Just throwing this out as a hypothetical...🤔

If the fuel tank outlet or petcock was restricted somehow, such as a gummed-up tube filter in the tank, could the lack of efficient fuel flow cause the pump to draw more amps in the attempt to keep up with the 100mph+ riding I'm doing every day???

Is it possible that could be causing brand new relays to melt down? The bike seems to be running fine right now for short hops below 4,000 RPM.



Topanga & Pacific Coast Highway (PCH) between Santa Monica and Malibu, CA

 

In a word, no.

 

Bummer. I was hoping I was on to something.😕

Back to the hypothetical drawing board, I guess. 🤓

 

Is the fuel pump you are using OEM? It would be interesting to know what the resistance is through the pump. You would need to remove the black cap so you could get your meter on the actual wires of the pump and not include the contacts. This pump is really just a fancy solenoid. The plunger acts on a diaphragm which moves the fuel through 2 one way valves.

 

Still working on the relay meltdown problem but I have a couple other questions: I just received a 4-pin to OBD-II adapter I ordered a few days ago to help with diagnostics on the F3. The item description said it is compatible with nearly all Honda motorcycles, but can you tell me where it connects? I have a good OBD-II code reader but unfortunately there's no instructions at all included with the adapter...

Does a '97 F3 even have a 4-pin on-board diagnostic connection that can be connected to an OBD-II via an adapter? 🤔

 

No, F3's are not OBD II compliant. I'm not sure it would have applied to them anyway since they are not fuel injected. OBD II was primarily for emissions and would tell you about knock sensors and O2 sensors and things along those lines. F3's have none of those.

 

Well I guess it's a good thing that Amazon Prime members get free returns! I'll send it back this weekend.

Thanks for posting a response.

 

OMG! KMN! Just put a brand new cutoff relay on yesterday and bike ran fine around town; charging voltage/everything seemed fine. Put in a brand new battery over the weekend hoping that might have been the problem...

Got on the freeway this morning and the new relay melted down within 16-miles @ 65mph. Had a spare relay and put it on - the bike made it about a mile on surface streets. 🤨 Put another brand new relay on (3rd one today) and made it less than 3-miles. Now I'm sitting on the side of the road waiting for a tow truck and wondering wtf!?

I just don't get it but I want to work it out. Where do I need to start?

 

Here's what I got this morning for voltage readings @ the 1997 600F3 fuel pump relay wiring harness, no cutoff relay installed:

Key on, ignition switch on (battery a little low from lack of charging - headlight & lights on)...

Blue wire w/yellow stripe: 11.8v
Black wire w/white stripe: 11.8v
Black wire w/blue stripe: .07v

I'm pretty sure one of those wires is a ground and should not have any voltage whatsoever in it.

Question #1: If a ground wire is back-feeding voltage into the cutoff relay could that cause a meltdown?
Question #2: Which wire at the fuel pump cutoff relay harness is the ground?

Question #3: If the pump relay is not present to complete a circuit should two of the wires both be getting ~12v?

Please Help!!! 🙏🥺

 

I'm leaning towards a connector or wiring corrosion drawing higher than designed current causing the relays to cook. I also found this in the service manual, maybe it'll help.