Good Morning from Dorset UK!
I have a K4 that I have bought recently. This bike belonged to a friend of mine, and I bought it after he has had issues with it.
Bit of a long story, but here goes.
He went for a ride, came back and it wouldnt start.
It went to a bike shop where it remained for 2 years.
At the bike shop they bypassed clutch and stand switch, removed after market immobiliser, then ran out of ideas and eventually left it outside his house.
It turns over(after rebuilding starter, must have turned it over till it gave in)
The check light is on, it would appear there is no negative output from the ECU, can get 12v live to frame on some reduced voltage components, but nothing when on the specific wires are tested. Also the battery was bulged and one cell blown out.
The fuel pump will operate but not at full speed.
I have decided at this point to just replace the loom and ecu.
The problems I am getting is finding the parts. It would appear that there are 2 ecu types a big plug on 2 plug. Also finding the 2 plug loom is proving impossible (8 months so far) Could I change the loom and ecu together? also later 2 plug ecu's from factory immobilised bikes, they look the same, is the immobiliser in the ecu? I have seen tranponders, aerials and ecu bundles.
Can anyone here answer these questions or point me in the way of someone who can.
Matt.
Ayup, you've got the rarest one there!
K4 had the late ECU but no immobiliser as you've found out, they're also the rarest model of 14. I only know of 1 in the wild.
I believe the immobiliser is in the ECU, but you'll need the ariel thingy around the key for it to connect too with the later loom that has the wiring for it.
I think you'd be able to fit a K3 loom & ECU without issue as the only difference is the ECU plug. K2 is slightly different as they've got a headlight switch & no hazard lights so you'd need a RH switch gear too.
I've never actually heard of an ECU dying though, so I'd be surprised if that's the cause of the problems.
BTW, when you get it running. Reconnect the clutch switch before you ride it much, they trigger different ignition mapping for easier starting & tend to make the bike run crap on the road when bypassed.
PS, you'll get told an intro in the intro section is appreciated as it's part of the culture here.
Yes, as Hooli said, an intro and photos if possible always, appreciated. :onya:
As for advice listen to Hooli and the others, not great on electrics myself. :whatever:
However, Welcome the forum, all the same. :welcome: :cruisin: :welcome1:
I would send the ECU to an expert who rules before opting to change
Hey mate, yes an intro is always a good place to start. A good strong battery is key, plus xhwckiny all earth's. Ecu is pretty bulletproof, sounds to me like its not the ecu.
Plenty of help on here, im sure you'll get it sorted
wiring versus connections. years of humidity, vibrations, "breakdown investigators",passage of simple time, extreme temperatures above and below, and already in place - for believers - the demon that touches everything (not lucas here, of course)
However, ECU enjoys the methodology and manners of the Confucius system.
Welcome :grin: Matt :cheers:
There's plenty of brainy bike folk on here to assist you. Definitely "xhwckiny all the earth's" is advisable, but I think that needs a special, rare tool...the svdaqhxm :grin:
Sometimes the whole problem is a bad mass, I have put a 2nd battery cable to chassis
Gidday Matt, welcome aboard. So, do you have a new fully charged battery in there now? If yes, do you keep the bike on a tender to keep the battery fully charged seeing as how it's not running to charge it?
You say the fuel pump operates but not at full speed, the bike is never going to start unless you've got full pressure & flow. Have you personally checked the fuel pump for condition? There is a possibility the teabag filter if clogged or the internal HP filter is clogged. The pressure regulator has also been known to come off & cause a no start condition.
If it were me, I'd work on 1 thing at a time, confirm you're getting power to the starter & fuel pump etc then attack the fuel system, ensure it's all working as it should, replace / repair as necessary. Then confirm you're getting the flow to the injectors & they're working.
Go step by step through each system in turn, you'll find it alright. Like Hooli, I doubt the ecu just died after a ride & wouldn't start, but a fuel system issue is definitely on the cards in that scenario. either blocked hp filter or pressure relief valve has come off.
Good luck, keep us informed as how you're going with it.
Oops, I meant "checking all the earths" my bad :notworthy:
Any bike sitting for multiple years is always going to be an issue. Tat shop must have been very patient or useless. 🫣
You'll get plenty of advice from a wealth of knowledgeable guys who have usually had the issues you're dealing with and cured it with help from others in our wonderful community of dedicated GSX1400 owners.
Some even in English lol 😂.
I'd also check the age and condition of the tyres before you ride it after you've got it running once again.
G'day Matt and welcome to the nuthouse 👋👋
Quote from: GSXKING on Saturday, 24 January 2026, 08:53 AMSome even in English lol 😂.
Eric was just showing off his international linguistic abilities . . . :rofl2:
Quote from: KiwiCol on Saturday, 24 January 2026, 09:43 AMQuote from: GSXKING on Saturday, 24 January 2026, 08:53 AMSome even in English lol 😂.
Eric was just showing off his international linguistic abilities . . . :rofl2:
Oh yes Eric, I meant Eric lmfao 😂
Welcome Mate. A bit more info needed with your problem. It cranks over normally?Unless something mechanical has broken, either lacking spark or fuel, you need to know which. Fuel check is easy, a squirt of ether or carb cleaner in air box.Spark youll need a test plug.You can then go to next step👍
Quote from: Barbastro K6 on Saturday, 24 January 2026, 12:04 AM...the demon that touches everything (not lucas here, of course)
Let's call the culprit by name. Everyone needs to know so they can avoid him like the devil avoids holy water:
His name is Copper Worm.
A sneaky bastard who's allie is time. Don't give him the time he needs to do his thing. Otherwise you will get a desease that makes you scratch your head all the time.
Absence certainly lets the geckos, ants, most critters all run free, create damage.Wasps a problem here, nest everywhere. Humidity, moisture all create mainly electical faults. UK climate with salty roads would be a nightmare for me.
Wasps not much of a problem here. Got to know them well when clearing a "field" with a sickle in Spain. Felt like every meter a wasp nest. In my dreams, it was more like every 10 centimeters (lied, I don't dream about these shitters). Wasps are protected in Good Bad old Germany. Don't even slap at them when a Greeny is near.
BTW, using a sickle is fantastic exercise to get rid of SI-joint problems. Shovel and pick are great for managing back problems (romanian deadlifts are the cure to get rid of them once and for all).
Speaking of Romanian. Recently met a very fine Romanian female. Way too light for doing Romanian Deadlifts with her.
Quote from: grog on Saturday, 24 January 2026, 07:24 PMAbsence certainly lets the geckos, ants, most critters all run free, create damage.Wasps a problem here, nest everywhere. Humidity, moisture all create mainly electical faults. UK climate with salty roads would be a nightmare for me.
It most, certainly is. :sad: :imrgreen: