[Fergie2Fast]

Hey everybody I just picked up a k4 gsxr 1000 limited edition black. I got the bike on a good deal because when I picked it up it would idle great but wouldn't rev past 3000 rpm, still shifted through every gear fine and was rideable. Figured I could clean the fuel pump or adjust stva and it should solve the issue. The owner said that the tank was rusted before but he had it cleaned.

Had my dad try to ride it home but had to stop because it would only go about 50 mph and sounded horrible forcing it down the road with me in a car behind. After about 30 minutes of that we got AAA to tow it the rest of the way.

When we got back to the house the bike wouldn’t hold its idle. it starts up great to 1200 rpm then slowly drops rpm until it shuts off. Also if you touch the throttle it will shut off. Hitting ignition and holding the throttle will keep the bike on. I cleaned the fuel screen and did the internal filter bypass on the fuel pump after doing a flow test which solved the issue of not being able to rev past 3000 it can now rev to limiter but won’t idle and won’t rev at all unless done right when the bike starts which makes it practically unrideable. Stva is good butterflies are moving correctly but I still removed them. No FI lights or codes in dealer mode. Does anyone have any suggestions? Worried that the abuse on the highway did something.

 

[TwistedMister]

welp, rusted tank first thing you need to flush and clean entire fuel system.. tank, fuel pump, hoses, screens and filters, then fuel pressure regulator and injectors and injector screens..

start there, harbor fright has evaporust you can fill your tank with, 50/50 mix with water, tape off, 8-12 hours and its celan to the metal, geta quart of 99% rubbing alcohol, rinse the ER out with that, or rinse it with warm water then remove the water with the alcohol, reach in and towel off immediately to prevent flash rusting, or rinse with another quart of alcohol, drain, pat dry with towels, set in hot sun, should be good to go, go through each component and make sure its 100% clean//

TB's everything, rinse em good with carb cleaner off the bike pull the entire rail rebuild injectors or replace with new, if the bike was started with a rusty tank it's everywhere, regulator needs flushing, lines, everything

 

[Fergie2Fast]

Alright I really appreciate the information the tank was cleaned prior to me picking up the bike, looks great but fuel pump was filthy with rust and clearly hadn’t been cleaned. I’ll give the tank another cleaning with that evaporust stuff. Take off the throttle body and clean that up good along with the injectors and fuel rail. If I look down into the cylinders it looks like rust is caked on the valves I’ll try to get a swab down in there to clean the tops of them too then I’ll post an update.

 

[BillV]

Download the service manual if you haven't already. There's a procedure in it for measuring the fuel pump flow rate. Your main filter (not the strainer, though it could also be clogged) is almost certainly clogged with rust and needs to be replaced. You're not going to like the price. However "filty with rust" sounds like the entire pump may need to be replaced and you're really not going to like that price. Depending on the overall state of the bike, you might want to do some jury-rigged things that I generally recommend against. That would include an aftermarket pump motor (they're cheap but prone to fail) and either backflushing the filter or bypassing the filter and installing an external filter. There are many threads here about that. Here's a place to start.

The injectors have a fine screen on their inlets that can get clogged. They can be cleaned. But this generally shouldn't happen if the main filter in the pump is doing its job.

The bottom line here is you can't have any rust in the tank or it will cause problems.

 

[Fergie2Fast]

Update: Cleaned whole fuel system out still wasn’t staying running. Decided to order a new fuel pump which got here yesterday and she’s running like a dream. I appreciate all of the feedback.