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Old 10-06-2012, 12:17 AM   #11
vintagerider
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Joined: Nov 2005
Location: the west
Oddometer: 1,996
Quote:
Originally Posted by 1100cruiser View Post
just looked at it again, there are the four wires on the pump wiring, whit,green,brown, yellow. all four are the same size. on the bike side harness, 1 big brown wire, green/white, yellow/red, and white/blue.
edit: Just dug up a '93-'94 ver. pump plate. All four wires to the harness plug are the same light gauge, 3 of which which pass through a single small 3 terminal electrical bulkhead fitting (as opposed to dual b-h fittings 95 and up). Unique to this style also is a welded grounding tang on the outside of the bulkhead fitting. So a single small b-h serves both the pump batt pos (but not pump ground) and the fuel gauge. Later style moves the pump power off this small b-h fitting and passes pump ground also through b-h rather than relying solely on p. plate for pump ground.

1) GREEN- pump pos terminal 2) Yellow-float board 3) White- float board. On the inside of the early style the pump's only ground is to a machine screw to which the fuel level slidre contact is also grounded via a connection to the hair wire between slider and board.

Therefore, as described by Liz, a separate pump ground brown wire p/n 2306543 with eyelet must be fitted under one of the tank mounting bolts (nut/stud if metal tank). A quick disconnect is fitted to connect to the chassis ground and to allow tank removal w/o undoing the pump plate bolt to release the ground wire ring terminal. Link to part and diagram (listed for early RS):
http://www.bmwmcchattanooga.com/show...ssembly=193255

>> The pump ground may become compromised by i) bad connection to the the internal ground screw. ii) broken or corroded tang on the outside of the b-h fitting. iii) loss of grounding of the pump plate via 2306543 brown quick disconnecting grounding wire. Of these three the last is by far the most likely.

>> Later style pump plate should retro fine and the pump will operate w/o 2306543 attached however the early style does have the advantage of being more leak resistant. Use of a more efficient pump with lower current draw is preferred on these.

As mentioned, the revised p plate have a second larger bulkhead dedicated to pump power via heavy gauge wire. If using the older style then particular attention must be paid to maintaining the grounding circuit and keeping all components in top condition to prevent under-fueling.

One advantage to the early style is that the larger dedicated pump blk-hd IS absent. This larger blk hd fitting is secured to the pump plate from the inside with a crimp ring and an o-ring seal which is not visible or serviceable. This o-ring may crack or the pressure seal lost from expansion over time resulting in a slow drip of fuel on telelever, the source of which is often difficult to diagnose unless you know what to look for. Diagnosis of the problem is made by filling the tank with two gallons and letting it set on the pp side for several hours. Fuel appearing on the pp which is not from the big o-ring is coming from the pump pwr blk hd..

/!\ always disconnect the pump plate harness before lifting the tank. It is not uncommon for the metal tank to ground out against the batt + post and fry the pump plate. For extra safety the battery ground wire should also be disconnected.
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It's what Liz said. Better title for this thread: "Early style 11xx pump plate" The '93-'94 had the early style pump plate. Upgraded in '95-'96. Identified by one electrical bulkhead. Not sufficient power capacity on those thin wires for the oem style pump. There should be a separate ground wire (brown) with a connector. Pull the pump plate. Time to refresh internal fat hoses anyway. Pump with have a date code. Probably marginal and should be replaced. Pop off the suction screen, rotate impellers, looked for broken ones, check bearings. In a pinch, clean/reassemble might restore svc temporarily but risk of engine damage from too lean (low pressure). Read crackhead's pump thread. The 69222 Bosch requires less current.

Heavy green: pump battery pos

Heavy brown: pump ground, pump motor grounded to pump plate also.

vintagerider screwed with this post 10-07-2012 at 01:42 PM Reason: dug up a '93 fuel pump plate
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