<Solved>Re: Does fuel pump prime at key on Bosch M3.3.1 ? - NO

[nomecone]

The original account asking a question has been removed. That is how this reply to a non existing question is here. All posts from OP were removed. OP was bfrqrv

update - bc I am now the first post I can change the topic name... so I did. It now is the actual question. I also corrected the motronic version number from 3.1.1 ( that does not exist) to 3.3.1 as was verified by the OP after some questioning.

Here is the answer:

Color me surprised. NO PRIMING is the correct answer.

Something else is running for ~1 second at key on and clicking off. Multimeter only showed power to pump when cranking. Not on key 1 or 2 positions while car is off. I did not start the car as I had the power disconnected from the pump to easily test the leads. Car does run when plugged back into the pump.

My original first reply asking what the heck 3.1.1 was:

What car do you have with M3.1.1?
-fixed wrong info

[nomecone]

Pump powers on when key is in start position. DME does not regulate it to my knowledge. - Updated with corrected info

The m3.1.1 does not exist to my knowledge either.

dmes_1000004120.png (184.53 KiB) Viewed 2974 times

[nomecone]

Update this was not the pump sounds it was something else. no prime at key on

I have m50tu car. No rear seat. I can hear something come on when key turned to on. Could be set time only.

Pumping is not audible. A relay that turns on is and, ~1sec a click/clunk sound can be heard.

Key on, relay clicks, 1-2 seconds later heard turning off sound click. Did it repeatedly and it did the same sequence everytime.

I have the seat out and pump access cover open. YMMV with assembled car.

[nomecone]

Interesting thx. I was wondering how can this happen with only 2 wires to the pump assembly? What do you mean there are no extra wires needed to show the DME the pressure, I cant understand the technical route what is happening can you explain? The only thing hat is not OEM is the pump itself

I never said the DME sees the fuel pressure. I said if a pressure switch is internal to the pump there would be no extra wires needed.

[Baltica]

As far as I know the pump is turned on by turning the key to the start position. m3.3.1 does not have fuel pumping before starting like in ms40.1

[nomecone]

I'll put multi meter on and check this weekend

[bfrqrv2]

My account was corrupt like it seems and I didn't managed to login anymore. I don't know what happen I didn't changed anything. So I go further with a new account

[bfrqrv2]

I'll put multi meter on and check this weekend

anything?

[nomecone]

Color me surprised. NO PRIMING is the correct answer.

Something else is running for ~1 second at key on and clicking off. Multimeter only showed power to pump when cranking. Not on key 1 or 2 positions while car is off. I did not start the car as I had the power disconnected from the pump to easily test the leads. Car does run when plugged back into the pump.

[nomecone]

As far as I know the pump is turned on by turning the key to the start position. m3.3.1 does not have fuel pumping before starting like in ms40.1

Correct answer. I was mislead from the sounds I was hearing.

[bfrqrv2]

Thanks for this information! The reason I looked for more info is that I not only heard the priming but also saw it when I had a fuel pressure gauge hooked up once and turned the key to position 2. That makes it spooky, because I also believe the M3.3.1 doesn't prime