furgo
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Joined: September 06, 2016
Posts: 944
Location: Southern Germany
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 Posted: Sun Oct 01, 2017 11:59 am Post subject: Inside the FI electric fuel pump (043 906 091) |
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| [url=https://www.thesamba.com/vw/forum/viewtopic.php?t=687527&start=0&postdays=0&postorder=asc&highlight=]Inside the FI electric fuel pump (043 906 091)[/url] |
This is a bit of a long one, so if you're not interested in the intro, feel free to skip to the disassembly bit to see the insides of the pump.
After having spent quite a few time in the last weeks diagnosing fuel injection, I've also spent some time testing individual components in isolation to better understand how they work.
One of them was the fuel pressure regulator (FPR). I could not, for the life of me, get to open the diaphragm by applying vacuum. I must say though, that my hand pump goes only to 25 mmHg, which I don't know if it's enough.
Then I tried on my spare one, same behaviour. Holds vacuum, but does not seem to open the valve. So either it's supposed to work like this (i.e. it needs combined pressure AND vacuum) or both of them are broken. But I can't imagine they are, particularly as at least the one on the bus holds and relieves the pressure at the given specs. So if the pressure is regulated, and it holds vacuum, the spring and the diaphragm should be ok.
Long story short: I decided to test with some pressure on the bench, so I put together a pump and FPR assembly. That didn't go well: my spare pump, which the seller had reportedly tested with success, did produce a nice sound, but no output of fluid at all.
What made me wary was that when shaking it a bit something rattled inside. From having cleaned up my main pump a while ago, I knew no such rattling was to be expected.
With a non-working pump, I had nothing to lose, so I cracked it open and thought I'd share the process here.
Disassembly
In the beginning there was a Bosch 0 580 463 016 fuel pump and a pair of pliers.
I started with the pliers on the output side, where the aluminum case holds together the plastic base with the fuel outlet and the electrical terminals. I essentially flattened all the pleats on the case by carefully twisting them and then squashing them.
This way I could then easily pull the plastic lid with the terminals, revealing the rotor and the magnets:
1. C-Clip on top of the shaft holds the rotor in place
2. Top view (from inside to outside): commutators, armature, permanent magnets.
The brushes were on the other side of the plastic lid. Notice the grooved pattern: I'm assuming it's to have more surface area of contact with the rotor's commutator.
Notice also the rubber O-Ring surrounding the lid. It's what keeps the fuel inside the case.
3. Spring-loaded carbon brushes and power terminals
Did you see that C-clip at the top of the shaft in the first picture? It's what's preventing the rotor from sliding out of the shaft, and it's a devil to remove. It's opening is fairly wide, so my C-clip pliers did not work and I had to resort using a pair of dental steel picks, each pushing one end.
As a reminder, the FI fuel pump is a roller-cell pump. It uses small metal rollers pocketed inside an eccentrical rotor disc to squish the fuel and generate high pressure. I won't delve into that, but a diagram is always useful:
4.Electric fuel pump diagram, from the Bosch L-Jetronic documentation.
The Bosch pump has also:
• Outlet check valve: keeps the fuel from returning to the pump with the engine off and eases restarts by holding the pressure on the fuel rail
• Inlet pressure limiter: a relief valve that returns fuel to the tank if the internal pressure becomes too high
• Inlet mesh filter (not depicted on the diagram)
With the C-clip removed from the top of the shaft, I could also remove the rotor and the permanent magnets, revealing the roller cell enclosure. At that point I noticed what was rattling:
5. Roller cell assembly.
Both the left and right screws were fairly loose. They did still hold the assembly, but I assume too lose for the metal rollers to be tight on their vertical axis and to build up pressure. That was probably the issue with the pump not delivering. In any case, I removed the top part of the case to reveal the rollers and the disk. Nice.
6. Eccentric disk and rollers revealed.
I could remove the last plate containing the disk and the rollers, but there was not much more knowledge to be gained there. Nor were there other parts to be serviceable. For that reason I chose not to undo the last C-clip. The fact that I knew it was a pain to remove might have played a part in there too.
7.Roller disk, metal rollers and pressure limiter.
Notice the plastic cog: it's what engages the rotor and mates the forked cog at its bottom end.
I assume that the goldish ball on the bottom right-hand side is the internal pressure limiter.
Finally, here's the disassembled fuel pump in all its glory
8. Fuel pump components (top to bottom): cover (outlet, check valve, power terminals, brushes), C-Clip, washers (x2), rotor, washer, permanent magnet assembly, roller cell assembly, case and inlet.
Some shots of individual components follow:
9. Rotor
The rotor. The gouges in the rotor were done by a fly cutter and are areas where weight was taken out for balance of the armature –the motor inside the pump runs at fairly high RPM. Thanks to asiab3 and raygreenwood for shedding some light into this.
The commutator has a fairly deep groove carved by the brushes, so it probably has its share of miles.
10. Carbon brushes.
The brushes. Spring-loaded to exert pressure and contact the commutator.
11. Roller cell assembly.
Roller cell assembly. Two plates: the eccentric that holds the disc and the rollers, and the one that closes it on top.
12. Permanent magnets housing
13. Detail of the two permanent magnets inside the housing.
Permanent magnets. Fitted on their own case inside the aluminum case.
Reassembly
At this point I'd seen enough to understand how the thing works and fixed the rattling sound, so it was time to reassemble.
Other than ensuring that this time the screws were bloody well tight, the reassembly was simply the opposite of the disassembly. Except for one critical bit:
14. Threads pull the carbon brushes to be completely recessed.
15. Thread fixed before cover assembly
The brushes needed to be out of the way to slide the cover back in and not to collide with the commutators. I have no idea how they assembled this at the factory, but I went the creative path and used some thread to pull them as far back as possible during reentry.
Once I had the cover back in, I cut one side of the double thread and pulled the other side. Miraculously, it worked.
Finally, I used a hammer and a punch to "crimp" the aluminum case and the cover. The marks of the previous pleats were still there, so it was a matter of aiming and punching each point carefully.
16. Case and plastic cover reassembled.
It was the part that worried me most, as I didn't know how it would work out. There was a high chance that it would: a) look like crap and b) not hold the pressure inside the pump.
I was quite happy and surprised with the result, it turned out allright. I should have also said that tt's the O-ring that keeps the fuel from escaping the pump by friction on the case. The pleats on the case are only there to hold the lid.
Testing
Finally, I did some testing with denatured alcohol and power. I do not have pictures, but I had a pretty rustical setup with a bucket for the delivery, another one containing the "fuel" supply, and a 12 V power supply. In any case I'm happy to report that:
• This time the pump worked and could deliver fake fuel. Yay.
• There were no visible leaks from the lid. I tested with an unobstructed outlet and under pressure with an FPR at the output.
• Current consumption with FPR attached was 3.65 A @ 14 V
• The stink of the denatured alcohol killed the stink of fuel previously contained in the pump. Still undecided on what's worse.
That was it!
Ripping the guts of the fuel pump out does certainly not make me an expert, but if there are any questions I can answer, I'll be more than happy to oblige.
Specs
From Bosch 0 580 463 016 datasheet:
- 2.5 bar
- 67 - 137 l/h
- 550 - 1140 cc/30 s
- 12 V, 30 W
- 8 mm outlet at pressure side
- 12 mm inlet at suction side, with integrated mesh filter
Part numbers
Bosch #: 0 580 463 016 (original, 30 W, NLA, replaced ...010), 0 580 464 085 (universal, turbine-style?, 54 W, currently available), 69469 (turbine-style pump, not roller cell, currently available)
Volkswagen OE #: 043 906 091
Porsche OE #: 923 094 906 35
_________________
'79 Westy, P22 interior, FI 2.0 l Federal, GE engine (hydraulic lifters)
Decode your M-Plate
Last edited by furgo on Mon Oct 02, 2017 6:14 am; edited 8 times in total |
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