I bought this 85 k100rs with it not running. I went to test ride it before purchase and it died as soon as I got out of the driveway. The guy is a friend of mine so I know it ran decently before this. He purchased it not running where the issue was the fuel pump had gone bad. He replaced that and rode it for about a month probably before deciding to sell. Thinking the issue was only power to the fuel injectors and knowing I wanted to turn it into a café racer, I did some research that led me to the m-unit by motogadget. After hours of watching videos and tracing wire diagrams, I got it all wired for the ignition and start bare necessities. I'm pretty green when it comes to all things mechanical and electrical so this was probably too much to tackle but I did it and I can't turn back now. I replaced the injectors themselves from Mr injector. And tested those. Had power. I got everything wired up to test and... Nothing. Just a starter turning. Checked spark. No spark. Check continuity in plug wires. Checked resistance in coils. Everything good except 2&3 gave me high numbers. Replaced spark plugs, it was as simple as that. Gave me spark. However, still no ignition. Now, it was about 4 in the morning and I had to be up at 6 for work so I didn't do the most intelligent thing, but I sprayed starter fluid in the air box. What do you know? It fired up. It didn't stay running. I did get a video. I put new, fresh gas in to make sure that wasn't it. But that is as far as I've gotten and I'm not sure where to go. Does anyone have suggestions? I'll post a video

It runs when you supply fuel (starter fluid) looks like the fuel supply isn't working.

Last time with described symptoms on my 1984 K 100 it was faulty temperature sensor. Bike started but only with starter spray then died. After I replaced fuel temp sensor it started normally. Check the connection to fuel temp sensor, clean it and try to start.
Regards

daveyson wrote:It runs when you supply fuel (starter fluid) looks like the fuel supply isn't working.

I know the pump itself is working. Maybe not pumping enough? I'll check it out! Thanks!

nino wrote:Last time with described symptoms on my 1984 K 100 it was faulty temperature sensor. Bike started but only with starter spray then died. After I replaced fuel temp sensor it started normally. Check the connection to fuel temp sensor, clean it and try to start.
Regards

Oh the fuel temp sensor? Didn't know it had one . Haha I will research, inspect, and let you know my findings!

Built4comfort wrote:

nino wrote:Last time with described symptoms on my 1984 K 100 it was faulty temperature sensor. Bike started but only with starter spray then died. After I replaced fuel temp sensor it started normally. Check the connection to fuel temp sensor, clean it and try to start.
Regards

Oh the fuel temp sensor? Didn't know it had one . Haha I will research, inspect, and let you know my findings!

Ah! Did some searching on the net just now. Saw a post that you were in, actually! The water coolant temperature sensor! I will check that out later on. 

It is worth noting that when I got the bike, the ground strap looked... Like it had caught fire at some point? I see no damage or marks to indicate the bike had caught on fire but could that be the underlying issue? The sensor might be good but the earth ground for the frame/engine is bad?

Have you checked out the trouble shooting guide:

http://www.kforum-tech.com/electrical/EFI/bike-wont-start-EN.htm

Mike

If that sensor is out of 12 V no fuel at all. So check the connectivity

mike d wrote:Have you checked out the trouble shooting guide:

http://www.kforum-tech.com/electrical/EFI/bike-wont-start-EN.htm

Mike

I have not. I'll have to follow those tomorrow. When I go to work on it more. Thank you!!

nino wrote:If that sensor is out of 12 V no fuel at all. So check the connectivity

Will do! Thank you!

So I have narrowed it to the fuel pump. The coolant sensor was also a problem but I bypassed it for now. I ordered one and it is on the way. I pressure test the fuel delivery system and only got 6psi on the gauge. Me thinks I've found the issue. I'm going to take it apart, clean it, put it back together and see what I get.

I think I found the culprit. Simply no fuel pressure because of this booger. I suppose I should have checked the fuel pump closely when I first got it. The fuel filter is also toast. So I'm gonna get a new filter and hose tomorrow and give it another shot!

Make sure to use the correct submersible fuel hose for replacement - it can be quite expensive!

Quantum Flex Hose is submersible and cheap.https://www.ebay.com.au/itm/QFS-8mm-8mm-160mm-Corrugated-PTFE-Flexible-Fuel-Pump-Hose-Line-E85-Gas-Clamps/382376394058?hash=item590768bd4a:g:-q4AAOSwdyxe1oab
Regards Martin.

So that set me off looking for similar products on ebay.uk and Motorworks are still the cheapest!

chris846 wrote:Make sure to use the correct submersible fuel hose for replacement - it can be quite expensive!

Yup! Not quite sure what he was thinking. The hose had the biggest kink in it too so he didn't even set it up properly.

MartinW wrote:Quantum Flex Hose is submersible and cheap.https://www.ebay.com.au/itm/QFS-8mm-8mm-160mm-Corrugated-PTFE-Flexible-Fuel-Pump-Hose-Line-E85-Gas-Clamps/382376394058?hash=item590768bd4a:g:-q4AAOSwdyxe1oab
Regards Martin.

I'll check it out! Thanks!!

Dai wrote:So that set me off looking for similar products on ebay.uk and Motorworks are still the cheapest!

I'm glad I was able to help!

Bargain a few of us have just purchased Quantum fuel pump mounting kits. The kit consists of the rubber damper the plastic damper mount, filter basket,  flex hose, fuel filter, pump electrical crimp terminals, terminal boots and two cable ties. The whole kit was $55.00 Au shipped even cheaper in the US. A couple of more mates are now wanting to purchase the kits but I can't seem to find them online any more. They have pumps and filter baskets and flex hose in various lengths but no kits that I can find. The part number on the box is HFP-K437. We have fitted one part kit damper, mount and filter basket, the quality seems good and it fitted with no problems. I'll take some pictures later today and do a separate post.
Regards Martin.

MartinW wrote:Bargain a few of us have just purchased Quantum fuel pump mounting kits. The kit consists of the rubber damper the plastic damper mount, filter basket,  flex hose, fuel filter, pump electrical crimp terminals, terminal boots and two cable ties. The whole kit was $55.00 Au shipped even cheaper in the US. A couple of more mates are now wanting to purchase the kits but I can't seem to find them online any more. They have pumps and filter baskets and flex hose in various lengths but no kits that I can find. The part number on the box is HFP-K437. We have fitted one part kit damper, mount and filter basket, the quality seems good and it fitted with no problems. I'll take some pictures later today and do a separate post.
Regards Martin.

I am going to check this out for sure! For now, I just got some submersible hose and a new fuel filter and that seemed to do the trick! Thanks for all your advice!