2010 Prius will not stay running after Head Gasket replacement.

Hi Paul,

Checking fuel pressure seems like the next logical step: How to check fuel pressure | PriusChat

The engine isn't actually as you say "starts and runs" it's just being spun by the hybrid battery and not starting... This is a common misconception when people work on Prius because most cars have starters that don't spin the engine very fast and Prius has the whole hybrid system to spin the engine so it sounds like the engine is running when its only being spun by the electric motor in the transmisison.

Also Autel 808 might not be programmed with Prius specific hybrid codes so you might want to try an OBD2 reader with Car Scanner App or Dr. Prius app to see if you can get some error codes? Or alternatively you can get a Mini-VCI adapter online for less than $40 and most of them come with a hacked version of Toyota Techstream software that runs on old Windows computers.

Lastly, just as you suspect, you can only spin the engine with the hybrid battery a limited amount of times without starting before the battery drains to a voltage low enough to no longer work. The fix for that is a high voltage trickle charger to charge and balance the battery pack. Maxx Volts and Hybrid Automotive make consumer versions that are expensive, or you can build one for a $100: Build Hybrid Battery Maintenance Gear For Under $100 | PriusChat

 

Double check and see if all the vacuum hoses are connected.

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PCV hose to intake? That one did me in lately.

 

You want to get a scanner that can read ABS codes and basic p codes on the Prius I have an Innova brand that does very well I think it's a 3102 3152 it has a red ABS button on it this thing saved my life during the engine change on my 13 persona which after the engine replacement had all kinds of codes and one that was killing us that we didn't even realize was something to do with the air conditioning circuit after we replace the engine the air conditioning was never disconnected as far as gas and hoses go but was unplugged to lay the compressor in the engine bay while we dropped in the new engine so we could screw the compressor back up and not have to gas it up. During restart after engine transmission change and what have you The car would not start it would spin it would move it would drive a bit and the battery would go from full bars down to zero it literally in minutes. The thing that worked for me was at least to get the car driving was silly stupid The minute I unplugged the air conditioning compressor The battery stopped draining the HV battery and the engine would run and fire on all four cylinders and charge the battery and it wouldn't die If I got out and plugged the air conditioning compressor up I could see the battery starting to die immediately on the display in the car. So I left the battery unplugged for a few days while we tweaked the vehicle and drove the car very locally and during that time I discovered the HV battery was falling on its face because I undid the panel in the back lifted the cover and saw all the frosted bus bar nuts. So I parked the persona got in the '09 tourer. And drove up to the hybrid doctor and I think it's Fairfax Virginia came back with a new battery rack balanced ready to go dropped it in the persona and never had a problem since.

 

Check that the shut off switch on the hybrid battery is actually closed.
Someone had a similar problem, and they remove it and reinstalled it and
everything worked.

I would "guess" since it was working before the head gasket, that something is not
connected, or completely connected.

It's a pain, but going over every connector, slowly, and disconnectin and reconnecting them
and checking no pins are bent, and making SURE it is connected properly, you'll find one
that is not so tight.

 

Did you try starting up in maintenance mode? Just curious. I'm not suggesting a solution.

 

Best to not try any more? Due to:

 

There has to be something disconnected or possibly damaged wiring.

 

Any update?