David's Build Thread

[alga]

Originally Posted by Davidbolam

Here is a picture of the earth bond I have added to my tank. I have used 17 amp wire. Will this be sufficiently thick?

More than enough. Fuel pump and sender probably have their own ground feeds, this one is just to prevent static buildup on the tank.

[Davidbolam]

Originally Posted by CTWV50

Hi David,

Just modded the sender for my build to fit it into the tank. My first question is....

How have you bolted/bonded the pump and sender unit to the tank?

and secondly.....

Surely if you earth the tank to the body when fuel causes a path of least resistance between the tank and the live wire in the tank the pump and/or sender will stop working and probably blowing a fuse or worse causing a spark in the tank??

I was thinking about this this morning after reading up on fitting a metal fuel tank. Surely the tank needs to be isolated from the body altogether?

Confused!

To install the send i used m4 ultra low profile rivnuts. I then used the rubber gasket of the sender unit that is quite thick and lots of sealant. Robo recommended some sealant that was made by 3m and resistant to almost everything. The sides of the sender were ground away slightly with an angle grinder so that I could get a flush fit.

As far as the earth goes the sender has its own earth that runs back through the cars electrics however I added another one to satisfy my IVA. The fuel pump still works with the earth attached. I think the tank is negatively earthed on an mx5.

Let me know if you find out otherwise...... (in case I blow my garage up by mistake)

[Stot]

Originally Posted by CTWV50

Surely if you earth the tank to the body when fuel causes a path of least resistance between the tank and the live wire in the tank the pump and/or sender will stop working and probably blow a fuse??

Petrol has very little electrical conductivity. Consider that the fuel level sender is offen a bare resistance coil dipped right in the petrol and it doesnt affect it. Also given that the fuel is wrapped up in metal, the fuel its self will never be the path of least resistance. AFAIK most fuel tanks are earthed.

edit: Found this in a Fire Brigade, Fire Safety leaflet.

Petrol Engined Vehicles
Gasoline vapours contained within the fuel tanks of road vehicles are generally too rich to ignite. However, there is a zone near the tank filler cap, which may be in the flammable range when the cap is removed. During fuelling, flammable atmospheres may exist externally around the filler orifice. Therefore the possibility of an ignition from electrostatic discharge has to be considered.
The flow rates and hose diameters used at service stations are usually small enough to ensure that dangerous levels of static charge are not built up in either the vehicle's fuel tank (provided the design is such that it is not highly insulated from the vehicle body) or on the surface of the filling hose. There is the possibility however that an insulated conductor involved in the operation, such as the filling nozzle, the vehicle itself, an insulated filler neck on the vehicle tank, or the person doing the filling, could accumulate a static charge. Any of these could produce a spark in the flammable zone around the filling inlet and cause an ignition.

Cheers
Stot

[CTWV50]

Thanks for that david. And thanks for clearing up the question of petrol condutivity everyone! Haha.

[flyerncle]

Have seen films of petrol tanker explosion caused through static when I did an ADR course, Guy was blown from top of tanker when answering phone,a women slides across seat to get purse and touches nozzle and bang nice fire.

Moral of story,dont wear nylon and earth the tank.


Sender unit resistor is insulated from body of tank otherwise A,it would not work and B it would short and blow fuse.

[Eternal]

LOL thankd David you are my 200th sub on youtube! Will have to send you a Mars bar or something =P

[Davidbolam]

Originally Posted by Eternal

LOL thankd David you are my 200th sub on youtube! Will have to send you a Mars bar or something =P

I've also noticed a new roadster on there. its only been on for 2 weeks and is racing an m3 around a track. Looks like spuds car.

Does anyone know who's it is??
David

[mark]

Definitely spuds car

Seemed to be doing ok too, although the m3 seemed more interested in going sideways than fast

[flyerncle]

Had a ride in Spuds car at Teeside,well sorted and handy motor,defo better than beemer.

[Davidbolam]

Has anyone got an idea of how I can remove the old pipe from my exhaust. There is a rusty bit of 2 inch tube that has been forced inside the exhaust. .??....

Here is a photo. I have tried wacking it with a BIG hammer and a cold chisel. Now I just have 2 holes. I tried heating it on the cooker to expand it a little but it's stuck fast? Tried wd40 as well