Jump to content

Fuel pump issue


Easyrider

Recommended Posts

Need a little help from someone that has more knowledge then me this one has got me stumped. The bike is an 04 vfr800. The issue I’m having is the fuel pump won’t prime. The bike will turn over but I’m not getting any priming sound out of the fuel pump. I’ve seen other topics about this and have done some research but can’t seem to track it down. I’m getting 12v at all the relays and 12v at the fuel pump connection when it’s unplugged but when it’s Plugged into the fuel pump and I back probe the wires I’m getting 0v. Also when I connect the fuel pump directly to the battery with jumper wires I can get it to prime. It doesn’t make any sense to me that I have 12v at the end of the connection going into the fuel pump and I know the fuel pump is good because it kicks on when I hook it directly to the battery but it still won’t kick on under normal circumstances. Any help would be greatly appreciated. I’ve spent a week on it and still no luck. Thanks

Link to comment
Share on other sites

  • Member Contributer

At switch on the ECM provides the Ground to energize the Fuel Cut Relay for 2 seconds. So on the 12v side of the relay (Black/White wires)Yes you will see 12v all the time because you probably have your black meter lead on frame. However, to energize the relay the ECM controls the Ground to the relay via the Brown/Black wire.

 

Your comment:

" It doesn’t make any sense to me that I have 12v at the end of the connection going into the fuel pump and I know the fuel pump is good because it kicks on when I hook it directly to the battery but it still won’t kick on under normal circumstances. Any help would be greatly appreciated. I’ve spent a week on it and still no luck. Thanks"

 

This makes me think the Green wire of your Fuel Pump connector is NOT properly Grounded, make sure it has continuity (Zero Ohms) back to the Battery Negative terminal. Don't forget that at switch ON there will only be 12v for the Fuel Pump for approx 2 seconds.

 

Check this first. Let's know how you get on.

 

 

image.png

Link to comment
Share on other sites

I think your on to something. I’m reading 30ohms if I hook one end of the meter to the ground and the other to the negative on the battery. So new ground wire? Where do I run it from?the ecm to the frame? Sorry I’m an idiot when it comes to electrical stuff. Guess I’m going to learn a thing or two if I keep this bike.

Link to comment
Share on other sites

  • Member Contributer
27 minutes ago, Easyrider said:

I think your on to something. I’m reading 30ohms if I hook one end of the meter to the ground and the other to the negative on the battery. So new ground wire? Where do I run it from?the ecm to the frame? Sorry I’m an idiot when it comes to electrical stuff. Guess I’m going to learn a thing or two if I keep this bike.

Let me get this right! 

So you are saying from the Green wire of the Fuel Pump connector to the Neg battery terminal you see 30 ohms?  If so then that's the fault. You must see near Zero Ohms to Ground for this wire (Continuity).

 

To test the whole system. Make up a wire connected to the battery Negative and the other end neatly spliced into the Green wire of the Fuel Pump. Plug in the Fuel Pump connector. Switch ON, does it prime for 2 seconds? Can you start your bike?

Link to comment
Share on other sites

  • Member Contributer
3 minutes ago, Easyrider said:

I killed the battery trying to crank on it. I’ll give it a try when I get the battery charged up

Did you at least hear the Fuel Pump prime? Before you started cranking!

Link to comment
Share on other sites

Ok got the battery charged and tried to jump the ground with a alligator clip Directly to the negative on the battery still not priming. Tested the Ohms from the ground On the fuel pump connection to the negative on the Battery and got like .1 ohms so I must of been doing something wrong when I tested it yesterday. I took the tank completely off the bike so I could get a better look at where the wires were running to and while I had it off the bike I hooked up a battery With two jumper wires to the fuel pump connection and it kicked on and made the whining Sound like when it primes. So I went back and tested the brown fuel pump connection by probing the green wire and the brown wire Directly where the copper tabs from the fuel pump stab into it and got 12v for a few seconds after I turned the key on. I’m going in circles with this thing. It makes no sense to me. Is it not putting enough amps to run the fuel pump? 

Link to comment
Share on other sites

  • Member Contributer

Are you confident the Fuel Pump Green wire is now Grounded? 

 

Hang in there, you have at least confirmed the ECM and Fuel Pump are working correctly. Your problem should be a simple one!!!!

 

Try this.

- Remove the Fuel Cut Relay.

- Make up a jumper wire.

- Place the jumper link between any of the two Black/White wires and the Brown wire. NOT the BROWN/BLACK wire.

- Have the Fuel Pump Connected.

- Kill Switch to RUN.

- Ignition to ON

Do you hear the Fuel Pump run continuously ?

 

WARNING - DO NOT JUMPER THE BLACK/WHITE to the BROWN/BLACK WIRE You Could Destroy Your ECM.

Link to comment
Share on other sites

  • Member Contributer

The next thing I would check is if the terminals inside the fuel pump connectors are such that they guarantee a good connection, perhaps clean and tweak them so the connection is tight.

Link to comment
Share on other sites

  • Member Contributer
2 hours ago, raYzerman said:

The next thing I would check is if the terminals inside the fuel pump connectors are such that they guarantee a good connection, perhaps clean and tweak them so the connection is tight.

Great point. I've just assumed the OP with all his checking at the fuel pump connections would have checked this. His strange reading of 30ohms to ground of the Green wire has thrown me off track a little.

I am sure his issue will be a simple one as he has at least seen 12v at the Fuel Pump wiring for 2 seconds at switch on, meaning at least the ECM is working correctly.

Link to comment
Share on other sites

Thought it might be the wire connection so I cut it off and hard wired it to the fuel pump and it still won’t prime. With the wires disconnected from the fuel pump I get 12v but once I hook the wires up and test it I get between .5-1v. So does that mean that it’s grounding out inside the pump itself. If that’s the case then why does it prime when I jumper wire it directly from the battery. I appreciate the help. Without your advice I would be completely lost. Thanks

Link to comment
Share on other sites

  • Member Contributer

Ok so you've soldered the fuel pump wires to the pump connections. That isolates any bad connection scenario at the pump.

If you can operate the Fuel Pump from your battery direct then there's nothing wrong with the pump!

Just have a test wire connected to battery Positive and touch the other end carefully to the pump Brown wire terminal. Does the pump run? If yes that confirms the ground wire is ok. And your Brown wire could be the issue.

 

Just incase you have a faulty Fuel Cut Relay. Do the check previously mentioned regarding removing the Fuel Cut Relay and get back to us.

 

 

Link to comment
Share on other sites

Bad fuel cut relay. Did the jumper wire trick you mentioned early and it primed. When I was testing the relays A few days ago I must have been doing it wrong. Thanks for all of he help. Would it be alright if I temporarily left the jumper wire in until the new relay comes in the mail or would that burn up the pump. Nice weather and I just want to take a quick ride

Link to comment
Share on other sites

  • Member Contributer
21 minutes ago, Easyrider said:

Bad fuel cut relay. Did the jumper wire trick you mentioned early and it primed. When I was testing the relays A few days ago I must have been doing it wrong. Thanks for all of he help. Would it be alright if I temporarily left the jumper wire in until the new relay comes in the mail or would that burn up the pump. Nice weather and I just want to take a quick ride

At last, well done. Don't leave the jumper in.

Just locate your High Beam Relay. Take that and place it in the Fuel Cut Relay position.

Try it and get back to us. 

Link to comment
Share on other sites

Dam thought I had it. Tried the headlight relay in its place and I didn’t work. Only works when I use the paper clip trick. Really thought it was just a bad relay but I took it off the bike and used a 9v battery On it and I can hear it click. Is the bank angle sensor not allowing it to close the circuit. 

Link to comment
Share on other sites

  • Member Contributer
On 5/23/2020 at 11:27 AM, Easyrider said:

Dam thought I had it. Tried the headlight relay in its place and I didn’t work. Only works when I use the paper clip trick. Really thought it was just a bad relay but I took it off the bike and used a 9v battery On it and I can hear it click. Is the bank angle sensor not allowing it to close the circuit. 

M8. If you look at the drawing supplied you are only concerned with the top RH side. You should be able to see that if you have 12v at the Black/White wires of the Fuel Cut Relay that means the Engine Stop Relay is energized meaning the Bank Angle Sensor is working. Your "paper clip trick" would NOT work if the Bank Angle Sensor was faulty.

 

You seem to have established a problem at the FCR relay base connections!

 

Just to be sure, with Ignition to ON, Kill Switch to RUN, FCR removed, do you have solid 12v at BOTH Black/White wires at the FCR base? (Black meter lead to a KNOWN GOOD GROUND Or the Battery Neg terminal)

 

Have a GOOD look at the Fuel Cut Relay Base. Are all the connections Good?  Is the wiring Good?  Is the relay base connectors making Good contact with the Relay contacts? Do any of the spade connections on the relay base look wide/spread? Any evidence of heat stressed connectors? Have a good look at your original FCR are there any signs of corrosion or heat stress to any of the pins?

Do you see anything like the attached photos for the relay and relay base?

 

The "Paper clip trick" is purely acting as the relay contacts being energised closed, transferring 12v power from the Black/White wire to the Fuel Pump Brown wire. This confirms the continuity of the Brown wire to the Fuel Pump and your Green Fuel Pump wire is properly Grounded.

It only leaves the FCR Relay base connections that can cause your problem!

 

Keep us posted with what you find - Just as keen as you are to get your bike sorted.

 

P.S. For Info - Just hearing a Relay Click is not a conclusive test that the relay is OK. It still could have high resistance contacts. It is just an audible test to confirm the relay coil is being powered correctly. 

 

image.jpeg

image.jpeg

Link to comment
Share on other sites

  • 2 weeks later...
  • Member Contributer

Sent Easyrider a PM to see how he was progressing with his bike issues. Below is his response. The bottom line was a Faulty Fuel Cut Relay.

 

"It was a bad fuel cut relay. When I was testing the relays I was leaving them on the bike and back probing them and getting 12v. I finally realized that that’s not testing the relay It’s self that’s only testing the volts  going to the relay. Order one from eBay and when I put it on it fired right up. Thanks for your help in narrowing it down much appreciated. "

 

Baffles me as to why fitting his Hi Beam Relay to the Fuel Cut Relay position didn't sort out the Fuel Pump Issue!!

 

Good news is, his bike is going.

Link to comment
Share on other sites

  • 1 month later...
  • 2 months later...
  • Member Contributer

Fuel cut relay was just red-herring. Most likely some wiring got jiggled in fuel-pump circuit during swap and this fixed issue.

Why replacing relays didn't work is because fuel-cut relay was working perfectly fine. Replacing perfectly-working parts with brand-new perfectly working parts changes nothing and bike still won't run! Need to test every component and piece of wiring in circuit to determine what's actually bad before replacing. Swapping parts is not effective troubleshooting method because you end up with tonnes of extra brand-new spares to replace perfectly working parts; thus wasting tonnes of time and money. Issue in this case, is control-signal to activate relay wasn't present.

 

Order of operations to test is in this order (follow flow of electricity from source). 


1. power @ battery + terminal

2a. power going into ignition-switch

2b. power going into engine-stop relay

3. power going out of ignition-switch

4a. power going into engine stop switch

4b. engine going into bank-angle sensor

5. power going out of engine stop switch

6. power going into engine stop relay

7. power going out of engine stop relay

8. power going out of bank-angle sensor

9. power going into fuel cut relay

10. power going out of fuel cut relay

11. power going into fuel pump

 

Use multimeter and test voltage at EVERY point on circuit listed. ANY one of these points NOT having power will leave fuel-pump disconnected. Once you find that point, figure out WHY that point has no power. Higher upstream points have higher-priority, if it's not working there, EVERYTHING after it will be dead also. Also measure continuity to chassis-ground (ohms) :

 

12. bank angle sensor ground & chassis ground

13. fuel cut relay ground & chassis ground (2-sec with key ON)

14. fuel pump ground to chassis ground

 

Without proper 0-ohms ground for ALL above, fuel-pump will never activate. In my case, my bank angle sensor was stuck in leaned-over position and never allowed grounding of engine stop relay. Thus engine stop relay never activated and sent power to fuel-cut relay. Thus fuel-cut relay never activated and never sent power to fuel-pump.

 

image.png

Link to comment
Share on other sites

  • Member Contributer

Hi DannoXYZ.

Agree with your source to destination OR destination back to source approach for Power and Grounds. However, in this case items 1 to 12 can eliminated because a solid 12v was established at the Fuel Cut Relay socket. Also a solid Ground was eventually established for the fuel pump, and the ECM to FCR control ground was also confirmed eliminating items 13 and 14.

 

A shorting link across the FCR socket relay contacts would run the Fuel Pump. That basically left a faulty FCR or its socket. So I don't fully agree with your statement "Why replacing relays didn't work is because fuel-cut relay was working perfectly fine"

 

It would have taken forever stepping the OP through each of the suggested items, especially when he didn't appear to have a good grasp of the use of a multimeter, OR an understanding of the wiring, and as he states "Sorry I’m an idiot when it comes to electrical stuff". He also admitted he was Not checking the relay operation correctly.

 

We haven't heard back from the OP so we can only assume his bike is running ok since replacing the FCR back in May!

 

For trouble shooting purposes, to isolate a possible faulty relay, there is no issue at all in swapping a known good Hi Beam relay for example, with the ESR or FCR, as all four relays on the bike are the same type.

 

Another example of a dead Fuel Pump situation - So the first thing you do is connect two test wires Direct from the Battery to the Fuel Pump connections, the Pump does Not run. You've now diagnosed a dead Fuel Pump. There's no need of going through all the steps of 1 - 14 when a pump replacement fixes the issue.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...

Important Information

By using this site, you agree to our Privacy Policy.