316 carb to 325i

[ricey46]

Right guys,
since my M20 B25 engine is ready now, and the sport isn't, it's going into 316 so it can be ran in and used rather than just sitting about.

This....


into this...



So I need advice on what needs done before fitting, but more so about the fuel pumps.

I've got the old tank with the required sender unit, The main problem I can see is that the 316 doesn't have the two fuel pump set up the the 325 has.
-So will I have to run a supply to the second fuel pump or is the supply standard on all of the early looms, just not used??

I've got new fuel pipes also as the 316 only has a supply pipe, no return. The engine loom will be fine and will plug straight in and all other things should be fine. It's just the fuel pumps that are concerning me??

All info would be great!

Also should I change the diff and put the 3.64LSD into it or just leave the small case 4.10??

Cheers Paul.

[johnl320]

I've done 316 to 335i conversion on the same year 316 as yours.
1. fit the extra fuel pipe

2. fit a 318i in tank fuel pump to your existing tank ( it will fit)

3. find the unused fuel pump connection underneath the rear bench seat, extend them slightly so they will reach the in tank pump.

4. fit a fuse in the correct slot in the fuse box.

thats what i did and it runs fine

john

[Brianmoooore]

As above, but ideally you should replace (with the later type) the small wiring loom that plugs into the socket at the RH end of the rear seat pan, then goes down through a grommet to underneath the rear of the car, and comes back over the top of the tank to the fuel pump and level sender.
Only 325's up to '87 had two fuel pumps - one in the tank, and one in front of the LH rear wheel arch. Later 325's only have one in tank fuel pump, with a second level sender in the LH section of the tank.

[GeoffBob]

Also should I change the diff and put the 3.64LSD into it or just leave the small case 4.10??

Fit the 3.64LSD. Regardless of whether it's a LS or open unit, the lower ratio diff will bring your revs down at motorway speeds, making cruising more comfortable and improving fuel economy. The 3.64:1 ratio diff will, however, reduce your wheel torque compared to the 4.10:1, but this is more than compensated for by the stronger replacement engine.

The fact that it's a LSD is an added bonus.

Tidy two-door BTW. Nice!

[Kedge]

Thank god i just saw this, i hadn't given fueling any consideration at all with doing this same swap.

Is the 318i pump standard on all 318i's? How hard is it to get the fuel line in place, will i need to drop the tank or anything daft like that? Also come some one get a pic of the loom that need adding/changing please.

[Brianmoooore]

All E30 in tank fuel pumps are the same, but the mounting frame for those on the smaller 55 litre tank has a hose connection for the excess fuel returning to the tank. The 62 litre tank has a connection for the returning fuel half way along the tank, so the pump frame for these has the second connection cut and blanked off.

[johnl320]

I've also used the redundant bracket that would hold the pump if the the car was a 325i to hold a fuel filter you will only have a tiny inline filter on the m10.

john

[Kedge]

Had a rummage round today and found this is in the garage;


I assume this is the pump i will need?

[johnl320]

yes

[Kedge]

Right time to dig this thread back from the depths as i'm being a bit dumb with this .

Basically what do i need to do to wire up the pump?

This is the connector that went into the old pump and the white bit is where it plugs into the car loom. Is this what will need to be wired into a new plug to fit on top of the sender unit on the above pump and does the order of the wires matter?


As for the unused pump connection, is that normally found on the passenger side with this type of connector taped up?


Or is the option Brian on about mean i simply have to unplug the white connector, feed it under the car and that'll give me all the correct connections for the pump?

[Kedge]

Got the wiring loom from a facelift car today so got the correct connections for the pump but the plug back to the cars main loom is different so not a simple plug n play i was hoping for.

Can someone please give me an idiots guide please.

[johnl320]

You have Pm