Magneti marelli surging
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Stellar HDF Member
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From: mid Michigan
Magneti marelli surging
99 with 110,000 miles. Started yesterday then ran ok for a short while now it's all the time. Acts like it wants to run then acts like it's going to die, just goes back and forth seams worse without the power commander hooked up. Tried that plugs and fuel. I'm thinking fuel pump, was wondering how to test it or injector's.
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Stellar HDF Member
Joined: May 2015
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From: mid Michigan
Looks like I'll be trying a new pump to it out of tank to test. With auto zone gage took a bit to build psi, got to 60. There is no volume to it the as soon as it the release vavle it just has a small stream and psi goes to 0.
Are the after market ones any good or should I stick with Harley at 4 times the cost or more.
Are the after market ones any good or should I stick with Harley at 4 times the cost or more.
Last edited by xcbullet; Oct 10, 2017 at 06:06 PM.
Stellar HDF Member
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From: On a Lake, not far from the Gulf
Why don't you first try pulling any trouble codes? Did you change the fuel filter when you change the pump? Do you have the service manual? There are diagnostic flow charts in there. The proper test for PSI on the fuel pump is testing with the pump in the tank.
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Stellar HDF Member
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From: mid Michigan
Cooling off at gas stop after changed plug wires. All good now. Yes put new filter with pump. Thanks for reply. I'm so relieved it was something simple. It was hard to tell at first as it didn't do it all the time. Those Accel 300 race wires lasted 40,000 miles, won't use glass wires again on the bike. Have stock wires now, as they didn't have the SE wires in stock here.
PS yes have manual. Used it to find psi for pump and matched from summit. Also same brand that I took out of bike.
PS yes have manual. Used it to find psi for pump and matched from summit. Also same brand that I took out of bike.
Last edited by xcbullet; Oct 13, 2017 at 06:40 PM.
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From: mid Michigan
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Stellar HDF Member
Joined: May 2015
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From: mid Michigan
Update on the pump. It's doing good, but had to change the tune on low side of map. At first no issue. Then when along side a Chevy Impala at a light I gas her to get up and go and it stumbled bad. This was like a week later of it running fine. So I'm checking things and never find anything wrong. It does 100 mph without starving for fuel, so figuire pump is fine. Did notice last weekend was getting couple mpg better. So thinking it most be lean do to the pump being 42psi rated. Stock pump tested 60 psi but manual stated 42psi but that most be the regulator. Any ways changed tune & it's seams better than before. If had to do over again I would get the pump that is rated at 50psi (says for Renault). The nose on that pump looks just like the Harley one, the one I got is shorter. Kinda like it being shorter as this keeps the motor part of pump in the gas longer , it gets hotter than you think in the tank. The 50 psi would take till the next month as summit doesn't stock it and has to get it from Walbro, it was a few $ cheaper though. That's why I decided to stick with what I have. I could of got both those pumps and still been just over 1/2 the cost of the Harley pump. The only thing is these pumps don't come with the sock screen or anything just the pump. Just wanted to be clear so if anyone wants to get a cheaper Walbro pump down the road.
https://www.summitracing.com/parts/vpn-aou195
https://www.summitracing.com/parts/vpn-aou195
Last edited by xcbullet; Oct 26, 2017 at 11:30 AM. Reason: Link
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Stellar HDF Member
Joined: May 2015
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From: mid Michigan
UI wanted to update this thread as to what is a good cheap pump for MM injection system. I got a different one than mentioned above. It's 50psi for Chevy and Buick and they stock it at summit. I couldn't be happier, this pump comes with a check vavle like the stock Harley and is nice and quiet. Loaded my old map before the tweeked ones for the other pump. Now I have my take power back and this bike is a joy to ride again.
https://www.summitracing.com/parts/vpn-5ca400bx
If you get one don't forget the strainer.
https://www.summitracing.com/parts/vpn-5ca400bx
If you get one don't forget the strainer.
Last edited by xcbullet; Feb 27, 2018 at 11:19 AM.
Road Master
Joined: Jul 2010
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From: Hawaii
Has anyone used one from the Fuel Pump Factory?
https://www.fuelpumpfactory.com/coll...classic-custom
It is supposed to be a direct replacement and looks just like the one in the parts diagram. I am getting ready to replace the filter, pump and lines in my 2000 UC with 60,000 miles. It has been stumbling if I crack the throttle too quickly at 2200 rpms. It doesn't happen if I do it slowly or in any other rpm range.
https://www.fuelpumpfactory.com/coll...classic-custom
It is supposed to be a direct replacement and looks just like the one in the parts diagram. I am getting ready to replace the filter, pump and lines in my 2000 UC with 60,000 miles. It has been stumbling if I crack the throttle too quickly at 2200 rpms. It doesn't happen if I do it slowly or in any other rpm range.