Just bought an '88 K100 brought a friend with me and test drove it and everything was fine, got home and on the 2 rides it’s been on it’s died and doesn’t always start back up, im replacing the fuel injectors soon because it had some bad gas in it and they looked rough. any suggestions or help?

I would change the Fuel filter, Fuel lines. You can try to blow through the filter and see if it is constricted. Good to start with a good baseline on the expendables. Change oil and coolant also. Start fresh.  

Good luck on the project K1!
Bill

mmgee123 wrote:Just bought an 88’ K100 brought a friend with me and test drove it and everything was fine, got home and on the 2 rides it’s been on it’s died and doesn’t always start back up, im replacing the fuel injectors soon because it had some bad gas in it and they looked rough. any suggestions or help?

Howdy, and welkome to the forum. Next time you log in to the forum, how about going to Member's Introduction and, well, introducing yourself, and maybe tell us about your '88 K bike. It's right on the forum's main page, highlighted in red. It's also required, and the right thing to do before posting to other topics. And not on someone else's introduction. You'll find that we are mostly a helpful bunch. Thanks in advance.

Welcome too!

But beercause we are ol pharts too we forget what bike it is so its good to put your bike in your signature sos we can see what it is instead of passing beer time looking. Of course once K Pox hits you your signature ends up looking like mine so then it helps to put it in your post title.

Now I am thinking one of my Ks did that in 2021 and the problem was in the tank. Fuel pump in the tank has a filter basket, it was full of crap, plus the pump was not fully home in its mount and it would 'run out of fuel' about 70 miles after filling it up. I replaced everything in the tank, it solved all issues. I had the exact same issue with another K this year and again replaced everything in the tank and all issues cured. My K1100 is also showing similar issues so its getting the same treatment. Quite a few years back my RT did the same thing before I repalced everything in the tank too.

At this point I think its just one of the must do things when you get a K.

I did injectors in them all too, plus vacuum pipes, vacuum caps, external fuel lines and also crank case vent Z pipe.

None of its expensive stuff if you buy it right, ignore it though and it can leave you at the roadside.

Bad gas though is pointing to the tank fuel system.

Hey everyone i’m a new owner of a 1988 k100 i just got it home a few weeks ago and i’ve been seeming to have issues with the bike. It starts up perfectly with no choke even after not being started for days, but then as soon as i start going down the road (quarter mile-half a mile) it dies and doesn’t start back up. i just replaced the fuel injectors and previous owner said he’s just replaced the fuel pump, he did say it had some bad gas in it before i got it home, any ideas/advice?

But did he replace the fuel filter? And the filter basket under the pump.

I have had 3 Ks where the PO has done this stuff and done it wrong so I would go back in the tank and see whats happening there.

92KK 84WW Olaf wrote:But did he replace the fuel filter? And the filter basket under the pump.

I have had 3 Ks where the PO has done this stuff and done it wrong so I would go back in the tank and see whats happening there.

but would something bad in the fuel system just make it instantly die? i figured it’d sputter out some if it was something to do with fuel. but i do agree with you just because he said it was done doesn’t mean it was done right.

mmgee123 wrote:
but would something bad in the fuel system just make it instantly die?

According to your own description, it is not instantly dying; it takes it a quarter of a mile to die.

Laitch wrote:

mmgee123 wrote:
but would something bad in the fuel system just make it instantly die?

According to your own description, it is not instantly dying; it takes it a quarter of a mile to die.

that’s true sorry if i was vague, it rides like nothing is wrong for about a quarter to half a mile, and then shuts off instantly.

mmgee123 wrote:

92KK 84WW Olaf wrote:But did he replace the fuel filter? And the filter basket under the pump.

I have had 3 Ks where the PO has done this stuff and done it wrong so I would go back in the tank and see whats happening there.

but would something bad in the fuel system just make it instantly die? i figured it’d sputter out some if it was something to do with fuel. but i do agree with you just because he said it was done doesn’t mean it was done right.

The fuel pump sits in a vibration damper and in a plastic mount that has 5/6 bolts on it to clamp around the damper. This then has a small mesh filter basket that clips onto a recess in the vibration damper. The whole assembly clips into a holder inside the tank.

A few things can happen here:
1: Its not clipped in correctly and so runs out of fuel while the tank is half full, because the intake is above the fuel level.
2: The basket can be clogged up with fine grit, meaning fuel seeps in while the bike is parked, but at a much too slow rate for running and once the fuel in the basket is used, it cuts out due to lack of fuel.
3: The filter could be blocked with crap, the pump pumps through the filter to the injection rail.
4: The 'new' pump may actually be a dud used pump.
5: The electrical plug to the tank may be faulty.

1 2 and 3 have happened to me and with 1 [pump was loose inside the tank!] and 2 the cut out was instant and spluttering.

sounds like fuel tank filter to me

mmgee123 wrote:. . . it rides like nothing is wrong for about a quarter to half a mile, and then shuts off instantly.

Then what happens? Do you wait a few minutes and it will start again so you can run it back to home base?

92KK 84WW Olaf wrote:

mmgee123 wrote:

92KK 84WW Olaf wrote:But did he replace the fuel filter? And the filter basket under the pump.

I have had 3 Ks where the PO has done this stuff and done it wrong so I would go back in the tank and see whats happening there.

but would something bad in the fuel system just make it instantly die? i figured it’d sputter out some if it was something to do with fuel. but i do agree with you just because he said it was done doesn’t mean it was done right.

The fuel pump sits in a vibration damper and in a plastic mount that has 5/6 bolts on it to clamp around the damper. This then has a small mesh filter basket that clips onto a recess in the vibration damper. The whole assembly clips into a holder inside the tank.

A few things can happen here:
1: Its not clipped in correctly and so runs out of fuel while the tank is half full, because the intake is above the fuel level.
2: The basket can be clogged up with fine grit, meaning fuel seeps in while the bike is parked, but at a much too slow rate for running and once the fuel in the basket is used, it cuts out due to lack of fuel.
3: The filter could be blocked with crap, the pump pumps through the filter to the injection rail.
4: The 'new' pump may actually be a dud used pump.
5: The electrical plug to the tank may be faulty.

1 2 and 3 have happened to me and with 1 [pump was loose inside the tank!] and 2 the cut out was instant and spluttering.

i appreciate you going in depth, i’ll look into these thank you!

Laitch wrote:

mmgee123 wrote:. . . it rides like nothing is wrong for about a quarter to half a mile, and then shuts off instantly.

Then what happens? Do you wait a few minutes and it will start again so you can run it back to home base?

the 2 times it’s happened it hasn’t started till i pushed it back home lmao

mmgee123 wrote:the 2 times it’s happened it hasn’t started till i pushed it back home lmao

Gasoline can only pass through a mostly-blocked fuel filter—and/or fuel lines blocked with decaying passages—if it is not being pump at full pressure. At full pressure, fuel will become turbulent at the constricted openings and the engine will become fuel-starved. The result is the engine will start and run only on fuel that was already within the delivery hose and fuel rail before the pump started.  A two foot length of fuel hose can hold one ounce of fuel; that is the approximate amount of fuel contained in the fuel hose and rail on the delivery side of the clogged filter.

Let’s suppose a K100 2V engine gets around 42 miles per gallon. One ounce of fuel will run it 0.33 miles. That is approximately the distance you’re getting before the engine stalls. After the stall, the fuel line depressurizes in the time it takes you to walk it home, the fuel in the filter is able to flow again to fill the hose and rail, and you’re able to go another 0.33 miles when you start it again. Keep doing that 126 more times and you’ll have traveled almost 42 miles— give or take—depending on the richness of the fuel mixture, the condition of the electronic connections, your ability to work the throttle, clutch, and shifter efficiently, the direction of the wind, and the mood of the drivers you are obstructing. You’ll be able to shorten the number of times you need to start it to make the 42 mile goal if you walk in the direction of your goal when the engine stalls rather than walk it home. Either way you’re getting valuable quads, hamstrings and pectorals exercise.

Your problem might not be with a clogged fuel filter/clogs in decaying fuel lines within the tank; it could be just a faulty ground connection with an eerie predictability. I hope it would be one or the other because success is likely to get more expensive and complicated if it isn’t.

That is the end of this episode of Mountain Storytime.

Just so you know, it is possible to put the fuel filter in backwards. There is an arrow on it, the arrow should point away from the fuel pump.

As I said, I had 3 Ks did exactly what yours is doing. All due to issues in the tank.

92KK 84WW Olaf wrote:Just so you know, it is possible to put the fuel filter in backwards.

You’ll need two mirrors to do this: one affixed to an extension mount hooked around your neck so you can use it to view the other mirror that is mounted near the fuel tank opening and reflecting the image of the fuel filter inside the tank back to the mirror around your neck. At first, there could be confusion concerning which hand is your left and which is your right when viewed in the mirror, but you’ll adapt. All the leaning backward will build your abdominals and flexibility—another added benefit of do-it-yourself restoration.

Talking of mirrors...
I realised for the first time the other day that, although I am left-handed, I have always shaved with my right hand. This is because, in the mirror, it is my left hand, and it feels correct - just as if it is my left hand.
Anyone else suffer from this, this is a forum of oddballs after all?

Laitch wrote:

mmgee123 wrote:the 2 times it’s happened it hasn’t started till i pushed it back home lmao

Gasoline can only pass through a mostly-blocked fuel filter—and/or fuel lines blocked with decaying passages—if it is not being pump at full pressure. At full pressure, fuel will become turbulent at the constricted openings and the engine will become fuel-starved. The result is the engine will start and run only on fuel that was already within the delivery hose and fuel rail before the pump started.  A two foot length of fuel hose can hold one ounce of fuel; that is the approximate amount of fuel contained in the fuel hose and rail on the delivery side of the clogged filter.

Let’s suppose a K100 2V engine gets around 42 miles per gallon. One ounce of fuel will run it 0.33 miles. That is approximately the distance you’re getting before the engine stalls. After the stall, the fuel line depressurizes in the time it takes you to walk it home, the fuel in the filter is able to flow again to fill the hose and rail, and you’re able to go another 0.33 miles when you start it again. Keep doing that 126 more times and you’ll have traveled almost 42 miles— give or take—depending on the richness of the fuel mixture, the condition of the electronic connections, your ability to work the throttle, clutch, and shifter efficiently, the direction of the wind, and the mood of the drivers you are obstructing. You’ll be able to shorten the number of times you need to start it to make the 42 mile goal if you walk in the direction of your goal when the engine stalls rather than walk it home. Either way you’re getting valuable quads, hamstrings and pectorals exercise.

Your problem might not be with a clogged fuel filter/clogs in decaying fuel lines within the tank; it could be just a faulty ground connection with an eerie predictability. I hope it would be one or the other because success is likely to get more expensive and complicated if it isn’t.

That is the end of this episode of Mountain Storytime.

thank you man i really appreciate it!

92KK 84WW Olaf wrote:But did he replace the fuel filter? And the filter basket under the pump.

I have had 3 Ks where the PO has done this stuff and done it wrong so I would go back in the tank and see whats happening there.

 I agree with Olaf . How long had this bike sat before you got it ? If you want a reliable bike the best thing you can do is to replace the fuel delivery system and go through the ignition system cleaning all the contacts on everything and coating all the connections with dielectric grease .The problem you have sounds like fuel delivery to me .It may cost you some money up front but once you go through all this stuff that will be it and you'll have a good running reliable bike.I went through this same stuff with my 1988 K100RS  back in 2017 and since I got it sorted out she has run like a top.That was around 15,000 miles ago . The fact that the bike starts and runs ok for a half a block then dies tells me you have a motor that is worth the effort .

Topics merged (same question twice).