Cold starts perfectly but once warmed up difficult to restart

High mileage 2.7 2TR-FE 5 speed. Replaced head gasket which solved coolant pressurization problem. Reassembled engine with a few hickups along the way, (one of the intake vac hoses popped off during reassembly-forum advice fixed that quickly.) Now engine cold starts and runs really well but is difficult to restart once warmed up. Must be cranked 3 or 4 times. Almost like there is no fuel pressure. No codes showing but curious values shown. I'll post pics

 

How long does it have to sit before it easily starts? Has the fuel economy dropped at all? Does the exhaust smell ''gassy?"

Is it going back to open loop from closed loop? A failing temp sensor or similar can cause issues like this. In open loop it uses a set parameter, once it switches over to closed it uses feedback for fuel amounts.

Or, you have a failing injector or two leaking when turned off and pooling in the cylinder. From cold it has evaporated or drained past the rings.

 

If more than a couple of minutes, its a difficult restart. Fuel economy tbd. Exhaust smell normal. New injectors and coils.

I'm trying to upload pics from the scanner showing a curious voltage reading from the 02 sensor but having difficulty with the upload. I will measure the time issue and check mileage tonight. I am guessing that I may have forgotten to reinstall or connect something to do with fuel pressure. The reassembly is kind of difficult for a newbie and some things are really difficult to see and/or not shown in manuals.

 

Is there air outside? Yes.
Do you have spark plugs? Yes.

Id test the fuel system.
And maybe the ability for the engine to run right such as compression.

if you have fuel delivery problems it doesn’t matter how good your compression is.

I don’t consider open vs closed loop because I replaced my O2 sensors.

I cannot tell you how many vehicles O2 sensors and fuel delivery systems I have replaced at significantly earlier mileage. Te Tacoma is not made of gold. It is a vehicle just as other vehicles are vehicles. With often the same parts by the same manufacturers that some folks pretend is not the case.

 

my son's honda crv was doing this exact thing last week... his was a coolant temperature sensor that wasn't working and telling intake system that it was always cold and it was always choking the throttle body and wouldn't hardly start when warm. Not sure if this could be happening on a tacoma, but good luck... also you could smell a lot of fuel around the engine.

 

Bad oxygen sensor won't keep a engine from starting. Curious to see what temp sensor reading is when problem happens. That's the first sensor the computer looks at on startup. Oxygen sensors don't come into play until later..

There should be a chart somewhere for testing temp sensor resistance values at various temperatures

Also maybe get your hands on a fuel pressure gauge, duct tape it to the windshield and go for a drive. Might be able to catch a weak fuel pump when hot