Fuel pump/ flow problem

[badger]

The bike is literally driving me fucking insane. 
Taken the fuel pump housing apart a million times. (Gsxr1000 k7 in a custom tank) Rebuilt with a new pump (walbro gss342) etc and I have perfect fuel flow. Ride it for 5 mins and I have a fucking trickle again. Tried wiring straight off the battery and it's the same. I'm beyond lost with fixing it. 2 months and I can't figure out what it's doing.

I've still got the internal regulator be it modified. Which could cause the problem but it seems to be doing what it should be. I can't find anything about the problem I'm having. I know I'm clutching at straws asking but any ideas would be massively appreciated!
Might just roll it into a bin at this point. 

Edited September 11, 2023 by badger

[Fredrik_Steen]

Are you loosing pressure after 5 minutes or what is the issue?

[Joseph]

I guess you've checked it but is your fuel tank venting enough ?

Edited September 11, 2023 by Joseph

[badger]

59 minutes ago, Joseph said:

I guess you've checked it but is your fuel tank venting enough ?

Vents fine. 

 

1 hour ago, Fredrik_Steen said:

Are you loosing pressure after 5 minutes or what is the issue?

Fuel flow drops of a cliff. Doesn't return until I've pulled the pump housing apart and started over. Short trip on the bike and it vanished again

[Arttu]

Sounds very much like you have some block on intake side of the pump. I once chased similar problem for quite long time before finding a displaced o-ring inside the tank side quick coupling.

[Fredrik_Steen]

8 hours ago, badger said:

Vents fine. 

 

Fuel flow drops of a cliff. Doesn't return until I've pulled the pump housing apart and started over. Short trip on the bike and it vanished again

It might be cavitation due to not enough flow into the pump / some kind of restriction. When the pump cool off it works again for some time.

[Gixer1460]

In-Tank pre pump filters!

You need them to protect the pump but they are usually tiny micron level filtration and once blocked its 'good nite Vienna'

They can't be cleaned to any great degree or return to useful service and from what i've seen / experienced with others - they aren't a servicable part so whole assembly needs replacing . . . . . . . who'd have thought a WHOLE pump assembly would be a service item, designed for failure!

[Joseph]

This bit ?

https://www.cmsnl.com/suzuki-gsxr1000-2007-k7-usa-e03_model34302/strainer_1542005h00/

[Gixer1460]

Well that's an improvement - actual replacements and a bit cheaper than Suzuki San charges - (this one from a GSXR1000 K1 2001)

STRAINER - (15420-24FB0) - £47.23 each

[badger]

1 hour ago, Gixer1460 said:

In-Tank pre pump filters!

You need them to protect the pump but they are usually tiny micron level filtration and once blocked its 'good nite Vienna'

They can't be cleaned to any great degree or return to useful service and from what i've seen / experienced with others - they aren't a servicable part so whole assembly needs replacing . . . . . . . who'd have thought a WHOLE pump assembly would be a service item, designed for failure!

You can swap out the pre pump filter. There is another on inside the plastic housing post pump and they're not replaceable and 350 odd quid! 

I have a new pre pump filter arriving tomorrow hopefully. The old one seems fine. There's no obvious blockage or restriction there. If I get a chance I'll pull it all to bits, take a bunch of pics. A few bits needed modifying to fit a bigger pump but that was done years ago without drama.

 

I've had it apart again tonight (typed everything before but didn't get time to finish before work) and I've wired up and led to the fuel pump so if the pump loses voltage I'll see. Idea off Wayne rotty! 

When I took it apart there was a split in one of the o rings. Which I think happened when I last put it in as I checked it before I pushed it together. It could have been the problem but I don't think so. After rebuilding it it put out the same amount of fuel in 2 secs as it did in 10 previous. 

I think something is unseating after been run for a little bit. I do think there's a separate wiring issue there too.

 

 

[Gixer1460]

27 minutes ago, badger said:

There is another on inside the plastic housing post pump and they're not replaceable and 350 odd quid! 

I thought there was another unserviceable one - how daft is that!

[badger]

Well....

Fitted the new seal. Pump had proper flow and after a few mins went back to shit. 

The new pre pump filter arrived (after the seal) and it wasn't quite the same. Different shape and not as deep which allowed the pump to move a bit. I've used a rubber stop (that came with the pump) to take up the space. It appears to have done the job. I'm not gonna temp faite but I've hit boost and it's not shit it's pants about it. Had proper pressure again when I got home. 

I'm still not sure exactly what the issue is/was. I don't know if the old filter was blocking the pump? It's clear but I wonder if it was getting squished on the bottom? Either way, for now it's working. Weird though that it was giving exactly the same flow after each test. If it was blocked I would have thought it would give varying results.

Everyone loves a photo. Black line is the flow I got when it was weird after 10 secs. Fuel line is what it's doing now after 5