Alternator Replacement

[Kchop]

Hey Group,

Replacing an alternator in 93 K 75s. Just checking that I do indeed have to remove: the battery, fuel injection control unit/ storage tray and coolant recovery tank? 

Thanks,

[frankenduck]

Yes.

[Kaos]

Yes.

Impossible to argue an answer this resolute and concrete typed with this amount of determination.

[Kchop]

yes, I can imagine the associated expression,

[Kchop]

Hey,

So, pretty crestfallen. "new" alternator is in. Bike started right up, at about 2000rpm outputting about 13.6-13.8

Then, started blowing the 7.5 fuel pump fuse ( several times) when I was revving it up, getting the motor going. At low idle voltage outputting only 11.8 or so after new fuse and motor warmed up. Took it for a ride, settled back behind garage and fuse blew again.

Yes, brand new battery. New voltage regulator/brushes on alternator. Aftermarket fuel pump.
Same exact set up went on a 600 mile ride last year, no problem. Someone suggested a larger capacity fuse?

Just want to ride a bit....

[Kaos]

Check the pump's wiring, usually its a crapped out ground wire. They have a tendency to break near the connector or the float plate underneath the tank.
Check the pump for contamination and gunk (or throw in a fuel system cleaner booster to clean the fuel everything.
Also a kink (not the good kink) in the fuel hose may cause the fuel pump to over draw.
I personally test my pump with a 9v battery.
These are the cheap checks and fixes. You should not use a higher amp fuse because it may be an underlying electrical issue and could cause more damage and thus pesos to fix

[The Mighty Gryphon]

How old is your fuel filter?  Could it be blocked?

[Kchop]

I'll check the fuel filter...youre thinking the pump working hard to get the thought he blockage yes??

[Kchop]

I personally test my pump with a 9v battery.


Explain the 9v test if you can.

[Kchop]

@Kaos,

I'll try everything you said in the next couple of days. Not familiar with the float plate though...

[Kchop]

Gryphon & Kaos:

Let me ask some basic stuff: To check pump, should I remove from gas tank? Same for fuel filter, remove that little hose, remove from tank ? Am I just checking the ground wire visually or should I be running continuity test etc.

Thanks

[frankenduck]

I think what he means by float plate is the base plate for the fuel level sender and continuity as the connections pass through it.

You can use ring terminals to test the fuel pump in place.  (Alligator clips might also work but adds the risk of creating a spark in the gas tank!)



To test the fuel filter pull it out and try to blow though it in the direction of the arrow (towards the front of the tank.) You should be able to blow through it fairly easily.

[Kchop]

Frankenduck, thanks for the picture. Are the ring terminals connected to multi meter, am I testing for continuity or am I running a separate 12 volt source to it?

[frankenduck]

12V to the fuel pump to test it

[Kaos]

I'll check the fuel filter...youre thinking the pump working hard to get the thought he blockage yes??

Correct, and maybe a fuel hose that might have kink.

I personally test my pump with a 9v battery.
Explain the 9v test if you can.

Disconnect the power from the bike, fuse is usually enough.
Remove the pump from the gastank, keep the fuel hose that is connected to the pump and filter, but remove the filter.
Place the pump in a clean container which can hold fuel, preferably a bucket, add fuel, -enough for the bottom to be submerged and the hose end facing to the bottom of the bucket. Connect+ to + and - to min for both the 9v battery and the Fuelpump. It should prime and start a flow. Not as powerful as on 12v, but enough to see and hear it work.
Have a lid ready in case. You known... Boom.

I think what he means by float plate is the base plate for the fuel level sender and continuity as the connections pass through it.

Correct, however id start checking the wires on the outside instead of inside the tank. Because those tend to wear more often. And its easier to check

Gryphon & Kaos:

Let me ask some basic stuff: To check pump, should I remove from gas tank? Same for fuel filter, remove that little hose, remove from tank ? Am I just checking the ground wire visually or should I be running continuity test etc.

Thanks

both ways are easy.
In tank:
If you can get continues power to the pump by fidgeting a 12 to the connector and a ground you can check the flow inside the tank with and without filter.
Outside of the tank gives you more room to work with, principal with power is the same. However less safe

[frankenduck]

FYI: The smaller diameter terminal on the fuel pump is 12V+, the larger diameter is ground.

[The Mighty Gryphon]

Take the filter out to test it, better yet, if you don't know how old it iis replace it.  NAPA 3032 is a good replacement.  also when you replace it don't use the fuel line that comes with it.  That line is not good for submersion in fuel.  Good idea to replace the original line with the correct stuff which I think is SAE J10R13.

[Laitch]

Good idea to replace the original line with the correct stuff which I think is SAE J10R13.

SAE J30R10

[Kaos]

8mm inner diameter.

[The Mighty Gryphon]

SAE J30R10

I'm getting lesdyxic or something in my old age.

[jiggseob]

SAE J30R10 fuel line is the specification for submersible, that is gasoline inside and outside of the hose.  Various pressure ratings are available, 100-300 psi.  Brick fuel pump can only put out about 30 psi, so pretty much any fuel line we can buy will meet the pressure spec.  Don't just buy a reel of J30R10 fuel hose for general use, its purpose is to be submerged in gasoline, and gasoline tanks are generally kept cool.  Engine compartment temperatures get alot higher than fuel tank temperatures, that "submersible" fuel hose may not perform well at ambient temperatures of 200F+ often found in engine compartments.

While peering inside the tank at the filter of my K75RT, I saw an "aneurism", a bulged ballooned out section of fuel line on the filter. Replaced it all.  Lucky to have seen it and fixed it before it made me walk.

I'm not sure what caused my fuel hose aneurism.  Those fuel lines that were put in there by BMW in the 90s are getting old.  Also, no one, not even BMW, thought of ethanol in pump-fuel in the 90s.  So it might have been age, ethanol, or previous owner replacing it with non-rated line.  Take a flashlight and have a look.

[The Mighty Gryphon]

While peering inside the tank at the filter of my K75RT, I saw an "aneurism", a bulged ballooned out section of fuel line on the filter. Replaced it all.  Lucky to have seen it and fixed it before it made me walk.

I'm not sure what caused my fuel hose aneurism.  Those fuel lines that were put in there by BMW in the 90s are getting old.  Also, no one, not even BMW, thought of ethanol in pump-fuel in the 90s.  So it might have been age, ethanol, or previous owner replacing it with non-rated line.  Take a flashlight and have a look.

A lot of aftermarket fuel filters like the NAPA 3032 come with short pieces of hose and clamps.  Never trust that hose, it's not for use in the tank.  Use the right stuff.

[Kchop]

OK!!!, first off let me say that I felt like a genius for a little while, ok with the help of like six people on here. Is it possible to fall in love with the brick boys? Mechanically , of course.

1.working inside the gas tank is pure hell with these mitts, whoever has suggestions for lighting , I'll take it.
2. Alternator is in, outputting around 13.0-13.2 at 2000 rpm
3. Drained gas tank, looked like gelatinous sand in the deepest parts, yes there's overflow all over the garage floor. Really looked like less than 1.3 gallons remaining
4. cleaned and vacuumed gas tank.
5. bought Napa filter ( after blowing through old one and jetting some gas on my pants, etc)
6. re-used old hoses ( was before I saw the follow up posts) then...
7. NO MORE FUSES BEING BLOWN
8. half a tank of gas, started... running really rough, sputtering...added some seafoam.

After half an hour of riding , voila!!  so smooth

thank you everyone 

[Kchop]

https://www.amazon.com/kuosbiu-Pressure-Submersible-Automotive-Systems/dp/B0CNQ2CZ56/ref=sr_1_1_sspa?crid=3GOV6IM61H0NE&dib=eyJ2IjoiMSJ9.YvcgXA0MGUh_Ozq4b1oLXL5ZDcj1UVVUvR3M0OCPE4Y.sRGZ9ilJCtbVAAQxo9hlg87DFVrbbT8S88MuEYso6k0&dib_tag=se&keywords=sae%2Bj30r10%2B5%2F16&qid=1748901399&sprefix=sae%2Bj30r10%2B5%2F16%2Caps%2C115&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1

Something like this for hoses??

[Laitch]

Something like this for hoses??

Something exactly like that.