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2008 Brute Force 750 fuel relay troubleshooting

17589 Views 5 Replies 4 Participants Last post by  ian.macmillan
Hi Folks!

This is my first post here - I was a fairly active member of a Suzuki forum, but recently traded my Suzuki for a 2008 Brute Force 750i Fuel injected.

The bike is a bit rough, the previous owned ran into fuel troubles and tried to fix it but really just made his situation worse. I've been doing a pile of searching and reading, but can't seem to get a straight answer on some things so I'm starting a thread here.

Here's the situation: The fuel pump doesn't run, and the fuel pump relay does not click. When I turn the key ahead I get a click from the ignition relay, but not the fuel relay. I've tried swapping the relays around, but that confirmed the fuel pump relay isn't bad. I also used a jumper wire in the fuel pump relay plug to force the fuel pump to run, and the bike will start if I do that. It seems like there's no signal coming from the ECU to engage the fuel pump relay. I've also made sure the rollover sensor is right side up, and shook it to ensure it wasn't stuck - which it wasn't.

Is there anything else that I should be looking at that would prevent the bike from running the fuel pump? Another thread mentioned removing the positive wire from battery for 10 minutes to reset any ECU codes, and someone else mentioned that low battery voltage will also prevent the ECU from allowing the bike to run. Is this true?

Really appreciate any help you can offer!

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Have you traced the fuel pump wire from the relay back to the ECU to check for any corrosion or brakes, if that wire truly goes to the ECU. Also the battery voltage thing seems like a pretty simple thing to double-check just to be safe
Dont forget to check all the wires going into the fuse block and also check for a blown fuse or coroded connections.

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Pull the fuse box out. Turn it over and inspect the wires. They will corrode and cause trouble. There is a thread on fuse box delete with waterproof inline fuses. Look into doing that. Also, that comment about low battery voltage is true. That bike is fuel injected, controlled by a computer. If it doesn't have the voltage it needs, all kinds of issues will come up.

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Thanks for the feedback.

Little update here: I think there might be a bad ground somewhere. I've replaced the fuel pump relay and plug with an aftermarket one and grounded it to the frame, and it's working correctly. Once I had the bike actually running, it would bog, backfire, and sputter any more than half throttle. I narrowed it down to the fuel pressure regulator being bad, so I replaced the whole pump assembly and that fixed that problem.

Now the bike will work fantastic for about 20 - 30 minutes, and then start to break down. If I let it sit and cool, it comes back around and works great again. My experience with cars and some reading tells me this is likely caused by weak spark from a bad ignition coil, so for the $60 I'll give it a shot and see if that solves the problem.

Put a new coil on the bike today and it's good as new.

Just for future reference for anyone searching for info, these were the specs and symptoms of my bike:

- 2008 Brute Force 750 EFI
- Any more than 1/2 throttle the bike would pop and backfire really badly
- Minimal power, it would barely move itself
- Got progressively worse as the bike got warmer

What fixed it:
- Removed the screen inside the fuel pump assembly (video for reference)

Can't believe the difference, the front wheels barely want to stay on the ground.
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