Hi there folks, Recently bought a new to me '79 308 GTS, on my first drive after the purchase it broke down. I've noted the fuel pump blown, popped in another fuse of identical strength again, and its instantly blown when the ignition has been started. My question is, what else is wired into the same connection as the fuel pump (fuse 3) that could possibly be causing issues on this. Or is it that the pump itself is seized with lack of use/debris from the fuel tank. The fuel pump in question is under the LH fuel tank, Facet, and as far as I can see mounted correctly and using original wiring. If this is a relatively common experience I'd be interested to hear.
Nothing else (in stock form) -- see the schematic at the back of your OM. If you have more than one wire connected at the bottom of fuse #3 someone has added something (and that would be a poor place to add something IMO). Not common, but not unheard of (and there should be a radio-noise suppression capacitor there so that could be shorted). The stock fuel pump is a rotary vane Corona brand -- if you have a diaphragm solenoid Facet, it's been replaced before.
Sounds like it could be a fuel pump issue. Disconnect the wiring at the pump and test it using an outside 12v source and ground it really well. Do not ground the fuel pump to the engine block, make sure the ground on the chassis is very clean. If the pump works with outside wiring then at least you've ruled that out. If not then replace it.
Yeah so it seems it's been replaced before, good info here where would the capacitor be or are they removed when facets are fitted?
So interestingly the fuse didn't pop with 1hr of idling, I them drove it, fuse popped again within 1mi. I then used my power probe on the wiring feed to the pump from the fuse box and it worked just fine I could hear the pump ticking away pulling only .36A. I then refitted a 3A fuse and it hasn't blown in 5mi. It's all unusual.
This is true, I was just putting a small one in as a tester to "sacrifice" before putting in the only 8A I had left.
This post: https://www.ferrarichat.com/forum/posts/148454318/ shows a typical capacitor used for this function (although their body forms vary) -- it has a metal ground mounting tab connected to the chassis (which is one terminal of the capacitor) and a single wire (the other terminal of the capacitor) that connects to the "+" wire of the fuel pump. No idea if the Facet needs one nor if the stock cap would be the best capacitance for the Facet.
