Possible bad earth?

[GazKent]

Hello

 

Posted this on VFRWorld and it was suggested that I may have better luck here....

 

I have a 2002 VFR Vtec 800 which has just started having some very strange problems, I won't go into them all at the moment but I am suspecting a bad earth, if I disconnect the fuel pump I do have voltage on the earth and it will pass around 1/4 of an amp if connected to the bike frame, I am trying to trace the other end of the fuel pump earth and have read somewhere that there is an earth block in the wiring harness somewhere near the battery, can anyone confirm this? I have found the one at the front near the ABS electronics but this is not the end point of the fuel pump earth.

 

And after a request for more information....

 

Many problems (which was why I didn't list them) intermittent but when it is happening the fuel pump continues to run when you turn the ignition on but slower than usual (i.e. does not stop after about 3 seconds) , I measured the current when it is running like this and the pump is drawing less than usual (cannot remember the exact figues) but there is more current than usual flowing in total from the battery and I am not sure where it is going! Also, the bike will start but will stop if you turn on the lights or even operate the brake light, I did take the common bus connector off of the earth block that I found at the front but the earth from the pump is still connected to ground so I thought that there may be another common earth (as the one I read about near the battery), I ran a separate feed to the fuel pump (new wire from the pump relay to the pump and a new wire straight to earth) pump then ran at normal speed but I was getting a low (about 8 volts I think) on the original pump earth, when I measured the current I was getting about 1/4 amp from the pump earth to the bike earth. With all these issues I thought a possible cause was a bad earth so am trying to find the other end of the pump earth and go from there.
So as far as you know is there not another common earth block on my VFR? (mine is a 2002 Vtec with ABS which I believe makes it 6th gen?)
 

Once again, please let me know if more information is needed, any help appreciated

 

Thanks

[Grum]

Bonjour GazKent.

 

Suspect you are seeing some nasty voltage drop somewhere. Assume your Battery is charged and healthy and terminals are clean and tight?

 

First thing I'd check is the Main Blue Connector toward the front left side of the bike. This major connector has caused many issues for the EFI system in the past. It can cause severe voltage drop for the Main EFI power being the Black/White wire (beyond the Engine Stop Relay, ESR) and includes your Fuel Pump. This power comes in on the bottom wire of the Blue connector (see attached), being the Red/White wire then the Black/Pink wire which goes to the ESR. It goes back out again from the ESR to the ECM and other stuff via the Black/White wire through the Blue connector, so make sure that all the wires and connections look good at the Blue Connector.

See attached picture below an example of burnt connections in the Blue connector.

 

You need to be sure that you have a solid 12v at the ESR while probing the Black/White wire with Ignition to ON and Kill Switch to RUN. (Clip your voltmeter Black lead to Battery Neg terminal and Red lead to the Black/White wire at the base of the ESR.)

 

There is also a modification to the Green earth wire of the blue connector you can do by adding a good additional ground wire to it, typically if you are having headlight issues and buzzing relays the Green earth wire is the cause.

 

Your Fuel Pump Ground according to wiring diagram is most likely one of the grounds located at the rear of the fuel tank frame ground stud.(see Attached)

 

Also closely inspect your Main Fuse B 30amp and its wiring (see attached), this is the main power source for ALL your EFI stuff, it can suffer from heat stress and high resistance joints, causing voltage drop.

 

- Along with all your issues, what is your Fi Light (MIL) doing? Is it fully On when you turn on your ignition or flashing or doesn't come on at all?

 

- Is there any non standard wiring added to your bike?

 

NOTE - When checking any Earth/Ground wires. Have one meter lead on the Battery Negative Terminal (Not just frame of the bike) and the other lead on the actual wire, with your meter on the lowest Ohms range you should be seeing virtual ZERO ohms i.e a dead short situation.

 

Check the above and answer the questions mentioned, then we can get to some more targeted checking.

Cheers.

 

 

 

[GazKent]

Hi

 

Thank you very much for taking time to reply, I had already checked the blue connector (and many others!) and also the common earth towards the front left of the bike which all seemed fine, after much poking, prodding and swearing I finally found the other common ground that I have seen talked about, this is between the bike frame and the engine behind the coolant reservoir, this did have one burnt pin, I cut this out and bodged all the wires together and all seemed ok! I have now soldered all of these together and taped them back up, I am attaching a couple of pics in the hope that this may help someone else.  Just for info, the fuel pump ground also ran to this well hidden connector and another wire (from the burnt out pin I think) went to the ground point you talked about.

Once again, thanks for taking the time to reply.

[Grum]

18 hours ago, GazKent said:

Hi

 

Thank you very much for taking time to reply, I had already checked the blue connector (and many others!) and also the common earth towards the front left of the bike which all seemed fine, after much poking, prodding and swearing I finally found the other common ground that I have seen talked about, this is between the bike frame and the engine behind the coolant reservoir, this did have one burnt pin, I cut this out and bodged all the wires together and all seemed ok! I have now soldered all of these together and taped them back up, I am attaching a couple of pics in the hope that this may help someone else.  Just for info, the fuel pump ground also ran to this well hidden connector and another wire (from the burnt out pin I think) went to the ground point you talked about.

Once again, thanks for taking the time to reply.

 

Good find. I'm not familiar with this ground block on a 6gen, 5th gen yes, no mention in the Service Manual. Wonder if its only on the ABS versions for which I don't have a circuit diagram of.

 

- What does the other end of the connector look like, the buss bar, does it show burn marks as well?

- Does your bike also have the Grounds rear of the tank as per the diagram I posted for you?

- I'm guessing the burnt one was the actual Ground wire that feeds the others?

 

And you are correct, you shouldn't read any voltage on a Ground wire if its properly Grounded (with respect to ground) - Unfortunately I wasn't reading or interpreting your fault description properly, sorry about that.

 

- Is your bike now running with no issues?

 

Well, ya learn somethin new every day! 

Really pisses me off that Honda doesn't show where these Ground junction points are hidden. 

 

 

[Cogswell]

I've had good success at treating my connectors with Oxgard - keeps the corrosion down and helps conductivity.  It's no guarantee, but it seems to help.

 

 

[GazKent]

Hi

 

I downloaded the service manual (non ABS also) but that doesn't show either earth block, the other part of the connector, the bus that joins them all together looked fine.

Yes I do have the other ground points at the rear of the tank and one of these goes to the faulty earth block and there only appeared to be one bad pin but this was the one that connected to the visible earth point near the rear of the tank.

 

All seems fine at the moment, it was a bit of a nightmare as I had so many faults, I was getting MAP fault on the Fi light as well as sensor heater faults showing, it would sometimes stop when you turned the lights on or braked but not always, fuel pump running slow but it would also run fine sometimes after taking bits off, cleaning and putting them back! But then faulty again in the morning, guessing when it was cold and metal had contracted a bit, it was only when I found voltage on the pump ground that I decided a good place to start would be finding the other end of that wire which itself was a pain, I just felt as much of the harness as possible until I found a lump then untaped it and thankfully it was the earth block that had the other end of the pump ground!

 

Will see what it's like in the morning but I am hopeful that it is finally sorted and like you, am a bit pissed off that Honda build in "hidden" failure points without documenting them!

 

Cheers

[Grum]

Thanks for the follow up. Easy to see that with many Grounds not getting a good ground, that so many devices would be effected. Won't forget this one for a while.

 

Bottom line is you discovered a high resistance connection on the Ground side, a similar effect can be caused by a high resistance connection on the Power side.

 

Glad you have it sorted.

Enjoy your ride.

[Grum]

14 hours ago, Cogswell said:

I've had good success at treating my connectors with Oxgard - keeps the corrosion down and helps conductivity.  It's no guarantee, but it seems to help.

 

 

 

Thanks Cogswell.

I've generally just sprayed some CRC-2-26 as a switch or contact lube. Have just ordered a tube of Ox-gard on fleebay from a mob in Chicago called Pens N More, $10 AUD delivered, very happy with the price.

Cheers.