Hi guys

After my bike was assembled I took it out for a testride. It ran good, but suddenly it lost all power and was running very rough.
The electrics are fine and the engine cranks as I should. I have spark, fuelpressure, and the injectors squirt out fuel but I'm not sure it's enough?
When comparing videos on youtube it seems like their injectors spray out a decent amount of fuel, which mine don't. 
The fuel pump "sounds" fine, and i pulled off the fuelfilter hose where I saw there was pressure in the system.

When I press the linkage down on the throttle body so the butterflys close fully, the bike farts and coughs a little and is not far from starting.

What could be wrong? Not enough fuelpressure, maybe caused by the fuelfilter?

I appreciate any ideas 

Take the fuel filter out and try to blow through it in the direction of flow.

Collapsing fuel line and fuel return line can cause problems. It normally occurs where the lines enter and exit the tank. On some model Bricks it can be hard to see the kinked lines and even pulling the tank back sometimes won't reveal it. The kinks will sometimes restore themselves as the tank is pulled back. Non OEM return hose is very susceptible to this.
Regards Martin.

I recall riding up to a high altitude, from where I normally rode, on an old four stroke Kwacka back in the late '70s. The bike was bogging a bit so I took out the air filter thinking I'd lean it out enough and slammed the seat shut. Didn't I also place my summer-weight gloves under there on top of the airbox opening when closing the seat?! I went perhaps a mile or so before the bike began to stumble and run really rough. I was stumpified by the side of the road for a coupla newby minutes. Raising the seat and unblocking the air's path brought me back to reality and learning. Maybe an abandoned mouse nest has moved closer to the inner workings since it appears (from your avatar, at least) that you've not got an air intake horn attached to the airbox? All things considered.

Well, I did change the fuellines to non OEM! But I can't seem to find out how a fuel line can collapse when it is under pressure, not vacuum?

Fuel pourers out the filter no problem, and it seems okay but when I shake it, it rattles like the stuff inside it is loose.. Problem?

Yes the intake pipe thing is attached. The bike have been apart and everything is so clean you can put your tongue on it. So definitely no mouse nest!   

Maybe too much fuel in system. What happened to me few days ago? Somehow I broke ground wire of temperature sensor which sits under the tank. Tiny brown wire was broken after removing fuel tank.
In the middle of the city bike stopped, sudenly a lot of petrol smell around and no restart chance any more. It started only with removed fuel pump fuse but only for few seconds.
Check the wires. Just thought

nino wrote:Maybe too much fuel in system. What happened to me few days ago? Somehow I broke ground wire of temperature sensor which sits under the tank. Tiny brown wire was broken after removing fuel tank.
In the middle of the city bike stopped, sudenly a lot of petrol smell around and no restart chance any more. It started only with removed fuel pump fuse but only for few seconds.
Check the wires. Just thought

I don't think there is "too much fuel in the system", rather not enough pressure.

When I first assembled the bike, I switched the two hoses from the tank which may have resulted in pressure the wrong way around in the fuel pressure regulator.. I switched them back to the right position when I found out, and the bike started. (Right before my testride failure) 

Maybe the FPR could be damaged by pressure from the wrong way?

Bike would start with few drops of fuel, not for long of course. Can you measure fuel pressure 2,5 bar, or 36 psi
I dont believe that regulator was damaged because of wrong connection

I don't hope so, and I don't have the equipment to measure fuelpressure unfortunately.. I just read on a forum that I can check the the FPR by pulling off the fuel returnline, and fuel should poure out when I crank the engine.

New update: I changed the fuelfilter and after many hours research I found a small "trick". Squeeze the fuel returnline and see what happens.. It fired right up! Now the bike idles but won't take throttle. The plugs look alright, I think? It had only idleed for about 2 min before this picture was taken.

Does this mean the FPR is dead? to me it sounds like not enough fuelpressure, since squeezing the returnline should make more pressure in the system.

Any suggestions?

See post #3. Do you have fuel coming out off the vacuum supply line to the FPR?
Regards Martin.

MartinW wrote:See post #3. Do you have fuel coming out off the vacuum supply line to the FPR?
Regards Martin.

Nope, nothing in the vacuum hose

I'd like to add, when I fitted the fuelfilter I cranked the engine with only one hose attached to the filter, and fuel poured out in a pretty strong flow.

See post #3.

Yes I have read it, and no lines are kinked. But as I said, the bike actually starts when I squeeze and kink the return line a little.

It is possible that the return line has delaminated and when you squeeze the line you are partially opening the line. When was the line last replaced and was it replaced with a OEM line or just a piece of aftermarket hose.
Regards martin.

I replaced the returnline when I assembled the bike (before the testride where the bike stalled). It rode perfect until it didn't. The new hose is a lot softer to be honest, and it is not OEM.
Are the return line really under pressure? Shouldn't it be free flow since it is after the FPR?

Non OEM lines have a tendency to kink where they go into the tank, and it's hard to see if they are kinking. If the rubber is soft it's probably kinking. The OEM lines have preformed bends which don't kink over. You could try disconnecting the return line and running it to another container. If running non OEM lines it is advisable to use one of these where it goes into the tank and put another hose clip below the Uni Coil to it sliding down.
Regards Martin.

MartinW wrote:Non OEM lines have a tendency to kink where they go into the tank, and it's hard to see if they are kinking. If the rubber is soft it's probably kinking. The OEM lines have preformed bends which don't kink over. You could try disconnecting the return line and running it to another container. If running non OEM lines it is advisable to use one of these where it goes into the tank and put another hose clip below the Uni Coil to it sliding down.
Regards Martin.

I see. I think you have been right all along. I was sure the return line wasn't kinked, but after moving and pushing the return line, behind the air filter the bike started to behave normal when pushing at the right spot! So right now I'm carefully changing to the old knackered one and then I have ordered a new oem fuelline 

Well, it wasn't a kink in the fuel line which is causing all the trouble.. I changed back to the old OEM and the bike still won't take throttle.

Are you sure the old one isn't stuffed as well? Unclip the tank and move it back until you can see both the supply line and the return line. Visually confirm the hoses have no kinks where they go into the tank and try to start the bike. Are all the fuel hoses of the correct rating for use with EFI?

From your post #10, I think you might be right about the FPR. As you say, squeezing the return line will increase pressure in the system. (You're right about normally no pressure in the return line.) 
Pretty hard to regulate to 36psi by manual squeezing, though.

A new fuel pressure regulator will not be cheap, so I'd be looking for someone who can loan you one to try first, or someone who can loan you a pressure gauge. 

Your post #1 also says there is not much flow from the injectors compared to youtube videos. Also suggests low pressure.

I think you won't get any further intil you know what the fuel pressure is.

Good luck,
Bill

MartinW:
Well the old return line I put back on is rock hard, and does not have any kinks when mounted. I checked that, but to be honest I did not blow through it before mounting.. 
The hose from tank to fuelrail (supply hose) is straight with no kinks (still a new soft hose, and I have no specs on it).
The hose from fuelrail to FPR has no kinks only the original bends and it is still one of the old hard ones. I even tried switching back to the old vacuum hose as well..
I might try to wiggle everything a to get it started again, but unfortunately my bike is not on my home address..

Inian036:
Yep, I'm pretty sure it is something about low fuel pressure.. I will look for at gauge to measure what pressure the fuel system is on. Yes it is pretty hard to squeeze then line to feed the system 36 psi 
The bike would start and take throttle when I squeezed the line! It ran like crap, but it works and actually it could still idle when I released pressure on the hose.



I really appreciate you answers guys 

It is important that the fuel lines are rated for EFI and ethanol SAE 30 R10 for submersible  in tank lines and SAE J30R 14T2 for external lines or their equivalent. It is also important that you use EFI rated hose clips especially in the tank. Worm drive clips can delaminate the hose. As per Indies advice you need to test the FPR, the gauges and fittings aren't that expensive and can be bought as a kit or cobbled together from a gauge and appropriate hose fittings. Mine is made out of an old regulator gauge and bits and pieces.
Regards Martin.

The Lines inside the tank are the original lines. Will go buy some proper fuel lines and this pressure gauge.
https://www.biltema.dk/bil---mc/bilvarktoj/motorvarktoj/brandstoftrykmalere/brandstoftrykmaler-2000016980

The lines are 8mm internal diameter right?

If you buy a gauge it should go to at least 80 PSI and the hose on your proposed gauge by might not hold the pressure and should be clamped at all joints. You will also need a "T" and the lines are 8mm or 5/16".
Regards Martin.

Okay I bought a gauge today which measures 160 PSI. I will check the pressure in the system in the weekend when I have the time for it. Can I check the pump with the gauge as well? I'm considering to connect it directly to the pump so I can see if it pumps with 65 PSI which it is supposed to.

I'm also considering buying and adjustable FPR because its cheaper.

You can check both the pump and the FPR.
Regards Martin.

So today I fitted the manometer, and fuel pressure seemed as it should. 2,5 bar when trying to start the bike normally so the fuel system seems to work as it should. When I squeezed the return line to start the bike, fuelpressure was up to 7,5 bar which is waaay to much, but it would still run and take some throttle.

Now I'm considering taking it to a shop who can look for the problem. I have checked for an air leak at the Z-hose and also around the throttle bodies, but I couldn't find any. I'm running out of ideas.. 

Tommy add your moto's year to your profile info so we do not have to guess what you are working on

What is the situation with the petrol tank vent and water/rain drain tubing nipples under the tank?

the forward nipple is the tank vent- is this clear with a hose attached to it or do you have air accumulator cup ?
the rear is the rain drain- a hose attached running down along the back of right foot-peg plate

this thread will explain petrol vents and emissions tubing on engine block. Emissions tubing may or may not be on European moto version
Petrol tank vents etc...

Tommy2305 wrote: I'm running out of ideas. . .

Is there adequate spark from the coils? Are the injectors pulsing as they should?

volador wrote:Tommy add your moto's year to your profile info so we do not have to guess what you are working on

What is the situation with the petrol tank vent and water/rain drain tubing nipples under the tank?

the forward nipple is the tank vent- is this clear with a hose attached to it or do you have air accumulator cup ?
the rear is the rain drain- a hose attached running down along the back of right foot-peg plate

this thread will explain petrol vents and emissions tubing on engine block. Emissions tubing may or may not be on European moto version
Petrol tank vents etc...

Sorry I completely forgot to mention, but it is a 87 k100RT.
My tank looks different compared to the one you have posted. Mine have the feed and return line nipples, and on the rear i have 2 other nipples. I'm not sure what they are for but my guess is venting or overflow? There was a small catch cup underneath with a line attached. But no lines attached to those nipples.
I haven't blown through it with a air compressor but maybe I should? I have tried starting the bike with the fuel cap open of course. No luck

Laitch wrote:

Tommy2305 wrote: I'm running out of ideas. . .

Is there adequate spark from the coils? Are the injectors pulsing as they should?

I think the ignition system is okay, since the bike is able to start only with more fuelpressure, and I have spark on each sparkplug (new installed).  It didn't run great but sort of smooth with no misfire. I can hear the injectors are opening as they should when cranking the engine. I also pulled the injectors out from the block but still in the rail, and it seemed that the same amount of fuel came out of each injector when cranking the engine (not measured)

put the '1987' in your signature line

that pictured 1985 petrol tank is for illustration purposes of the tank vents and rain drain tubes

Have you checked the ECU connector plug is properly seated? Lift the seat and with flat blade screwdriver lever forward in the hole

Try to bypass the fuel pressure regulator- FPR

Connect the fuel injection rail outlet directly to petrol tank return

If you plan to change FPR search the interwebs for Beck Arnley 158-0073 can be found on Amazon

Beck Arnley 158-0073 

Is the throttle position switch properly adjusted?

Spark plugs Bosch X5DC or NGK D7EA with spark plug 5 KΩ wires ?

volador wrote:put the '1987' in your signature line

that pictured 1985 petrol tank is for illustration purposes of the tank vents and rain drain tubes

Have you checked the ECU connector plug is properly seated? Lift the seat and with flat blade screwdriver lever forward in the hole

Try to bypass the fuel pressure regulator- FPR

Connect the fuel injection rail outlet directly to petrol tank return

If you plan to change FPR search the interwebs for Beck Arnley 158-0073 can be found on Amazon

Beck Arnley 158-0073 

Is the throttle position switch properly adjusted?

My signature line are now updated
Since the fuelpressure is pretty much where it should be, I don't think the FPR is the problem. But I might check some of the connectors on the bike. Definitely the ECU but I have read just now that a bad coolant temp sensor could cause the ECU to not feed the bike enough fuel. 
Worth a try to give it some contact cleaner and measure the resistance.

I ran with the throttle position sensor disconnected when it broke down and I have tried starting it with and with out it being connected. Also tried it adjusted correctly and incorrectly. Still no luck.

bad temp sensor will indicate a cold engine to ECU and cause a 'rich' fuel situation

Measure resistance on temp sensor blade to body not blade to blade connection @20C approx 2500Ω

spark plugs Bosch X5DC or NGK D7EA with spark plug 5KΩ wires ?

check grounds under petrol tank and left foot-peg plate

volador wrote:bad temp sensor will indicate a cold engine to ECU and cause a 'rich' fuel situation

spark plugs Bosch X5DC or NGK D7EA with spark plug 5K Ω wires ?

Okay this is what I have read on another thread: " Other thing might be that your coolingwater temperature sensor gives a wrong signal and therefore the ECU gives too little fuel."

The plugs are NGK D7EA gapped correctly with the original wire leads. They were white the first time I pulled them out right after it broke down.

false temp sensor signal will give 'too' much fuel

check grounds under petrol tank and left foot-peg plate

volador wrote:false temp sensor signal will give 'too' much fuel

check grounds under petrol tank and left foot-peg plate

Will do 

Temp sensor on coolant 'T' into engine block ≅ 2.5KΩ @ 20°C

test pins 10 and 5 on the ECU connector plug under the seat. Flat blade screwdriver, 'lever forward' in the hole of the tooltray to loosen ECU connector plug

check the wires from Pin 10 & 5 of the fuel injection control unit plug for open or shorts

Pin 10 - violet/green
Pin 5- brown

Well I really appreciate the replys and contribution! I finally found the cause yesterday.

After hours of thoughts I pulled the injectors, and holy **** they were clogged up. All of them.. It might explain lean running and, and startup with extra fuelpressure. Much of the stuff from the injectors looked like excess paint since the stuff were black, and grey/white on the backside which make sense after I have painted the fuelrail 

I cleaned the injectors and this is what came out with a flush of all 4. Afterwards they were ultrasonic cleaned where even more stuff came out. I cleaned the fuelrail and returnlines and put the bike back together.
The bike ran well for around 4 minutes until one injector clogged up again..
So next step is doing it all over, but really get the fuelrail clean! At least only one injector clogged up, which means less stuff inside the fuelrail I guess.. 

Yeah, that would do it... 

Outstanding update

The petrol pump rubber vibration damper is in good condition?

Haven’t checked the vibration damping in the tank but it did nok strike me as ruined. I will check tomorrow when i have the time to work on the bike

Vibration damping looks fine. I have tried everything with these injectors and on of them keeps bugging.. Now I have had it and I will order a couple of brand new EV14 injectors from tills.de. 

https://www.tills.de/EV14-155ccn-konisch---sehr-feiner-spray-sehr-schnell-------the-best----.html

Money well spent!

Recommend 2 x Quick coupling petrol hose 8mm Tills.de

That would definitely be awesome to have those! it makes it really easy to remove the tank when working on the bike, but 120 euros.. I think I'll be okay with pulling the plug for the pump to release fuelpressure in the system 

The injectors in it self are pretty expensive I think, but nice to hear you think it is worth it. I really tried everything with the old ones, but they are cursed.
It looks like the Ev14 injectors really atomize the fuel.

 https://www.youtube.com/watch?v=f8cEG4wbWyk

Fuel injector cleaning

Test light dohickey

those injectors from the Alibaba?

I have read a lot about cleaning injectors and I have done what I could, that's why I'm trying backflushing them. They work for 5 minutes and then it clogs up. They are original Bosch injectors for a bmw E30 if I remember correct, and they have been a pain ever since I installed them.. 

I think the EV14 is a nice upgrade.