bdutton Posted February 24, 2017 Share Posted February 24, 2017 Hello citizens of VFRD, I'm a new member here, but that's not what this post is about... Now that the weather is starting to get halfway decent, I figured it's time to diagnose the issue with my bike that presented itself at the end of last season... Engine was warm i didn't just start revving the snot out of it while cold. The fluctuation in rpm and the engine dying completely all happened with the throttle at about 3/4. It's a fuel or spark issue. I thought maybe a clogged tank vent but same symptoms persist when running with open gas cap. When I go to restart the bike, won't run unless I twist throttle pretty good which results in large fireball out of muffler (neat but still an issue) then it idles normally. Give any kind of throttle and it's a repeat of the video. Bike is a 96 VFR750. I'm leaning towards petcock and or fuel filter, may also also be plugs/coils. I hope it isn't carb related because those are absolute voodoo witchcraft to me. Any help or suggestions would be greatly appreciated. This is the only video I have of the issue at the moment. Link to comment Share on other sites More sharing options...
coupedupsubie Posted February 25, 2017 Share Posted February 25, 2017 I would start with the fuel filter then checking the pump. Hard to say from there. Link to comment Share on other sites More sharing options...
Member Contributer Dutchy Posted February 25, 2017 Member Contributer Share Posted February 25, 2017 take the top cover off the fuel pump and see if it does this: http://vid113.photobucket.com/albums/n206/Dutchy_748/VIDEO0064_zpscda3d494.mp4 the "points" on top should be "clicking", for that is how the pump operates, by having the inside come up and by "shorting", lest it slide back. IOn the vid you see the brand spanking new points. Link to comment Share on other sites More sharing options...
bdutton Posted March 6, 2017 Author Share Posted March 6, 2017 Thanks for the reply Dutchy. Just saw this. Haven't had access to internet. I'll check that next time I get home. Link to comment Share on other sites More sharing options...
bdutton Posted March 23, 2017 Author Share Posted March 23, 2017 Finally back state side, I have all the fairings off. How do I take the cover off the fuel pump?Sent from my Pixel XL using Tapatalk Link to comment Share on other sites More sharing options...
bdutton Posted March 23, 2017 Author Share Posted March 23, 2017 Fuel pump also appears to have a Mitsubishi logo on the top? Sent from my Pixel XL using Tapatalk Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted March 23, 2017 Member Contributer Share Posted March 23, 2017 I assume you've got a vacuum petcock on the 4G; if that is giving grief (e.g. not opening fully due to debris or age/perishing) then I suspect you'd have a similar problem. So check the vacuum line is intact with no cracks or splits, then try applying vacuum (a good mouth suck would do) and see if you get a good gravity fuel flow through the petcock. They are not difficult to rebuild, and are a known failure point on many bikes (my VTR1000 and ST1100 for example) with age. Link to comment Share on other sites More sharing options...
bdutton Posted March 25, 2017 Author Share Posted March 25, 2017 Mouse nest in snorkel. This may actually be the cause of my problems. Air starvation... Sent from my Pixel XL using Tapatalk Link to comment Share on other sites More sharing options...
Member Contributer MaxSwell Posted March 26, 2017 Member Contributer Share Posted March 26, 2017 3 hours ago, bdutton said: Mouse nest in snorkel. This may actually be the cause of my problems. Air starvation... Sent from my Pixel XL using Tapatalk I've sung that song a couple of times. Made for rough running every time. So I'd recommend everyone check for this when buying any used Honda. Esp. with bikes stored in pole barns. Link to comment Share on other sites More sharing options...
squirrelman Posted March 31, 2017 Share Posted March 31, 2017 Those damned rodents again !! You might need a proper carb cleaning. Link to comment Share on other sites More sharing options...
bdutton Posted April 6, 2017 Author Share Posted April 6, 2017 Those damned rodents again !! You might need a proper carb cleaning. They're off the bike, have a buddy coming down tomorrow or Saturday to rebuild/replace seals and adjust the jets if necessary. I did the oil, plugs and coolant last week. Plugs appeared to be burned and covered in oil. I think I'll be doing a compression test before everything is completely back together.Sent from my Pixel XL using Tapatalk Link to comment Share on other sites More sharing options...
bdutton Posted April 8, 2017 Author Share Posted April 8, 2017 Started to put the bike back together just for kicks before even touching the carbs. Some combination of replacing the fuel filter, fuel pump, spark plugs and air filter including removing the mouse nest, has caused my annoying misfire to go away. Now it goes to redline without hesitation. The throttle is on the sticky side now however. Gonna pick up some dry graphite lube tomorrow and hopefully that alleviates the symptom. Sent from my Pixel XL using Tapatalk Link to comment Share on other sites More sharing options...
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