[adriano.ro]

Hi, is about CFmoto Z8 2014,after I rebuilt all the engine,put all together start ok,run ok on idle but the cylinder #1 won't run,I got spark but fuel is shut off about 4 second after I start de engine,I swap O2 sensors,injectors,coils,the same results.

If I unplug the T-map sensor( air temperature and pressure sensor) will run ,not so steady idle but will run strong,EFI light is on.

I have changed ECU too,but no changes.

No errore codes on dashboard.
The service manual is so vogue.

[doug80638]

Sounds like you did what I might do; swapping components between the two cylinders.

How did you determine that  fuel wasn't getting to that cylinder?

Assuming it's a fuel issue ....

Check fuel pressure - should be above 40psi (closer to 50).

Check the trigger signal to the injector.

If the trigger signal is faulty, then trace the wiring for that injector back to locate the break.

It's the signal is OK, look for a kinked or clogged fuel line to the injector.

[NMKawierider]

Hi, is about CFmoto Z8 2014,after I rebuilt all the engine,put all together start ok,run ok on idle but the cylinder #1 won't run,I got spark but fuel is shut off about 4 second after I start de engine,I swap O2 sensors,injectors,coils,the same results.

If I unplug the T-map sensor( air temperature and pressure sensor) will run ,not so steady idle but will run strong,EFI light is on.

I have changed ECU too,but no changes.

No errore codes on dashboard.
The service manual is so vogue.

You say the EFI light is on. The manual shows you how to make it flash the error code...and how to read it. There is also a list of fault codes in the manual to compare it to. With all the switching you have done it has to be ...obviously..something that hasn't been and something that shows up as an error like the CPS pickup or one of it's leads..something like that.

[adriano.ro]

Sounds like you did what I might do; swapping components between the two cylinders.

How did you determine that  fuel wasn't getting to that cylinder?

Assuming it's a fuel issue ....

Check fuel pressure - should be above 40psi (closer to 50).

Check the trigger signal to the injector.

If the trigger signal is faulty, then trace the wiring for that injector back to locate the break.


It's the signal is OK, look for a kinked or clogged fuel line to the injector.

The problem is on cylinder 1 ,no meters what I do. Injectors are cleaned.

After the idle a while, the spark plug on cylinder #1 is dry,and I put an plug on ignition coil spark is there,when engine run.


The wiring seems ok,because signal is coming if I unplug T-map sensor.

[adriano.ro]

Hi, is about CFmoto Z8 2014,after I rebuilt all the engine,put all together start ok,run ok on idle but the cylinder #1 won't run,I got spark but fuel is shut off about 4 second after I start de engine,I swap O2 sensors,injectors,coils,the same results.

If I unplug the T-map sensor( air temperature and pressure sensor) will run ,not so steady idle but will run strong,EFI light is on.

I have changed ECU too,but no changes.

No errore codes on dashboard.
The service manual is so vogue.

You say the EFI light is on. The manual shows you how to make it flash the error code...and how to read it. There is also a list of fault codes in the manual to compare it to. With all the switching you have done it has to be ...obviously..something that hasn't been and something that shows up as an error like the CPS pickup or one of it's leads..something like that.

EFI light is on only if I unplug T-map sensor,otherwise no warning lights,or error codes on display.

[NMKawierider]

Hi, is about CFmoto Z8 2014,after I rebuilt all the engine,put all together start ok,run ok on idle but the cylinder #1 won't run,I got spark but fuel is shut off about 4 second after I start de engine,I swap O2 sensors,injectors,coils,the same results.

If I unplug the T-map sensor( air temperature and pressure sensor) will run ,not so steady idle but will run strong,EFI light is on.

I have changed ECU too,but no changes.

No errore codes on dashboard.
The service manual is so vogue.

You say the EFI light is on. The manual shows you how to make it flash the error code...and how to read it. There is also a list of fault codes in the manual to compare it to. With all the switching you have done it has to be ...obviously..something that hasn't been and something that shows up as an error like the CPS pickup or one of it's leads..something like that.

EFI light is on only if I unplug T-map sensor,otherwise no warning lights,or error codes on display.

Then it's not sensor or component-related...ie nothing that the ECM detects an error about so it must be something within a connection, the harness or fuel supply..something like that.

[doug80638]

If no ECU light, then the circuit to the injectors should be fine.

That leaves an obstruction in the fuel system or clogged injector. (assumes proper fuel pressure)

[NMKawierider]

If no ECU light, then the circuit to the injectors should be fine.

That leaves an obstruction in the fuel system or clogged injector. (assumes proper fuel pressure)

Yeah he's switched injectors and neither on #1 will trigger...yet there is no error code...and he's changes the ECM so that just leaves no fuel to that injector. Better take a pressure reading.

[Z8rider]

what makes you so sure it is a fuel issue? Have you put a noid light on the injector?

The reason I have doubts about it being fuel related is that A LOT of people end up setting the cam timing 180 degrees off and you won't get combustion on cylinder #1.... you did say you just rebuilt the engine...

[doug80638]

That is a very interesting observation, and I'd love to learn more about it.

I think I get it. You're saying that the cam for #1 could be out 180 degrees, but the cam on cylinder 2 is not, yes? Or is it something different?

He said the plug was dry. I would have expected it to be wet if the injector was pulsing in fuel and the cylinder was not firing.

The ECU should fire off a code if the injector circuit is not within spec.

[adriano.ro]

what makes you so sure it is a fuel issue? Have you put a noid light on the injector?

The reason I have doubts about it being fuel related is that A LOT of people end up setting the cam timing 180 degrees off and you won't get combustion on cylinder #1.... you did say you just rebuilt the engine...

If the timing isn't spot on ,why when I unplug the T-map sensor the engine run ok?

How I know is fuel problem ? Simple, 1: the plug is stone dry , 2: with engine idling,  I get below 0.2 volt on the wire that needs to have about 5 volts.

[adriano.ro]

If no ECU light, then the circuit to the injectors should be fine.

That leaves an obstruction in the fuel system or clogged injector. (assumes proper fuel pressure)

Clogged injectors is out of list,because if i swap the injectors the problem still on the cylinder #1 all the time.

[ctdls]

I'm not a fan of swapping a multitude of parts, the danger is you end with another problem & now are chasing more than one issue. The original plus the new self inflicted. If you have determined it is an injector using the noid is indicating is a pulse is present by all means swap the injector for verification. To wholesale swap all the components mentioned is desperation.

Myself I'm curious why the original rebuild & if there is a connection between the two. If this problem was not there then for sure you have to question the rebuild & cam timing needs to be ruled out. If you do a compression test(I have not seen any comment about that) & a leak down that should rule out any mechanical condition. Both test need to completed for timing verification. I would do this regardless just to rule it out.

Un plugging the MAP sensor is not verification you don't have a mechanical issue in my mind. When the ECU see's a fault what is it doing, protecting the engine from damage & may add extra fuel as well retard ignition timing. Maybe that is enough to make the bad cylinder fire.......

[Z8rider]

just check the cam timing. this is a good way to verify it (not how to set it, JUST to verify). When one side is at TDC compression, the opposite side should be in this position.

[adriano.ro]

just check the cam timing. this is a good way to verify it (not how to set it, JUST to verify). When one side is at TDC compression, the opposite side should be in this position.

Timing is spot on,I recheck about an hour ago.