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96 R850R - Blowing Fuel Pump Fuse


mrmadagascar

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mrmadagascar

Hey folks, new to the forum! I ride a 96 R850R, and am based in the SF Bay Area

 

I made an unfortunate mistake the other day while reinstalling my battery, which involved a slip, causing the metal clip of the battery strap to arc between the positive lead and the tank, resulting in some fairly spectacular fireworks.

 

I managed to flick the strap out within 3 seconds, but the damage was done, resulting in my fuel pump not turning on.

 

I pulled the pump out of the tank, and it's still working fine, so the problem appears to be further down the line.

 

Since then, I've checked the fuel pump relay, and everything in between (Relay seems to be fine, putting out an appropriate amount of power), but no matter what, the fuse will blow every time I plug the pump back in, otherwise, the fuse stays intact when the power turns on.

 

Why would it only blow when the pump gets plugged in?

 

The connector on the pump side got a little crispy, so I cut it out and replaced the wiring.

 

The line from Battery -> Pump goes like this:

 

Battery -> Fuse -> Relay -> Injectors -> Lambda Sensor -> Fuel Pump

 

Thanks for any ideas!

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Afternoon mrmadagascar

 

What amp fuse are you installing in cavity #6? It needs to be at least a 10 amp fuse.

 

Otherwise-- see if the fuel pump will operate (outside of the tank) with a 10 amp fuse in the circuit.

 

If it only blows the fuse with the pump hooked up then that sort of points to an undersized fuse OR a pump that is drawing too much current.

 

You don't have the pump (pressure side) hose deadheaded do you???

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mrmadagascar
Afternoon mrmadagascar

 

What amp fuse are you installing in cavity #6? It needs to be at least a 10 amp fuse.

 

Otherwise-- see if the fuel pump will operate (outside of the tank) with a 10 amp fuse in the circuit.

 

If it only blows the fuse with the pump hooked up then that sort of points to an undersized fuse OR a pump that is drawing too much current.

 

You don't have the pump (pressure side) hose deadheaded do you???

 

Heya!

 

I'm using 15A fuses (Same as what was originally in the bike)

 

Admittedly, this may show some ignorance, but what do you mean when you ask about the pump hose being deadheaded?

 

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Admittedly, this may show some ignorance, but what do you mean when you ask about the pump hose being deadheaded?

 

Afternoon mrmadagascar

 

Pressure side hose disconnected & plugged off.

 

If the pressure hose is plugged off then the fuel pressure regulator can't allow excess fuel to flow back to tank through the return hose so the pump has to work harder.

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mrmadagascar

 

 

Pressure side hose disconnected & plugged off.

 

If the pressure hose is plugged off then the fuel pressure regulator can't allow excess fuel to flow back to tank through the return hose so the pump has to work harder.

 

I've been testing with the pump disconnected (naked on both intake and pressure side) from the rig other than the electrical connections. Does the pump need to be submerged in order to draw the correct ammount of power?

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I've been testing with the pump disconnected (naked on both intake and pressure side) from the rig other than the electrical connections. Does the pump need to be submerged in order to draw the correct ammount of power?

 

Afternoon mrmadagascar

 

Yes & no-- the pump is lubricated by the fuel it pumps & the pump is also cooled by the fuel it pumps through it so running the pump with it not submerged in fuel can ruin the pump.

 

If you run it outside of the tank then only run it for a couple of seconds to prevent pump damage.

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mrmadagascar

I tapped the pump connectors to the battery, and the pump did start up with no issues. It still blows the fuse when connecting via the *actual* connector.

 

I guess the theoretical next step is for me to put it back in gas and try to start it there?

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Afternoon mrmadagascar

 

Try to momentarily hook the pump to the battery again with a 10 amp fuse in the circuit. If it blows that stand alone fuse then your pump is drawing too much power (or the impeller is starting to seize due to no lubrication)

 

OR, there is something wrong in your pump connector (like a short)

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mrmadagascar

Howdy DR

 

Got home from work, tried turning the bike on again, this time with a 10A fuse, but no dice (it blew) :(

 

How could I test for a short?

 

Should I try submerging the unit in fuel in attempt to lubricate? (Now I'm worried I damaged the pump while testing)

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Should I try submerging the unit in fuel in attempt to lubricate? (Now I'm worried I damaged the pump while testing)

 

Morning mrmadagascar

 

Yes & no, you should probably try to submerge the pump to test it but using gasoline is very dangerous when not enclosed inside the tank.

 

I would suggest you use something less volatile (like mineral spirits or kerosene).

 

You might also try testing with the pump unit wire harness plugged in but the actual power wire removed from the pump stud.

 

Are your DEFINITELY blowing the fuse?-- remember the pump will only run for a couple of seconds at key on then won't come on again until the engine is cranking.

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I wouldn't try doing any "testing" with gasoline present, especially if you suspect electrical issues. It only takes a single spark to make a bad day. Besides, operating the pump momentarily outside the tank should not cause it to seize. I find it odd that you're blowing only the fuel pump fuse. Is the pump building any pressure?

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mrmadagascar

 

You might also try testing with the pump unit wire harness plugged in but the actual power wire removed from the pump stud.

 

Are your DEFINITELY blowing the fuse?-- remember the pump will only run for a couple of seconds at key on then won't come on again until the engine is cranking.

 

Interestingly, I just tried plugging in the fuel plate/harness in without the pump, and the fuse still blew.

 

It's definitely blowing every time I turn the key on, and the unit is plugged in.

 

I tried this method with both 10A and 15A fuses.

 

I checked the power at the fuse, and it's correctly supplying 12V at key start to pressurize the pump, then it drops off.

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mrmadagascar
I wouldn't try doing any "testing" with gasoline present, especially if you suspect electrical issues. It only takes a single spark to make a bad day. Besides, operating the pump momentarily outside the tank should not cause it to seize. I find it odd that you're blowing only the fuel pump fuse. Is the pump building any pressure?

 

Good call, cheers :)

 

Not sure how I could check for pressure build up, but I've been testing it naked on both ends.

 

As noted in the post above, the fuse is still blowing when JUST the plate connector is connected.

 

When I turn the key on, the fuse blows simultaneously - doesn't even give the poor pump a chance to turn on :(

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Afternoon mrmadagascar

 

Well-- if it is blowing the fuse with the pump pass-through plugged in but NOT blowing the fuse with pump pass-through unplugged but STILL blows the fuse with the pump unhooked then your problem is something wrong with the pass-through wiring or the actual pass-through connections on the power side.

 

SO- use an ohmmeter & isolate EXACTLY where the pump power wire is grounding out the pass-through plate. Maybe it's the solder joint of the power-side-circuit plastic pass-through isolator.--(that would be my guess anyhow).

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mrmadagascar

Thanks for all the insight, will try to dig in to that once I'm home.

 

Would this have been specifically caused by the arcing battery?

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Would this have been specifically caused by the arcing battery?

 

Afternoon mrmadagascar

 

Sure (IF) the arcing caused something in the fuel pump pass-through power side to melt & go to ground (plastic pass-through connection comes to mind here)

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  • 3 weeks later...

Wanted to make sure to circle back:

 

The plate ended up being the problem - one replacement and some hacky wiring for the new connector later, she's back up and running :)

 

(Then, a week later the throttle cable snapped...oh the joys of motorcycles.)

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