F4i - Main Forum Main F4i discussion board

Fuel pump not priming

Thread Tools
 
Search this Thread
 
Old Mar 23, 2023 | 12:33 AM
  #1  
Bmk's Avatar
Bmk
Thread Starter
|
Junior Member
Joined: Mar 2023
Posts: 3
Likes: 0
Default Fuel pump not priming

I have a 2001 F4i and one day about 3-4 months ago I went for a ride and about 2 minutes into the ride my bike died like it ran out of fuel but the tank was full. Figured the pump was bad so I installed a brand new pump and nothing changed. I checked the fuel cut off relay and it’s fine and working. The pink wire coming from the zener diode reads 8.2v (I don’t know if it has to read exactly 9v or not but I feel like if the diode was bad it would read 0v or even the full 12v) the wires that connect to the fuel tank read 12v. I even check the tip sensor but it appears the owner before me already did a tip sensor delete basically permanently jumping the tip sensor. I’ve jumped both the old and new pumps and they both work just fine, at this point I don’t know what else it could be and if you have any ideas I would love to hear them
 
Reply
Old Mar 23, 2023 | 08:51 AM
  #2  
Al1040's Avatar
Welcome crew
Joined: Jan 2021
Posts: 2,568
Likes: 426
From: Preston, UK
Default

Welcome to the forum Bmk, it might be something as simple as the engine stop switch malfunctioning.
These are prone to causing the sort of problem that you are describing.
 
Reply
Old Mar 23, 2023 | 07:42 PM
  #3  
dannoxyz's Avatar
Senior Member
Joined: May 2011
Posts: 1,988
Likes: 439
From: Mesa, AZ
Default

Do you have spark?

Most likely not bad part anywhere, just loose/broken wire or corroded terminal in connector somewhere. Pull out meter and measure. This is 5-minute fix with meter, or less in many cases. Then do these tests.

1. Connect trickle-charger to battery.
2. Key ON
3. start/kill switch -> RUN
4. pull headlight fuse to prevent draining battery.

5. measure resistance between fuel-pump connector grn-wire terminal and chassis-ground, ohms = ???
6. measure resistance between engine-stop relay activation-coil red/wht wire to chassis-ground, (not bigger red/wht power wire), ohms = ???
7. measure resistance between fuel-pump relay activation-coil brn/blk wire to chassis-ground, key OFF then ON, ohms = ???

Next, let's trace flow of electricity to fuel-pump starting at battery...



8. measure FI fuse input-power to engine-stop relay big red/wht wire. Should always have power. Volts = ???
9. measure voltage at engine-stop relay blk activation wire from start/stop switch. Volts = ???
10. measure voltage at engine-stop relay output wire blk/wht, volts = ???
11. measure voltage at fuel-pump relay's inputs blk/wht (both of them), volts = ???
12. measure voltage at fuel-pump relay's output brn wire, key OFF then ON, volts = ???
13. measure voltage at fuel-pump connector, brn-wire terminal, key OFF then ON, volts = ???


Numbers will tell exactly where problem is. No need to replace perfectly-working parts with brand-new perfectly working parts.
 

Last edited by dannoxyz; Mar 25, 2023 at 02:39 PM.
Reply
Old Mar 25, 2023 | 10:11 AM
  #4  
Mpp's Avatar
Mpp
Junior Member
Joined: Mar 2022
Posts: 4
Likes: 1
From: Waterford
Default

Have you checked the 20 amp fuse outside the main fuse box ?
 
Reply
Old Mar 25, 2023 | 05:15 PM
  #5  
Bmk's Avatar
Bmk
Thread Starter
|
Junior Member
Joined: Mar 2023
Posts: 3
Likes: 0
Default

So I checked every wire and the brown wire at the relay shows no volts and the brown wire at the fuel pump connector also shows no volts all other wires show 12 or more volts I just don’t know how to follow the wire to see if it’s not connected somewhere
 
Reply
Old Mar 26, 2023 | 12:05 AM
  #6  
dannoxyz's Avatar
Senior Member
Joined: May 2011
Posts: 1,988
Likes: 439
From: Mesa, AZ
Default

If you have +12v on both blk/wht power-input wires on fuel-pump relay, but no output on brn wire, then some possibilities:

1. bad fuel-pump relay

2. no GRND from ECU on fuel-pump relay activation coil brn/blk wire. Could be broken wire. Did you measure ohms to chassis-ground??? Also measure that wire at ECU connector as well.

3. bad ECU

You're just ONE measurement from finding out what's wrong and fixing this (well, maybe two)...
 

Last edited by dannoxyz; Mar 26, 2023 at 09:49 PM.
Reply
Old Mar 26, 2023 | 07:46 PM
  #7  
Bmk's Avatar
Bmk
Thread Starter
|
Junior Member
Joined: Mar 2023
Posts: 3
Likes: 0
Default


Turned out to be 2 things 1 was that where the brown wire passes through the tank there was 9000 ohms of resistance so I took that green puddy stuff off and pretty much just pushed the wires down on the metal so they would make full contact and there was no more resistance. Then when I went to install the tank back on the bike the brown wire wasn't getting any power so I just jumped the power from the black and white wire to the brown wire on the relay and the fuel pump turned on. I’m pretty sure that means the relay went bad so I’m ordering a new one and hopefully it fixes my problems.
 
Reply
Old Mar 26, 2023 | 09:50 PM
  #8  
dannoxyz's Avatar
Senior Member
Joined: May 2011
Posts: 1,988
Likes: 439
From: Mesa, AZ
Default

OK...
 
Reply
Old Nov 22, 2025 | 08:59 AM
  #9  
dawesderek@gmail.com's Avatar
Junior Member
Joined: Nov 2025
Posts: 1
Likes: 0
Default Likely not the relay

Originally Posted by Bmk

Turned out to be 2 things 1 was that where the brown wire passes through the tank there was 9000 ohms of resistance so I took that green puddy stuff off and pretty much just pushed the wires down on the metal so they would make full contact and there was no more resistance. Then when I went to install the tank back on the bike the brown wire wasn't getting any power so I just jumped the power from the black and white wire to the brown wire on the relay and the fuel pump turned on. I’m pretty sure that means the relay went bad so I’m ordering a new one and hopefully it fixes my problems.
I’m having the same issue but the reason why it worked was because you bypassed the ground on the relay. your ecm is responsible for grounding relays and if it’s not wiring it’s possible your ecm is damaged all other things considered.

 
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
John R Deer
F4i - Main Forum
1
Mar 24, 2020 09:35 AM
reaper101
F4i - Main Forum
7
Jun 15, 2015 03:37 PM
kszx
CBR 1000RR
6
Jun 27, 2011 11:32 PM
iRIDE_F4i
F4i - Main Forum
8
May 1, 2011 11:09 PM
JC00
CBR 600RR
2
Jul 16, 2009 10:41 AM




All times are GMT -5. The time now is 05:21 PM.