Okay I'm sure this has been addressed before, but here I go......My original pump failed so I replaced it with a BOSCH pump and mounting it in the same general area as the original pump. My question is what is the direction of flow? One end is larger than the other. Which on is inlet and which one is the outlet? Thanks in advance

So, no markings or instructions?

The intake is big intake, outlet pressure is the small outlet, as seen on my 928.

I believe the larger end is the inlet. It matches with the larger output end of the square filter placed ahead.

Here is an added question for you though (and absolutely no instructions whatsoever with mine), which is the ground and positive terminal? No marking on mine. Resistance between the case and the larger thread is lower than from the case to the small thread which leads me to believe that the larger one is ground...

Take a look at the plastic end cap, usually it'll have a + and - molded into the plastic around the base of the terminals.



And it's usually annoyingly small and difficult to make out as a terminal marking.

None and nothing in the instructions

Hi, I have the same pump, it just arrived. Same here...no instructions and no markings. There is a 12mm and a 8mm cionnection. I think the 12 mm is the inlet from the fueltank (filter in between) and the 8mm is the side to pump to the engine.

More detail: Most of the time when pump is relocated to the back, the tankoutlet line is 9,5/10 mm.......a fuelline of 9,5/10mm attached to that, an adapter from that size down to 8 mm and then a 8 mm line to the 8 mm inlet of the filter. From the filter out, it 12 mm (I am talking about the square fuelfilter suited for injection systems). 12 mm out the filter to 12 mm inlet of the pump. pump out is 8mm to engine.

edit: I do not have the same pump, I ordered a Bosch 69133, but my info is still valid.

Hook it up. 50/50 your car won't start.
If your car won't start you know you have the pump wired backwards.
Change the wiring and try again. Chances of harming the pump are very small.

Zach

Thank you for the input

After looking closely, I did see the + an - sign where you are showing, next time, I will make sure I wear my glasses
The negative is the larger terminal screw, confirming my resistance measurement.

@VaccaRabite , Since this is part of a Microsquirt installation project, I prefer eliminating that variable up front... Not that anything should go wrong at the first start...

That's the one I've put in numerous cars.
Large end, input.
Small end, output.

You can always use an aftermarket pump...

Airtex External Electric Fuel Pumps E8445

$69.99 from Summit Racing. Available at your FLAPS for about the same.



They are the exact same pressure and volume as the factory fuel pump. We have one on Betty's 914 that has been there for years. It works great.

Airtex External Electric Fuel Pumps E8445