring too, or that will burn out before the fuse should a short occur ... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Calm down dear, it's only a forum! Link to comment Share on other sites More sharing options...
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