1 Fuel pump issue? Sun Mar 16, 2014 9:24 am
Rabidchiwawa007
Platinum member
Hello all,
This is in regards to a 1992 k100rs. I've been having some issues with the bike dying on me. This has happened when it's on a cold start, and today it died on me while I was riding and pulled the clutch in to shift. The battery still turns the starter nice and strong, so I don't think it's that.
When it dies, I notice that the fuel pump drops out. When it died on me today while riding it, I noticed a complete loss of electrics (at least at the instruments and pump).
It was strange. The electrics then came back as soon as I shifted it from first to neutral (after I had pulled over). When I tried to start it again, I could hold down the starter button and hear nothing from the fuel pump.
It eventually came back and I was able to ride on my way. It feels like it's starved for gas a little bit though.
I noticed a difference in running maybe a couple weeks ago and it's only worsened to where it is now. I had originally thought that maybe the injectors were a little dirty even though they've only got around 6-7k miles on them.
I have a fuel pressure gauge hooked in now at the back of the fuel rail. This was actually my intended question originally: where do I hook up the pressure gauge to test the pump itself? Which way does the fuel actually flow through the rail. Front to back? Back to front? As of right now, everything looks normal. I do see a drop in pressure as I open up the throttle in to higher RPMs though. It sits at about 33 psi, and when I open the throttle to around 3-4k rpm, it drops to about 25 psi or so. I assume that's due to the vacuum connection to the FPR.
I can also hear a number of different sound ranges from the fuel pump. Being a musician gives me a good ear for what pitch the fuel pump is emitting, and I've noticed it's higher and stronger sometimes, and sometimes it's lower and weaker.
Is any of this a sign of a failing fuel pump? Could it be anything else? I've gone through recently (probably 6 months ago) and checked /cleaned all of the electrical connections.
This is in regards to a 1992 k100rs. I've been having some issues with the bike dying on me. This has happened when it's on a cold start, and today it died on me while I was riding and pulled the clutch in to shift. The battery still turns the starter nice and strong, so I don't think it's that.
When it dies, I notice that the fuel pump drops out. When it died on me today while riding it, I noticed a complete loss of electrics (at least at the instruments and pump).
It was strange. The electrics then came back as soon as I shifted it from first to neutral (after I had pulled over). When I tried to start it again, I could hold down the starter button and hear nothing from the fuel pump.
It eventually came back and I was able to ride on my way. It feels like it's starved for gas a little bit though.
I noticed a difference in running maybe a couple weeks ago and it's only worsened to where it is now. I had originally thought that maybe the injectors were a little dirty even though they've only got around 6-7k miles on them.
I have a fuel pressure gauge hooked in now at the back of the fuel rail. This was actually my intended question originally: where do I hook up the pressure gauge to test the pump itself? Which way does the fuel actually flow through the rail. Front to back? Back to front? As of right now, everything looks normal. I do see a drop in pressure as I open up the throttle in to higher RPMs though. It sits at about 33 psi, and when I open the throttle to around 3-4k rpm, it drops to about 25 psi or so. I assume that's due to the vacuum connection to the FPR.
I can also hear a number of different sound ranges from the fuel pump. Being a musician gives me a good ear for what pitch the fuel pump is emitting, and I've noticed it's higher and stronger sometimes, and sometimes it's lower and weaker.
Is any of this a sign of a failing fuel pump? Could it be anything else? I've gone through recently (probably 6 months ago) and checked /cleaned all of the electrical connections.
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1968 BSA Lightning
1991 BMW K100RS 16v with K1100LT fairing