Is it possible that red and blue terminals on new fuel pump do not mean (+) and (-)??

[baloo]

So I replaced my fuel pump on the 87 3.2L with a Bosch 044. But I have a discrepancy between the new and the old pump terminals!

On the old pump, both terminals have a BLUE plastic indicator glued into the terminals.
However, the two terminal screw sizes are different:
1) The RED wire goes to the SMALLER terminal screw (the casing is stamped (+)),
2) and the BROWN ground wire goes to the LARGER terminal screw (stamped (-),
BUT BOTH TERMINALS ARE BLUE.

HOWEVER, on the new fuel pump (Bosch, made in Czech, 044) the small terminal has a BLUE plastic indicator, and the LARGE terminal has a RED plastic indicator. There is no (+) or (-) stamped on the pump itself. Only these colored plastic washers on the terminals

Logic says that my small gauge RED feeder wire from the car would naturally fit onto the SMALL terminal screw on the new pump (which happens to be BLUE), and the larger BROWN ground wire should go onto the large terminal screw, which is RED.

However, isn't RED traditionally the (+) terminal?
Should I change out the terminal ends of my wires so the small red wire from the car goes to the LARGER RED terminal screw, and the large brown ground goes to the SMALLER BLUE terminal screw on the pump?

Why are the two Bosch pumps different from each other in terms of size?

[NICE 69 S]

See if there is continuity between either terminal and the body of the pump. If there is, that would be the ground terminal.
Bob B

[winders]

Electrical: Positive M6 / Negative M5

[winders]

http://www.bosch-motorsport.com/media/catalog_resources/Fuel_Pump_FP_200_Datasheet_51_en_2776426379pdf.pdf

[Joe Bob]

Digital Volt Meter is your friend.

[winders]

A digital volt meter won't tell you which terminal on a fuel pump is positive and which is negative. Unless, as NICE 69 S pointed out, the metal body of the pump is tied to the ground terminal of the pump.

[Joe Bob]

It will tell which is a ground.....

[Bob Kontak]

Originally Posted by winders

A digital volt meter won't tell you which terminal on a fuel pump is positive and which is negative. Unless, as NICE 69 S pointed out, the metal body of the pump is tied to the ground terminal of the pump.

Just pulled my original 81 fuel pump out and replaced. Thought it was dead but my "fender bender" froze the fuel gauge at 1/3 tank. It was out of gas.

Checked it out with a MM. Both terminals ground to case. Hooked it to a battery and it runs. Changed polarity, it ran backwards.

[Quicksilver]

One detail on the fuel pump on a 3.2. It won't see voltage until the DME sees the engine is spinning. So if you are thinking there is a problem because you turn the key to 'Run' and the pump doesn't start then you need to check it while cranking.
The better/easier idea of testing it is to jumper the DME relay and see if that fires it up. Here is a pic and description: DME Relay - carry the spare.

[baloo]

Originally Posted by NICE 69 S

See if there is continuity between either terminal and the body of the pump. If there is, that would be the ground terminal.
Bob B

BOB, there is no continuity between EITHER of the terminals and the body. When I place both meter probes on the body of the pump, there IS continuity. So body must not be grounded

Originally Posted by winders

Electrical: Positive M6 / Negative M5

WINDERS: on my original pump, the SMALL terminal (M5) is the red/(+) terminal. Hummph.

Originally Posted by winders

A digital volt meter won't tell you which terminal on a fuel pump is positive and which is negative. Unless, as NICE 69 S pointed out, the metal body of the pump is tied to the ground terminal of the pump.

WINDERS: Body must not be grounded.

QUICKSILVER, yah, I have that diagram and a jumper (used it to diagnose the faulty original pump). But thanks for reminding me of the link.

BTW, I held the body of the pump while the wife cranked the engine. The pump was running. Must be running backwards.

I guess I'll put a bigger terminal on the red/small lead and reverse the hookups and see if sumptin happens.

[winders]

Originally Posted by baloo

WINDERS: on my original pump, the SMALL terminal (M5) is the red/(+) terminal. Hummph.

The information I provided was for the Bosch 044 pump. I even included a link to a PDF file. I have no idea what pump brand and part number you had before.

[baloo]

Winders,
Yes, I read the attachment, but i missed the + and - in front of M6 and M5. thanks.

[baloo]

Well, that did it.
BOTTOM LINE: the red (+) power line to the fuel pump on the original 1987 3.2L Carrera has a SMALL terminal eye that fits over a small terminal stud on the original fuel pump. The ground wire is to the LARGE terminal.

When swapping out for an 044 pump, the RED (+) terminal stud on the fuel pump is LARGE terminal and you have to change to a larger eye connector.
The ground on the 044 is the smaller of the two terminals on the pump. Since the eye on the ground wire from the car is large, it will fit over the smaller terminal.
However, since there is such limited working space and wire, I spliced in 6" pigtails to lengthen the leads, and changed the ends to bayonet connectors at the fuel pump.

The end, but NOT. Now I have a leak in the actual steel line going into the fuel filter -- probably rusted out. One problem after another...

[winders]

By the way, if you look on the Bosch 044 fuel pump, cast into the housing by the fuel outlet are "+" and "-" signs. These make it clear which terminal is positive and which is negative....

[baloo]

Originally Posted by winders

By the way, if you look on the Bosch 044 fuel pump, cast into the housing by the fuel outlet are "+" and "-" signs. These make it clear which terminal is positive and which is negative....

Winders..... Nope, no + or - cast into the body like on my original pump. And the mismatch of wire sizes as mentioned above. Only thing is the red and blue plastic markers on the terminals.
Yes, the pump is Bosch, marked 044, and made in Czech.

[winders]

This what my Bosch 044 looks like:



Notice the "+" and "-" signs cast in near the base of the fuel outlet.