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Discussion Starter · #1 ·
So I didnt use the bike for a month and when I go to use it again it cranks, i hear the pistons pushing out air with no problem, but it doesnt start. I took it to a mechanic who told me I have bad compression in both cylinders from the valves so that is where I started and did the following work.

-Installed a used valve cover and head from a bike with 3k miles. Checked first to make sure the valves didnt leak by using the water method.

-Installed new piston rings for good measure.

-Installed all new gaskets accordingly.

-Properly set up the timing chain.

After all this it was the same issue, I was pissed and heartbroken so I dug in deeper.

-Replaced the fuel pump along with its wires and fuel pressure regulator.

-Verified there was spark emitting from the spark plugs and coils.

-Connected fuel injectors to power to make sure they "click". Resistances are in spec.

-Checked for continuity in all fuses, all involved wires, the relays in the relay box, crankshaft position sensor.

-Installed a used ECU known to work.

-I went back to the injectors and removed the whole fuel rail with the injectors still installed and connected to their plugs, and the rail connected to the gas tank. I wanted to see if they would spray when i turned on and cranked the bike and they did not. This seems to be the true issue, that there is no fuel delivery for some reason.

I'm lost ya'll. Is it possible for the fuel injectors to click but not actually spray fuel? Or can it be some other sensor that causes this? :(
 

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Old fuel can gum up anything if it sits for a while. In general, as fuel ages it breaks down which is why fuel stabilizer is recommended for long-term storage. One month shouldn't be enough to cause problems, but if the fuel in the tank was already getting old and wasn't stabilized, sitting for a month could be enough to cause some issues.
Sounds like all your electrical is working and that the solenoids in the injectors are opening as they should. If the solenoids were jammed with gunk, you likely wouldn't get the clicking.
Assuming the electrical is fine, you probably have a physical blockage of dried gas somewhere in the system. I would think the most likely culprit would be clogged injector nozzles, since they have tiny holes to atomize the fuel. I've heard (but not tried) various methods for dissolving the residue on injector nozzles that might work for you. To answer your question, yes it is possible for the injectors to click but the nozzle still be blocked with dried fuel residue.
Do you have (or can you check) pressure at the rail? If you have rail pressure within spec, it's most likely clogged injectors, if not you have to look upstream for a blockage, but where you replaced the pump unit (including filter and regulator) I feel that would be less likely.
 

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That's a ton of work, and unfortunately plenty of things to go wrong along the way.

I think I'd try a shot of Starter Fluid to see if the engine will "pop" - confirming at least you have spark.

Open each TB and give it a quick shot - not too much. Make sure the battery is fully charged.

As IW noted - check that you have fuel pressure. Possibly a fuel pump issue. Note that many aftermarket pumps will flow fuel but not supply adequate pressure.
 

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Discussion Starter · #4 ·
Old fuel can gum up anything if it sits for a while. In general, as fuel ages it breaks down which is why fuel stabilizer is recommended for long-term storage. One month shouldn't be enough to cause problems, but if the fuel in the tank was already getting old and wasn't stabilized, sitting for a month could be enough to cause some issues.
Sounds like all your electrical is working and that the solenoids in the injectors are opening as they should. If the solenoids were jammed with gunk, you likely wouldn't get the clicking.
Assuming the electrical is fine, you probably have a physical blockage of dried gas somewhere in the system. I would think the most likely culprit would be clogged injector nozzles, since they have tiny holes to atomize the fuel. I've heard (but not tried) various methods for dissolving the residue on injector nozzles that might work for you. To answer your question, yes it is possible for the injectors to click but the nozzle still be blocked with dried fuel residue.
Do you have (or can you check) pressure at the rail? If you have rail pressure within spec, it's most likely clogged injectors, if not you have to look upstream for a blockage, but where you replaced the pump unit (including filter and regulator) I feel that would be less likely.
So i had an extra boba tea straw laying around and i thought heyyyyyyyy. Boba straws are huge enough to fit on the end of my injector. So i put the straw on it and filled it with a bit of water since i didnt want to inhale gas fumes, and i supported the combo on a mug where the water could spray into. I used some alligator clips connected to the battery and injector, and as i blew into the straw while powering the injector on and off the water sprayed out just fine. Both injectors did. Unfortunately i do not have the means to test the fuel pressure.
 

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Discussion Starter · #5 ·
That's a ton of work, and unfortunately plenty of things to go wrong along the way.

I think I'd try a shot of Starter Fluid to see if the engine will "pop" - confirming at least you have spark.

Open each TB and give it a quick shot - not too much. Make sure the battery is fully charged.

As IW noted - check that you have fuel pressure. Possibly a fuel pump issue. Note that many aftermarket pumps will flow fuel but not supply adequate pressure.
The starter fluid does make it run for a second or two. Im assuming an aftermarket pump would pressurize enough to at least idle the bike, but i cant test the pressure unfortunately.
 

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If you have an aftermarket fuel pump, it is most likely the problem from what I have seen.
Could be a bad pump for sure. I'm not familiar with good/bad experiences with aftermarket pumps, but it wouldn't surprise me if a "good" aftermarket pump underperforms.

Do you hear the pump prime when you first turn the key/stop switch on? Should "whirrrrr" for a few seconds. If not, you've got a dead pump or no power at the connector. Where you checked for continuity and tried a known-good ECU, I expect you've got juice at the connector, so no prime would point to a dead pump, but I'd measure voltage at the pump connector when the pump is supposed to prime if you don't get the "whirr" just to be sure. This will only identify if the pump (or associated circuit) is dead, not if the pump "works" but doesn't meet pressure requirements as noted above.


The other thing that comes to mind is the tank vent. If it's blocked somehow (and I seem to recall a few people having the issue) the tank won't let in air to replace the used fuel volume. After a few seconds, the vacuum inside the tank is too much for the pump to handle. Do you notice a sucking-air sound when opening the gas tank?

You could try starting with the cap open, but there are risks associated with running a bike with the cap open. If you choose to try this, take all necessary precautions etc. etc. etc. If the bike runs with the cap open, but not with the cap closed, the tank vent is the most likely culprit.
The other option would be to start/run/try-and-start the bike for a little bit with the tank closed, then without waiting too long and with the bike shut off, open the cap and listen for a rush of air entering the tank.

Is it a California model bike? Cal bikes have an EVAP can on the vent line, so troubleshooting a blocked vent might be different.
If it is a non-Cal bike, the vent line and drain line meet at the Breather (a little white plastic chummy) on the left side of the tank near the forward lower edge. The breather has a short length of line from the tank drain, and a long drain line coming out the bottom, and connects directly to the side of the tank where the vent line comes out. Inside the tank, this vent line is connected to the fuller neck area under the gas cap, look for a little post with a hole down the middle at about the 10:00 position. The gas cap has a little rubber seal that lines up with this post. Inside the cap itself is a labyrinth seal, and a little hole right in the middle of the cap (bottom) lets the air in or out of the tank.


DO NOT try and use compressed air to clear out the cap itself. The labyrinth seal could be damaged. DO look at the little orange rubber seal where the cap meets the vent post and make sure it looks in good shape.
DO check vent and drain hoses to make sure there are no kinks.
DO apply compressed air to the little post inside the filler neck area to try and clear any blockages in the vent line. May as well try and clear the drain hole while you're in there, it's the other hole under the cap at probably the 4:00 position around the filler neck (no little post for this one).

If the vent lines are clear and you still pull tank vacuum, it's likely your cap has a failed labyrinth seal. I am not certain if the cap can be disassembled and repaired.
 
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