I have a 3 port Bosch FI pump D580463009 that came to me along with some other FI parts I purchased long ago. It had clearly been molested previously.

I decided to power it up. Yup, motor runs.

I decided to see if it would actually pump some alcohol since I didn't want to risk gasoline. Good thing . . . it leaks like a sieve.

Having nothing to lose, I decided to disassemble it. There was massive leakage out of the motor housing and the large O-ring that goes between the pump rotor base and the DC electric motor housing was clearly torn and rolled when I disassembed it and this is where the bulk of the leakage was coming from.

I'm wondering if someone can advise on what the criteria is for a core / rebuildable part since these clearly aren't cheap to rebuild nor are they easy to come by.

@914sixer
@dr914@autoatlanta.com

Here are some pictures for those curious about the intertnals of a 3 port rotor pump.

Rotor inlet & outlet housing:
Click to view attachment

Pump rotor and vanes:
Click to view attachment

Click to view attachment

The motor rotor, windings, and brushes:

Click to view attachment

And finally the inside of the motor housing / stator permanent magnets

Click to view attachment

Click to view attachment

I rebuilt a Bosch fuel pump from a Mercedes a few years ago. The only issue was that it leaked. Turns out it leaked in a couple places. I replaced the seal where the pump body meets the head of the pump, and also a seal where the electrical connector studs are. Both seals were hard as a rock. Pump works perfectly with no leaks after replacing the seals.

There are some DIY threads over on the Pelican board from guys rebuilding early 911 fuel pumps, which are very similar to the 914 pumps.

I have never attempted to build one. I just send them to a guy that has 35 years experience doing VW type 3 fuel injection stuff.

Can you please give the contact info for this service, as I have one I would like to have resealed.

Cheers,
John

There was someone on pelican selling the o-Ring Kits for the Bosch fuel pumps. I'll see if I can find the ad.

-Dennis

Mark has ad up on FS/WTB where he can send yours out to his guy $299 shipped. Honestly that is a cheap relative to Auto Atlanta's service at $395. I suspect either of these sources will do a great job.

What I was looking for is more info on how to tell if the core is even worth sending for a rebuild. Mine has a commutator that is pretty worn, burshes are about 50% used up, and obviously there is a lot of resudual rust / garbage debris that was in this pump that is surely gumming up the pressure bypass piston. I haven't had time to get over to Pelican forums but will take a peek to see what the 911 guys are doing.

After disassembling this one, I can tell you that it won't be an easy task to rebuild properly especially to replace brushes and to resurface the commutator.

Given that the whole pump electrical side is immeresed in the pumped liquid for cooling, this would be a challenging component rebuild that I really don't have the time to take on while my chassis is still not done.

I just plug the pump up to 12V and see if it runs for just a couple of seconds. If it runs it is usually a good candidate for rebuild. Stuck pumps are questionable. My guy will take the stuck ones and immerse them a couple of days to see if they will break loose. I sent in 6 pumps and only 2 were able to be rebuilt.

I am disassembling this same 3 port pump from my recently acquired 914 and found gas full in the body of the pump motor. I see the Oring in between the impeller housing but how could gas leaked into the motor housing?

Pump is running on bench now so if I know why gas was in the motor body, could I install it back to fire up the engine?

if the guts are not rusted to hell and the housing and top are not broken, it is rebuildable

Can I put the pump back to fire up just to see if engine runs for now? Is it normal to have gas in the body to cool the pump? I'd rather install 2 port pump if restoring the whole car, which is later on. Thanks.

I believe the pump is liquid cooled by the pumped liquid.

Look at the picture of my pump body without the rotor and vanes in place. There is a hole there that leads directly from that pump side containg the pumped liquid directly into the pump motor body. The hole is completly open connecting the rotor vane pump cavity to the motor rotor/stator assembly.

It is esentially a DC motor running inside a can full of the pumped liquid.

The reason the inside of my motor "can" is so dirty is that is all the residual particulate debris that is small enough to go though the fuel filter that has been carried into the pump housing and the motor housing by the gasoline.

Your DC motor armature appears a bit different than mine. Yours appears to have some winding covers that likely serve to help cut down on the viscious drag of the armature as it rotates though the fluid.

I find this pump to be interesting but still haven't had much chance to get over to the bird site to see if I can find more info on it's design.

Thanks for the fast response. I'll put RTV onto the Oring of the body for extra seal and close it and leave to dry. I'll install tomorrow and hopefully the engine will fire up so we can plan next phase for the car.

The 2 port pump upgrade and relocate to front will wait until engine drop for Tangerine stainless fuel line upgrade same time.

@Bmw635
I'll caution you that RTV usually isn't a good "extra seal" for O-rings. O-rings are required to roll back and forth to a very small degree to maintain a seal. RTV hardens and then prevents that movement and eventually fails.

Won't hurt for the short term just to try to get running but beware that a new fresh & pliable O-ring and clean, smooth sealing surfaces are what makes an O-ring seal sucessfully, not additional sealants.

Give it a try - just be aware of the downside.

@dr914@automobileatlanta.com

Thanks Doc!

I think that seals the deal on mine. It looks to me like the pump housing base has a "keyway" notch that the previous disassembly created as they likely tried to pry the pump body and armature up out of the can or maybe hammered on the pump end shaft to put the housing back in the can.

I just did a Google search of the bird site and I can't find any pictures of pump housings that have this "custom" notch that mine has.

Probably not a good core.

May stash the parts away in a corner for a day when I have time for a science project. Too busy for now.

10 years from now, my wife will ask why I'm keeping these parts.

@Superhawk996 ,
understood. Using gas resistant rtv and just putting it between the Oring and the top of the can to help the Oring expand to seal tighter. The Oring is still pliable to fold into 4 circle like figure 8 so may be the pump was rebuilt or replaced about 10-20 yrs only, not 50 YO Oring.

Since the plastic hardline need replace, I figure relocate 2port pump to under tank at same time later on. Thanks.

We had started working on a rebuild kit. Found that the tolerance on the o-rings are critical.
Too tight will not turn (small oring), too loose fuel bypasses across the top of pump section. We planned to make some from viton, but there are no off the shelf oring sizes that seems to work. Good news is we can make anything, but we are still trying to figure out exactly the size we need. That is as far as I have gotten so far.

@Mikey914

Some on the bird site seem to have some success but no follow-ups w.r.t. longevity and how well the pump kept working.

The good news (for me) is that you probably have 10 years to invent a seal kit before my wife figures out I've kept these parts around. Don't forget the O-ring under the electrical connector portion.

It appears from my pump disassembly and the pictures on the bird site that the seals are/were not typical circular section o-rings but square section seals. While an o-ring will likely work, it won't be "just right". Sounds like that is what you have found as you tried to find just the right O-ring.

Yes, we experimented with stock O rings as the originals appeared to be that. Our conclusion was exactly that, The square shape would allow for a more precise tolerance.
We had noticed on the 4 we played with that the lower seal wasn't the issue for the most part. The upper section was when they had all failed. If you're gonna do it, might as well do them all. I do believe that the reason they are selling a service is that the disassembly and re assembly of the lower end does offer some challenges.
Mark