mph Posted March 30 Share Posted March 30 Hello folks, Twice now I've had my R400 Duratec cut out — completely dead — under hard acceleration. Pretty much the same scenario both times. Warmed up, headlights on, full throttle, and it dies instantly. 10A fuse, fourth up from the bottom, blows. I'm not sure what this fuse covers, apart from almost everything 😂 Interestingly, the immobiliser light flashes happily away to itself once I've stopped and the rest of the car is dead. I've no doubt every single fuse box is different, but on the off chance they're not (ho ho ho), here's a pic of mine — as mentioned, it's the fourth fuse up from the bottom. Given the intermittency of this, where do I even start to work out what could be causing the problem? 😬 All ideas and thoughts most graciously welcomed! Many thanks! --Mark Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted March 30 Member Share Posted March 30 I have the most common layouts of fuses and layouts for Duratecs and the factory wiring diagrams. Please send me a Private Message with your email address. Jonathan 2 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted March 30 Member Share Posted March 30 Do either of these match your Seven? Jonathan 1 Link to comment Share on other sites More sharing options...
mph Posted March 30 Author Share Posted March 30 Hmm. If I took the right hand side of figure 28 and rotated it 180º, then it would fit my fuse box and would be 'D', which would be the fuel pump. And a 15A fuse. Where I currently have a 10A, that's blown twice. Under full throttle… This is looking like a duck, walking like a duck, and quacking like a duck. This may be the ticket @Jonathan Kay — thanks for digging that out. I'll have to pull some fuses and see if that hypothesis stacks up. Thanks for the diagrams! --M Link to comment Share on other sites More sharing options...
BigCol Posted March 30 Share Posted March 30 28 minutes ago, mph said: This is looking like a duck, walking like a duck, and quacking like a duck. 🤔 🦆 🤷🏻♂️ Link to comment Share on other sites More sharing options...
pgm Posted March 30 Share Posted March 30 If you are sure it's the fuel pump fuse you should fit the correct amperage. I have seen similar Ford pumps in other applications, usually Fiestas blow the correct fuse when the pumps become tired and draw excessive current. Link to comment Share on other sites More sharing options...
mph Posted March 30 Author Share Posted March 30 12 minutes ago, pgm said: If you are sure it's the fuel pump fuse you should fit the correct amperage. I have seen similar Ford pumps in other applications, usually Fiestas blow the correct fuse when the pumps become tired and draw excessive current. The next thing to do is work out if it really is that fuse — and yes, if it is, fitting the correct fuse would be a good start 😃 How does a fuel pump become 'tired'? Less effective at delivering what's being asked of it? Link to comment Share on other sites More sharing options...
mph Posted March 30 Author Share Posted March 30 2 hours ago, Jonathan Kay said: Do either of these match your Seven? Jonathan Anyone know what 'D.C.M' is? (fuse O in the diagram) Link to comment Share on other sites More sharing options...
mph Posted March 31 Author Share Posted March 31 Update. It wasn't the fuel pump fuse, and that has the correct rating in. All fuses are correct ratings. Just took me a while to marry up the diagrams in the manual to the actual fuse box 😂 The blowing fuse is O - "flasher unit/D.C.M" I did find a severed earth wire on my left cycle wing repeater, which I fixed. Dunno if that would affect things 🤔 On both occasions it's blown, I had the indicator on, and full beans. Hmm. This is gonna be a right pain to find the cause of, I bet. 1 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted April 1 Member Share Posted April 1 13 hours ago, mph said: The blowing fuse is O - "flasher unit/D.C.M" I did find a severed earth wire on my left cycle wing repeater, which I fixed. Dunno if that would affect things On both occasions it's blown, I had the indicator on, and full beans. Hmm. This is gonna be a right pain to find the cause of, I bet. I'd include relevant relays and the indicator timer/relay in the possibilities. Start by pulling them and looking for evidence of overheating on the relay and the base. Jonathan 1 Link to comment Share on other sites More sharing options...
mph Posted April 2 Author Share Posted April 2 Spent six hours in the car today (to NHM and back) — the fuse blew twice on the M1 on the way down 😬 Slightly hairy coast across a couple of lanes to get to the hard shoulder. I put a 15 in the third time, and that lasted the rest of the day, including the dyno session. Both blows on the motorway were simply when cruising along. I have a 'Superlight' dashboard, with the silver toggle switches. Is the 'DCM' anything to do with those does any one know? If I stick a meter across that fuse, can I monitor load there? Electrical numpty* asking, apologies if question sounds daft 😂 Thanks folks! * be gentle Link to comment Share on other sites More sharing options...
SM25T Posted April 2 Share Posted April 2 To measure current, the meter has to be in the series circuit, not in parallel. 1 Link to comment Share on other sites More sharing options...
22daz Posted April 4 Share Posted April 4 Hi Mark, Not sure if this helps but have a quick check inside your number plate bulb holder. One of the wires on my car came loose and blew a fuse when in contact with the casing. It didn’t cut out, from memory the instruments didn’t light up and it wouldn’t start. I figured if you had the same thing it could trigger the immobiliser when it moved under acceleration and then earthed. However, I’m an electrical numpty so take what I say here with a pinch of salt.. But worthy of a look surely! 22daz 1 Link to comment Share on other sites More sharing options...
Miker7 Posted April 4 Share Posted April 4 You can get resettable fuses - this isn't a permanent solution but it may make it easier to get going again. I've no idea if these will fit in the caterham fuse box. eg https://www.amazon.co.uk/Mintice-Circuit-Automotive-Resettable-Protection/dp/B07HNV4DYC/ref=sr_1_3?dib=eyJ2IjoiMSJ9.bnU5Nb1N6U3l7fVhWaWofc3YHBbYKnmYckyligp-a1_DNqUicTOmAkoMTjd9DPvScvIjHGD9a04r24lODZCK2kqrGTUnyYBwP3qlBiqO_7KT6pfNtbIBkENPDhFDXDQdqiJ4jPX_4Y7s-4cZN0ioePKUn6ymIAS4-e69Dx1SHzRGZJfNB1u3ndk3jvk74OlIHlw1wAcH8Mc54A_6cck-iPU5zk7DebtPnTpfjHAlJ94.RfBcpB8Du1eoyTQPcG06P-IiaRWeJALz1dlLQN37Lyo&dib_tag=se&keywords=resettable%2Bfuse&qid=1712234403&sr=8-3&th=1 As an idea, could you extend out the fuse with a couple of long wires. Then between the wires fit in series an ammeter to measure what current its drawing normally & then tell it to do peek hold followed by a fuse and then wired back into the fuse box. That would ensure you could figure out what size fuse you're requiring and hopefully help identify what is going on as well as still protect the car with the fuse. 1 Link to comment Share on other sites More sharing options...
mph Posted April 4 Author Share Posted April 4 Nice one @Miker7, thank you. The ammeter in series is the sort of idea I was thinking of. I’d like to be able to “debug” the issue 😊 Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted April 4 Share Posted April 4 29 minutes ago, mph said: Nice one @Miker7, thank you. The ammeter in series is the sort of idea I was thinking of. I’d like to be able to “debug” the issue 😊 Most digital multimeters have a current limit of 10A and an internal fuse that will blow over that value, though, so the meter has to be chosen carefully when it is connected inline with the load. 1 Link to comment Share on other sites More sharing options...
mph Posted April 4 Author Share Posted April 4 Good to note @aerobod - near CYYC, thank you. Link to comment Share on other sites More sharing options...
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