Gen 1 down on power need HELP !

tak82 said:

I stated in my original post I cleaned screen and blew out pump filter. I completely tore pump assembly down. Issue definitely isn't a dirty filter. You're right tho pump pressure could vary from bike on stand and bike under load. I'm ordering stick coils and a pump and starting there.

Click to expand...

Not trying to be rude, but it seems like you don't know how these pumps work. The pre-pump sock/screen is indeed easy to clean, but the post pump filter is sealed into the plastic housing and is nearly impossible to remove and clean (if you've somehow done this I'd love to see pictures). Blowing air through it will not clean it... it will just move the restriction around. Flow testing a pump assembly at pressure will tell the tale, and I recommend you do that; it's not particularly difficult.

Second, free revving it on the stand is not "under load". Under load is 2nd gear or higher, 100% throttle, above 10K rpm or so.... trust me when I say there is a LOT more fuel demand there than in neutral on the stand. If you do not have a way to display or log fuel pressure "under load", an AFR readout (again) 'under load" will go lean if the pump is having a hard time (IE, fuel pressure dropping). They can drop pressure from a faulty pump, clogged filter, kink in a fuel line, or a drop in voltage to the pump.... but all of those will show the dropping fuel pressure under load symptom.

If you have stable pressure under load and it still gets lean up top, then you have an injector problem... It's really that simple. But none of these tests can be performed on the stand, you have to have accurate measurement under load. If fuel pressure and AFR's are acceptable and there is no misfire present (but it's still down on power), then you have a dynamic compression issue... which could be anything from the throttle not opening all the way (to include the secondaries) to a hurt motor or flat cams.

And to back Gaz up here, I've been down this road with more than a few pumps, and they all have displayed the same set of symptoms you are describing.... but I've always used instruments to diagnose it (gauges and logging) rather than just throwing parts at it. An AFR gauge and pressure testing rig will cot less in the long run, and you can move them from bike to bike throughout your fixing career.

/soapbox

EDIT: AFR's are indeed Air-to-fuel-ratios, and they require some sort of aftermarket gauge/measuring device to be monitored on a first gen..... they are typically called "wideband gauges" by the aftermarket. Most people in the business of testing/tuning/diagnosing repairs or engines have one or two laying around.

Hoping to get this revived cause I'm still having issues. Thanks Spazona for the input, I definitely appreciate everyone's inputs. I do understand how the fuel put works and the internal filter. Here's the latest. The miss is slight but it is from idle thru revs, pretty consistent. I've road tested the bike and it is down on power and when throttle hard there is a hesitation. I've checked pressure and flow rate at pump and they are both well within specs. I replaced plugs, originals looked all identical in color but replaced anyways. Tested stick coils and they were good but thinking there could be a torn boot I replaced them.Still same problem. Checked cylider compression. Pulled injectors, tested good but to eliminate the possibility I swapped the injectors, throttle bodies, tps. Still the same. I have a PCIII which I disconnected and still same problem. Also flow rate on fuel pump is about 200ml. Checked it 4 times. Have pulled the harness apart to look for corrosion, none. Have checked for kinked or bad wires, none. I'm not new to motors, I've been working on cars and bikes for over 30 years. Any thoughts ?

I'm pulling my hair out on this. To recap I have a miss from idle thru most of the rpm range. I've been going by the service manual. I've replaced plugs, stick coils, and complete throttle body set up with NO change. Checked fuel pump has proper pressure and flow rate. I checked valve clearance. All were within specs except one exhaust valve that was a little tight. It still had .005 clearance. I did not adjust that valve. I ran bike in dark and looked for spark or arching, have pulled ever connection and looked for corrosion. I pulled on the harness trying to find a broke wire. I have notice the 3 yellow wires coming from the stator are damn hot. They get hot within 1 minute of running. I checked voltage coming form stator and it's 56-57 across the board at 4k rpms. The ohm are .03 or .003 depending on what setting I'm using. So I believe the coils are not shorted or open, is that correct ? With a volt meter on the battery the voltage is 13.9-14.1 from idle thru a rev up. Disconnecting the headlight does not make much of a difference. Does that sound like the regulator is working correctly ? The battery has 12.7 volts and maintains it overnight. I checked 3 stator wires and connectors and they seem fine. Also, would the regulator not working right cause a miss in the coils or injectors ? I know the voltage for coils can be touchy. Any help is really appreciated. I've been talking with a local service manager ( he's a sportbike guy by nature) and he's kinda clueless. But I just found the stator wire issue. The bike is in excellent condition, hasn't seem much rain, always cleaned, never wrecked.