Fuel Starvation Fix - Siphon Pump Kit?

[aeronaut]

I have every part I've taken off the car (that wasn't destroyed in the removal process) sitting on a shelf because I am convinced I am gonna need it again one day...

HA, yea, I know that approach. I un-burried my stack of parts this last spring.
I put a few things on craigslist for 30 days, and zero bites.
Off to the dump it went.

[jayjaya29]

Just ordered this kit last night as part of BW's Labor Day rebate sale. With a few extra G's on tap my car will now begin starving at slightly over 1/2 tank. Happened on the last lap of a race this past weekend.

Question for the group: My current fuel pump seems to be working fine. Any reason not to leave it in place and save one of the two new pumps as a backup? My car is a '99 and the pump is original as far as I know.

Your current pump will not work with the BW dual kit. The stock pump doesn't have an inlet port (its blocked off in the plastic housing).

[fbirch]

Your current pump will not work with the BW dual kit. The stock pump doesn't have an inlet port (its blocked off in the plastic housing).

That makes it an easy decision! Kit is supposed to arrive tomorrow. Can't wait to get it installed.

- - - Updated - - -

BTW, how does the stock system suck fuel from the driver's (non-pump) side of the saddle tank?

[BlackHawkRacing]

BTW, how does the stock system suck fuel from the driver's (non-pump) side of the saddle tank?

There is a hose that relies on a Venturi to pull fuel over.

[fbirch]

OK, so I guess that gets eliminated in the BW kit, since the 2nd pump in the BW kit pushes fuel to the other side directly

[ScotcH]

OK, so I guess that gets eliminated in the BW kit, since the 2nd pump in the BW kit pushes fuel to the other side directly

yes. The plumbing is basically each pump feeding the engine, and the return goes to each pump. Unless they changed it to be serial, in which case the second pump just pushes to the primary pump. Used to be T, not sure if it's been revised. In either case, no need for the transfer hose/mechanism.

[BlackHawkRacing]

yes. The plumbing is basically each pump feeding the engine, and the return goes to each pump. Unless they changed it to be serial, in which case the second pump just pushes to the primary pump. Used to be T, not sure if it's been revised. In either case, no need for the transfer hose/mechanism.

Pretty sure they changed it so that the secondary pump is only feeding the primary.

[golgo13]

For anyone still using the float arm for the fuel gauge, the orientation of the driver side fuel pump housing as called out in the instructions is key to ensuring it reads correctly.

Just want to call that out

[fbirch]

Just got back from installing the BW dual pump kit. Very straightforward. 2nd pump on driver's side feeds a return port on the primary pump on the passenger's side. The primary pump alone feeds the engine.

The post above is correct - you need to orient the 2nd pump on the passenger's side just as called out in the instructions to get the pump to even seat properly. Fuel reading with 7/8 tank is spot on. Will see how the accuracy fares as the level drops.

[fbirch]

Given that most roadcourses are CW, it would have been better had BMW put the pump on the driver's side. It would be possible to reconfigure the dual pump kit to reverse the role of primary and secondary pumps. But the hose that feeds the engine terminates on the passenger side and the fuel return hose terminates on the driver's side. You'd have to add hose couplers and extend each of these two lines over the top of the fuel tank to have the driver side pump feeding the fuel rail and the passenger side pump receiving the fuel return. On my '99, there is a yellow box on the floor of the tank on the passenger side that surrounds the pump pick up and acts as a baffle. No such baffle on the other side.

Probably not worth the trouble if this setup lets you get down to 1/4 tank or less as-is.

[5mall5nail5]

Yeah, the issue is the 13mm and 8mm adapters. You can find some 1/2" and 5/16" but when I looked it ended up being bunch of joints to get the right T and adapters made. Certainly possible, but the BW kit cost is mainly the pump anyway ... the hoses and fittings are pretty cheap part of the kit.

Agree.

I am working on a conversion for my E30 24v (street car) setup. Have an early model w/ in-tank lift pump out to a frame mounted pressure pump. Both pumps are dead after so many years. So putting a Walbro 255 LPH in but had issues going from 8mm to 12mm and back and forth and fuel pressure related and not, etc.

I ended up machining some fittings and welding in for 5/16" in-tank and on the outlet side as well, 5/16" all the way through. My tank has the hose thing coupling the drivers and passenger side, but I don't see tracking the car so single pump is more than likely fine for me.

[fbirch]

Did a couple test sessions yesterday with the BW kit installed and ran it down to 3/8 of a tank with nary a sputter. Ran out of time to run it any lower than that to see where it starts starving. 1/2 tank was the best I could do before,.

[aeronaut]

It works well enough that you'll have to watch your fuel gauge.

[E39SD]

Finally getting around to my BW kit that has been sitting in the box for years. The standard approach on the driver side pump is to rotate the assembly 90 deg. to get the float to clear. But the old Pumpkin approach was to rotate the float by 90 deg so the assembly didn't need rotating. Is there a preferable approach to the driver side install?

Thanks.