Car cranking but wont start when the engine is warm.

[Roy124]

Like Tony I read from the beginning and my immediate thought was an airlock or rather vapour lock.  Check your filler cap is clean. 

The bottom line though is you need to use a mechanic that you trust rather than the main dealer.   As said,  they throw parts at it. 

Without going into fine detail my last garage saved me £1,000 fixing a pump with a nylon washer.  Dad used to work on Avro Yorks and specialised on pre-war models,  son was a part time lecturer at University.  Gold dust. 

[flash22]

No codes tho, something must have got stuck - very old fuel may have been a factor modern fuel only last 6 month before going stale/off

don't run the tank low, top it up before a 1/4 is left, a drop of premium fuel wouldn't hurt

[Roy124]

1 minute ago, flash22 said:

No codes tho, something must have got stuck - very old fuel may have been a factor modern fuel only last 6 month before going stale/off

don't run the tank low top it up before a 1/4 is left, a drop of premium fuel would not hurt

😁

[flash22]

Spell checker strikes again it dropped the nt as I forgot the apostrophe  n't

[niksgee]

Update 2 

Well today I knew could be trouble. Starting up from cold it did start, but more cranking before it did... maybe six times instead of 3. 

Today I drove to the coast. About 30 miles. It didnt feel as good today, i reached my destination, and parked in car park. Voila it wouldnt start again... the usual cranking sound... 

So remembering what you said, I opened the fuel valve. As I unscrewed the cap pppphsssh lots of pressure. The car started. I stupidly switched off the car, closed the fuel cap and tried to start. It didnt. I opened the fuel cap and it started then closed and drove off. (I should say opening the fuel cap doesnt always help it to work). Second time when I opened the fuel cap there wasn't pshsshhhh pressure as i did. 

I drove home and it was ok. I did notice though going along ring road that the car was running at 30000 rpm on the flat at 57 mph in 5th gear. It felt like it was struggling a bit more today. Nothing major, at times seemed to lack power. Or the rev counter was higher than I would have liked. 

I knew it might be too good to be true. 

[Roy124]

Do have a look at your filler cap.   As fuel is drawn into the engine the pressure in your tank will  drop.   When you undo the cap the pressure is restored. 

I have just looked at my cap.   It is not simply a seal.   Inside is a spring.   Now I guess that as the pressure in the tank drops the cap sealing is drawn in and pressure equalised.  The spring then restores the seal stopping fumes escaping. 

As said,  there needs to be some vacuum but not too much.  Your vacuum buildup suggests the cap valve is not working. 

[fordulike]

Really interesting info on the filler cap. I would never have guessed it was so important:

https://itstillruns.com/vented-gas-caps-work-5057554.html

[Cyker]

Still relatively new to me too, having had diesels until recently!

Diesel doesn't readily evaporate like petrol does, so it doesn't need such fancy things to control tank emissions - I didn't realize petrol tanks are now air tight until relatively recently! (My first petrol car's wasn't  )

 

[TonyHSD]

Fuel charcoal canister as flash already mentioned. Interestingly the additive has helped which points towards dirty fuel system canister, fuel filter, fuel lines and injectors. Could also be a fuel pump but when that goes wrong usually the car won’t start first time at cold. 

[flash22]

As i stated on the first page canister or the vent valve on the side of the intake/airbox, it's a very simple job to swap the valve 2 pipes and a connector, the valve controls the tank pressure

[niksgee]

On 8/25/2022 at 12:46 AM, niksgee said:

An update as I dont see many updates. 

As a recap toyota had my car almost 2.5 years did nothiing with it, other than replace ecu which didnt need replacing. I picked up after paying for another mot (second it was in there so long) and a FULL service. I wanted to make sure car was ok. First  day it was kind of ok, still cranking before connecting.

 

Day 2 it was back to same old.... the car would not start when warm. Ie when i had been for a drive. A pain when you drive to the shops or anything like that. 

Solution. I dont know if this is final solution for now.... but I put into the car wynns extreme system cleaner (petrol). I put in most of the bottle into half a tank, and put in the rest the next day and topped up. For the first time.... my car had no problems starting. Even after I had been for a drive and engine was warm it hasnt cut out... it is all still fingers crossed.but so far system fuel cleaner has helped well it hasnt had problems starting since. Will this be the solution? I dont know long term.... but I will report back later... as I know how important the acctual outcome can be. 

Update 3 .... so the car was starting better with the wynns but.... next day the cranking was for longer and by the time I had stopped 30 miles away, I tried to restart and it was just cranking.  It did start and I drove home, there was  a few performance issues. 

Today I put more wynns in, and filled to the top. So far it has started first time. 

Local mechanic said that if toyota couldnt find the fault, it wasnt coming up on ECU, so to look at mechanical issues that will not come up on ECU. He suggested starting with fuel filter.... 

 

It would be great if it kept going as  it has done today, with second batch of wynns.... who knows maybe it will. 

[Crustyoldavensis]

Just been reading through this thread.

Is the problem more or less noticeable depending on the weather/season?

2 stroke is good for cleaning the fuel system. I stick some in my tank occasionally in all of my vehicles, including the 2 stroke.

the fuel cap and breather could be the cause as many have said. 
Also it could be a run back thing, or an evaporative thing at the engine end.

feel all fuel lines along their full length for dampness.

 

[flash22]

The tank vent is important, a clogged canister will not throw a code, a dodgy vent valve will not throw a code in some circumstances

the tank pressure/vacuum can vary greatly if hot or cold - think of it as trying to breathe through a thin straw with your nose pinched

[Eos2]

On 8/21/2022 at 9:05 AM, Yugguy1970 said:

Howdo.

This might sound a daft question but is the air filter clogged, or the ducting to it.

We had this issue with my dads car,and it turned out to be that.

Other things are various sensors, fuel pump, but it would be useful to know any error codes seen.

Knocking from tbe back could be something as simple as rattly exhaust mounts, especially if the rubber has perished.

 

On 8/21/2022 at 9:05 AM, Yugguy1970 said:

Howdo.

This might sound a daft question but is the air filter clogged, or the ducting to it.

We had this issue with my dads car,and it turned out to be that.

Other things are various sensors, fuel pump, but it would be useful to know any error codes seen.

Knocking from tbe back could be something as simple as rattly exhaust mounts, especially if the rubber has perished.

Have you checked the water level around the engine temperature sensor. if the sensor is uncovered when the engine is cold the VCU will not enrich the injection to get the engine started. I know because it happened to a early Yaris I owned.