[colorider2]

I have a 2018 Zforce 800 trail and I recently replaced spark plugs and replaced the fuel filter due to an occasional stall that would happen. After the changes, she ran beautifully, no issues. After sitting for a week in the garage, the engine will no longer turnover. I can rev the engine with my foot on the throttle, but as soon as I let go, the engine dies. Battery is fine - I even tried a brand new battery that was fully charged.
 
What else should I check? Starter? ECU? 

Thanks

[NMKawierider]

I have a 2018 Zforce 800 trail and I recently replaced spark plugs and replaced the fuel filter due to an occasional stall that would happen. After the changes, she ran beautifully, no issues. After sitting for a week in the garage, the engine will no longer turnover. I can rev the engine with my foot on the throttle, but as soon as I let go, the engine dies. Battery is fine - I even tried a brand new battery that was fully charged.
 
What else should I check? Starter? ECU? 

Thanks

I'm confused. In one sentence you say it won't "turn over" meaning to most people the starter isn't rotating the engine and it won't start. In the next sentence you say you can "rev the engine" with your foot and let off it dies..meaning it was running. So I'm assuming it will start but it just runs like it has low power to the ignition circuit, or low fuel pressure (both can be checked) or...she's jumped time..which also can be checked. You say you changed the fuel filter. By chance it wasn't put in with the arrows in the wrong direction or..is there any chance anything could have gotten in the line after the filter that could have made it's way to the injectors? Some things to look at.

[colorider2]

Yeah I wrote the post in haste, my apologies. If I turn the key, the the engine will fire and then immediately die, unless I keep my foot on the throttle. Fuel filter is installed the right way, double checked. I'll check for the things you mentioned. Thanks.

[colorider2]

So turns out the throttle cable was not tensioned properly. There was enough slack in the cable that it prevented the engine from idling. I never would have thought to check this if I did not have a buddy looking at the TB while I tried starting.   

My new concern is that there is now no more adjustment left for the cable. It feels like it could be tensioned just a bit more.   Is there any adjustment available at the pedal? Or should I look into possibly getting a new cable.

Thanks

[NMKawierider]

Idle is never set by tension on the cable..especially on an EFI machine. It is set by the ECU by controlling the Idle Air Control Valve in combination with the pulse width of the injectors to maintain a set RPM monitored by the engine speed sensor. These valves can become stuck or stop working...but can be cleaned and free-up if just stuck. All you have done is force the butterfly open allowing some air in..but that will also be a problem as the engines are rubber mounted and move and as such, the distance between the ends of the cable will also change jerking the butterfly open and closed as that distance changes. The cable must have enough play to compensate for that.. and frame flex. There are some YT videos on cleaning IACVs. May have to remove the TB as it is on or built in it.

[colorider2]

I understand what you're saying. It's strange as I had previously cleaned the IACV and the TB with MAF cleaner and electrically tested the valve and everything seemed to check out. On my older race cars, I would be able to shake the IACV and hear it opening/closing or whether it was stuck, but I don't hear that with this particular IACV. Don't know if I should be able to or not. I'll pull it again and check. These valves are cheap enough, I may order one, swap it out and see if it makes a difference.

[NMKawierider]

They stick more often then they go bad. Sense they still get their air through the filtered intake track, if it has had the stock paper filter it can get enough dust particles to jam it...and if it has the Unifilter some have found dried filter oil treatment in them that has bound them.A good reason to use a paper towel inside the filter after applying the treatment to get the excess. Just spray carb cleaner is best for the valve The mass airflow sensor spray cleaner may not be enough. Might also check all the electrical connections.

[colorider2]

Thank you I will try the carb cleaner. I did recently replace the paper filter that the PO had a foam sleave on that was caked in oil with a uni.

[colorider2]

Just to close this thread out (hopefully), it turns out the IACV was stuck in the extended (closed?) position. I replaced the valve, readjusted the cable back to where it was originally, and everything seems to be fine for the moment.

[NMKawierider]

Good.