1984 VFR 750 starting problems

Hello, I purchased the bike 3 weeks ago and have been driving everyday with no trouble until recently. A few days ago it rained heavily over night and the bike was very wet in the morning when I went to leave work. It started but seemed to struggle to really run. I was able to get home and parked in my driveway for the day. That night I went to start the bike and again same issue. It started but struggled. At first seemed like it was not getting any gas. I removed the fuel pump and tied it into the battery directly to make sure it was working. It was. When I put the fuel pump back and hooked the relay back up the fuel pump seemed to come on sometimes and sometimes not. SO maybe the relay? Today I went to start the bike. It had rained over night but the bike was dry this morning. Again it started but the RPM gauge was not working. I had to keep the throttle open a bit until the bike warmed up and then all of a sudden the RMP needle kicked in and the bike revved with no problem. I drove for approx. 30 mins with very little trouble. When I shifted down at stop lights if I let the throttle back the RMP needle dropped to just below 1000rpm and the bike stalled. Started up no problem. Returned home parked in the driveway. Left it for 5mins and tried to start it again. Same issue. RPM needle does not move and bike seems to be struggling to stay running.
Gas tank is 3/4 fuel. Oil level is good. Battery is new as of April.

Bad relay maybe? Bad fuse maybe? Very new at this and have no idea.

Thanks

 

If the pump is anything like the ones on the later models, (2nd gen) then it should only run when it needs to. It stops pumping when it detects that the line is full due to fuel pushing back on the diaphragm. Could be something that got wet and doesn't want to work right. Coil or CDI maybe?

 

Check your trigger connections to your coils. One coil fires two cylinders. I had same symptoms after restoring my 83 last summer. Check corrosion on the tabs on the coils, and check the connector on the wire. After cleaning the contacts, mine ran fine, then started doing it again after several months, turned out to be a fatigued blue wire. The connector has hanging on one or two strands!
Take tank off and turn it 180 degrees, and let it rest on the tail. (Use a bungee cord to keep it from slipping). Start it, then start poking at the wires, if RPM jump, then you have found it.

 

I will try that this afternoon. Thanks

 

So I replaced both coils and Spark plugs. Bike starts but no spark to one coil. coil on the right side had spark from the two spark plugs found near front of bike but coil on the left has no spark from plugs near center. Any thoughts? CDI?

 

CDI units in the tail section, just in front of the tail light, check connectors and wiring there.

 

SO I traced all the wires back to 3 units just infront of the tail light. The blue from one coil leads to one unit while the yellow leads to the other. I believe they are CDI ignitor boxes. One had a bright yellow sticker while the other has a bright red one. When I reverse them and hook the yellow sticker box up to the coil that is not sparking it sparks so this leads me to believe the red sticker box is dead. Make sense? Hopefully I am on the right track here.

 

I have seen several posts on guys that have repaired these. Apparently, there are bad solder joints on the little PC board.

Just Google "motorcycle cdi unit repair", worth a try.

 

Inspect the rubber seal at the bottom of the fuel filler cap. With a bad, cracked, broken seal rainwater can get into the fuel tank in heavy rains.