Lost power over 3,500 RPM...but only when hot. That's weird.

[Snapey]

The first thing you need to do is make sure you have a good flow of fuel to the injectors & then worry about plugs or sensors. Get the pump out of the tank, clean/replace the tea bag, back flush the HP filter or better still do the bypass and wire the pressure regulator.

[Blubber]

As its heat related... check the coils for cracks.
Tell tale sign they are failing.

Had that on my gsx1100 the 1981 version. Cold drove like new... hot ( ca 15minutes) it ran like shit

[Tally]

Just a thought@ sa14 . In your opening statement you said it was very windy off the desert , have you checked the air filter isn't choked with sand, I,e low revs ,low air intake works well , high revs ,air starvation = rough running. 

[KiwiCol]

You've got that aftermarket spark advancer haven't you, now that'd make a difference when real hot I bet.   Just for giggles, how about disconnecting it for a bit & returning it to standard mode for a while & see how it goes?

[SA14]

Lots of good suggestions thanks. I'll get cracking and report back as I go.

A couple of things; the hum is more of a whistle now that I think of it. Quite high frequency. Not like the fuel pump, more like the engine fins themselves were vibrating. I've seen those rubber blocks between engine cooling fins and although highly unlikely I actually put my hand on the fins to see if that would stop it by chance but it didn't.

I'll check for cracks on the coils and the plug colour to see if that reveals anything. If they all look good I'll head into the tank. If that all looks good I'll start to suspect a sensor.

I've also done the PAIRS delete with a ball bearing. And if I get it again during the test ride I'll switch off the advance timing retard eliminator too. That would've been an easy test. Should've thought of that. Not sure what revs that operates up to but does 3,500 matchbin with that? The load symptom certainly does.

Great suggestions fellas!

Air filter was changed less than 1,000 km ago but I'll check it too.

[Snapey]

Do a fuel flow test.

[grog]

Start at the start. Flow and pressure test.

[SA14]

Start at the start. Flow and pressure test.

Do a fuel flow test.

I'll look up how to do a flow test but it runs fine when cold; we'll it did yesterday anyway. I may have to for another long ride around until it exhibits symptoms again and come home and do a test. Not sure what exactly a fuel test involves but I'm guessing when you turn the bike on it pushes fuel out at the maximum rate and I measure that?

How would I replicate a hot condition stress test without going out for a long ride on the freeway again? Or is that not needed because it'll show up on a cold test anyway?

The hot fault is what puzzles me. Then again I'm still very wide eyed when it comes to this bike. There's a lot of obvious stuff that hasn't cemented itself in as common sense yet. Should be able to start doing physical tests today after I get back from a few restos.

[SA14]

This was asked once before but not answered. It may have been answered in another thread but according to the manual I need to test the pump for flow for 30 seconds and get 1.2 litres. Can I just turn the power on and off until it measures 30 seconds or do I have to hook up to the loom and run the pump continuously for 30 seconds in one go for a proper test?

P.S. $88 for a tea bag strainer?!

[KiwiCol]

This thread talks about the flow rate (1.2L in 30 seconds) & pressure.  You can easy measure flow, but for pressure, you'll need a gauge in the line somewhere.

https://gsx1400owners.org/forum/index.php?topic=1474.0

[SA14]

Rang Suzuki and priced a new pump. There's one left in the country and the best "good guy" price he could do was about $700 and that's staff rates. Full retail was nearly $900. Tea bag filters are $90.

This one seems to still be available but of course ships from the US so who knows when it'd arrive. https://www.highflowfuel.com/i-35468028-quantum-255lph-performance-fuel-pump-w-regulator-for-suzuki-gsx-1400-2001-2008-replaces-15100-42f01.html

Haven't diagnosed it yet though. Suzuki said "sounds likely it's the fuel pump" although the 'hot temps only' is a bit puzzling to them too. I need to replicate it, ride it around for a while until it starts to do it again then head home immediately.

He also advised to be really careful twisting the throttle because if it comes good all of a sudden you're going to be looking for the nearest airport to land. Had to laugh because I didn't think about that and there I was giving it hand fulls of throttle in all gears...lol

To pay for this last post here's a few videos of before and after fuel pump replacement on a GSXR1000.

Before: [Note, no gravity fuel]

After [Note gravity fuel plus volume!]

Should mine come out like the after video or are GSXR1000s pushing way more fuel?

[Hooli]

I'm pretty sure the pump/filter/gubbins is identical in almost every injected Suzuki, it's just the swirl pot/metal bucket they sit in that changes between bikes. I know others have found second hand ones from gsxr600s etc fit that way.

[grog]

Just my thoughts, no expert. So many Suzuki wont rev posts. Gsxr, V strom, Busa. 90% is always HP filter not pump. Mine has never run as good since i did external filter mod. Costs bugger all, if it doesnt fix it, at least you know you have a good fuel supply. Then start looking for other probs. Proflow cleanable 30 micron i chose, Mahle replaceable 10 micron, same as BMW, Ducati use, its 50 mm diameter, might be harder to find a place for it, Proflow 40mm.It fits perfectly at rear tank mount, bracket ala Snapey or just foam wrap ala me. Tea bag filters are available e bay, a few dollars not $80. External mod works perfectly, gotta be better than spending hundreds.

[Eric GSX1400K3]

Baz, ive just put the Quantum hpfp in my 03.  No probs at all, dont waste your money on overpriced suzuki genuine parts.

I followed Andre's recommendation for the std quantum pump.  Works very well. Easy to assemble and fit.

[Snapey]

Rang Suzuki and priced a new pump. There's one left in the country and the best "good guy" price he could do was about $700 and that's staff rates. Full retail was nearly $900. Tea bag filters are $90.

Do me a favour and buy the $700 one but please give me first option to buy the one you're replacing. When the new one blocks up can we do the same deal or will you have realised that a simple 4mm hole and $40 filter was a good idea. BTW, I can do you as many tea bag filters as you like for a bargain $40 each.