Project EXI

The building of a Marlin 5EXi kit car, using a Seat Leon 1.8T 20v Donor
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< 16:41:34 >

Sun Jul 17 16:41:34 BST 2011

Fuel pump fuse

Today I took the time to investigate why the fuel pump fuse kept blowing. I had a 25A fuse in the main board, but it kept blowing. Obviously there was a wiring problem or the fuse rating was very low.
From this line (Brown 11) I have the front fuel pump, rear high pressue fuel pump and power for some of the engine components, like lambda, injectors. This was obviously too much for the circuit to handle.
The highest device on this circuit was going to be the high pressure fuel pump. So I removed the wiring for this and connected directly to the battery with an inline fuse. It blew a 20A fuse immediatly, but did not blow a 25A fuse. So i needed to provide a relief relay for the high pressure fuel pump.
What this means is using the original feed line for the fuel pump to activate a relay so his will switch in another supply line.
Given the high rating of this line I elected to use 4mm cable (I only had red left) so I marked the ground return by slipping some heatshrink over the ends.
Connected some crimp eyelets to connect to the fuel pump, and some a larger eyelet to connect directly to the battery ground. The battery fuse plate had spare blade fuse holders to used one of these and solder the power end onto the battery fuse plate.
Stuck a 30A 12V switch relay, to the rear bulk head, with cable tie base, and connected the relay switch live (original brown 11 fuel pump supply) to the relay. Now when power is applied to brown 11, the realy can switch and provide a separate power supply for the high pressure fuel pump.
I also reduced the fuse panel fuel pump fuse down to 15A, but maybe a 10A fuse will be enough for the circuit, will experiment and see what I can get away with

During the week I also managed to finish the gear gaiter, using the orignal donor leather gear gaiter, I cut a small square panel, stuck carpet onto it, shaped it to fit over the gear stick, and fixed the gear gaiter to it, with M5 nuts and bolts. The plate is held in with M8 bolts that secure the gear tick mount to the car. Looks good and does the job really well.


Posted by Steve | Permanent link | File under: powertrain, electrical