Magneti Marelli

[Sector-9]

Anybody fitted any MM pumps to their diesel? I've bought and fitted the ITP and UBP and am hoping being branded items they might be better quality than the unmarked junk flooding ebay.

[mh007]

Yes, I've fitted a few (ITP & UBP) without any comebacks.

[Heddy]

Haven't fitted MM but keen to know if the UBP is quiet. I've had to change the UBP fitted when I bought the car because it whined. I'm using a used Pierburg at the moment, can't hear it at all

[Mickyboy]

I've not ever fitted one myself, however the proof is in the pudding, and often the only way of really knowing is when it's plugged into a T4 machine measuring fuel pressure I found a lot of aftermarket pumps don't produce correct pressure & only T I automotive which is available from Rimmers and Pierburg if you can get one as Rimmers seem to supply TI automotive pumps, funny enough I had this conversation with Brian a short while ago, before he got a temporary rest period from the forum
Mick

[Sector-9]

Originally Posted by Heddy

Haven't fitted MM but keen to know if the UBP is quiet. I've had to change the UBP fitted when I bought the car because it whined. I'm using a used Pierburg at the moment, can't hear it at all

It's definitely noisier than the Pierburg it replaced. Not that it bothers me as with the engine running it's hardly noticeable, but what worries me (and what happened on the last two no-name pumps from ebay) is that fuel will leak through the multiplug connector and into the wiring loom. If the connector stays dry then I don't care if it's louder in operation or not.

[Sector-9]

Originally Posted by Mickyboy

...often the only way of really knowing is when it's plugged into a T4 machine measuring fuel pressure I found a lot of aftermarket pumps don't produce correct pressure...

You made me paranoid so I went out with TOAF and recorded fuel pressures on the repaired car and the spare one. The spare has a Pierburg pump and recorded approx 3.68bar at idle, the repaired one has a Magneti Marelli pump and recorded approx 3.55 bar at idle. Both are comfortably over that needed for starting, though I suspect the Pierburg pump would cope better at high engine loads (the MM pump pressure dropped to around 3.42bar when the engine was revved in neutral - I didn't test this on the Pierburg). Of course, the difference could be caused by other factors than just the pump as they are two different cars and with different fuel maps.

I did originally try just the new UBP as I didn't relish replacing the ITP again, but it didn't seem able to prime itself so I had to swap the ITP. Also I noticed that if I unplugged the Pierburg UBP wiring whilst the engine was running, it would stop almost immediately. On the MM pump, it seems to idle for several seconds before finally cutting out which makes me wonder if fuel from the ITP is able to flow through it, which might also explain the lower pressure if the pumping element isn't as well sealed as the Pierburg one?

[Sprinter]

I picked up a MM UBP a couple of years ago when mine started to get noisy.

No problems so far and regards MM as a decent brand. (kept the noisy one as an emergency spare)

[ceedy]

Had a marelli under bonnet pump in for about 6 months so far with no problems

C.

[Mickyboy]

Originally Posted by Sector-9

You made me paranoid so I went out with TOAF and recorded fuel pressures on the repaired car and the spare one. The spare has a Pierburg pump and recorded approx 3.68bar at idle, the repaired one has a Magneti Marelli pump and recorded approx 3.55 bar at idle. Both are comfortably over that needed for starting, though I suspect the Pierburg pump would cope better at high engine loads (the MM pump pressure dropped to around 3.42bar when the engine was revved in neutral - I didn't test this on the Pierburg). Of course, the difference could be caused by other factors than just the pump as they are two different cars and with different fuel maps.

I did originally try just the new UBP as I didn't relish replacing the ITP again, but it didn't seem able to prime itself so I had to swap the ITP. Also I noticed that if I unplugged the Pierburg UBP wiring whilst the engine was running, it would stop almost immediately. On the MM pump, it seems to idle for several seconds before finally cutting out which makes me wonder if fuel from the ITP is able to flow through it, which might also explain the lower pressure if the pumping element isn't as well sealed as the Pierburg one?

Hi there mate having looked at the measurements you have got 3.55 bar is fairly low really a good pump like Peterburg or TI automotive should produce over 3.8 to 4 bar

There are other factors to take into consideration like the one-way valve on the pierburg valve located underneath the under bonnet pump, or slight kinkage in the cross pipe in the saddle tank for example

However saying all that 3.55 bar will be okay For everyday running. And at around 3000rpm probably drop to about 3.1 bar

Mick

[FrenchMike]

Originally Posted by Sector-9

You made me paranoid so I went out with TOAF and recorded fuel pressures on the repaired car and the spare one. The spare has a Pierburg pump and recorded approx 3.68bar at idle, the repaired one has a Magneti Marelli pump and recorded approx 3.55 bar at idle. Both are comfortably over that needed for starting, though I suspect the Pierburg pump would cope better at high engine loads (the MM pump pressure dropped to around 3.42bar when the engine was revved in neutral - I didn't test this on the Pierburg). Of course, the difference could be caused by other factors than just the pump as they are two different cars and with different fuel maps.

I did originally try just the new UBP as I didn't relish replacing the ITP again, but it didn't seem able to prime itself so I had to swap the ITP. Also I noticed that if I unplugged the Pierburg UBP wiring whilst the engine was running, it would stop almost immediately. On the MM pump, it seems to idle for several seconds before finally cutting out which makes me wonder if fuel from the ITP is able to flow through it, which might also explain the lower pressure if the pumping element isn't as well sealed as the Pierburg one?

for info,my genuine Pierburg gives 3.55 bars at idle (via TOAF)