Hard starts when hot

When the engine is hot and my truck sits for 10-15 minutes, the engine will crank and crank but not start on the first attempt to restart it. This is accompanied by the smell of gas.

It always starts up after a long crank or on the second or third attempt, but the issue is still concerning to me because I worry that it will get worse or put stress on other engine components.

I already replaced the fuel pump (Denso), as well as the strainer, gasket, and fuel filter (Toyota). Things improved a little bit, but the same issue will still come up sometimes when the engine is very hot.

I took it to a mechanic to diagnose the problem. They told me that the issue had to be with the new fuel pump I installed and encouraged me to buy a new one under Denso's warranty. They read low fuel pressure (10psi when spec is 38-43 or something like that) at the fuel filter, which is what they based their recommendation on.

What I don't understand is how the new pump would be defective in exactly the same way as the old one. I would assume that if it was defective, it would have other issues but I haven't really experienced any other symptoms of a bad fuel pump. There does seem to be a louder whine coming from it than from the old one, I assumed that was just the newer unit working correctly.

So, should I warranty out the one I installed and try again? Or is there something else that could be causing low fuel pressure and hard starts when hot that I'm missing? Injectors? MAF? Fuel lines clogged somewhere? Gas tank issue or something wrong with a different component of the fuel pump assembly?

 

Any check engine light?
EVAP codes can cause flooding at hot starts. P0446 P0442
Faulty fuel tank vapor pressure sensor or open Purge Selnoid

 

No lights. Only recent one was a lean code that went away after cleaning the MAF.

 

Hard starts when hot is a common symptom of leaky fuel injectors. When the engine is shut off the injectors continue to leak fuel making it hard to start until the leaked fuel has evaporated. Meaning cold starts are usually normal, and the hot ones harder.

Might also explain the smell of gas

 

Had this issue in my old GMC, which was one of the reasons I ultimately traded it in. Mine would often start and then the RPMs would jump several times before stalling and then it would have a hard start. Replaced the manifold, which was cracked, and that also replaced one of the cats. The issue got better, but never fully went away. I wasn't able to look into the fuel injectors though because of their location.

 

That makes a lot of sense.

I'll look into injector replacements or rebuilding before I redo the fuel pump, I think I saw that Motorwest was supposed to be good

 

I recently had this issue with hard starting and actually my problem was the battery. I guess the other battery wasn’t giving enough to the coil to fire right away. I had good fuel pressure and smelled gas on start up. So it was getting gas but wasn’t getting spark. Mine started fine in the morning as well

 

Having a similar problem....did you ever get resolution? and if so what was cause?

 

Injectors for me rectified my Hot no Start
But
There is a plethora of easier fixes if you search
I went through them
Took chance on injectors

 

Thanks for the update....My Taco is at 338K miles and we are working our way through issues....when it runs it runs great, but this starting thing is a nagging problem....I'm close to just deciding it is injectors....did you do the job yourself or pay a shop? and if you did it yourself how was it?

 

Not too bad
Lemme find my thread

Now I come from the school….
“If your in there….might as well do everything “
I did
But not my DD…..prepping mechanically for 16yr old

thread will definitely help you with my trials and tribulations

 

https://www.tacomaworld.com/threads/2-4l-2rz-injector-installation-a-tip-and-question.818472/

 

Sure fire way to test injectors is to remove the rail with them seated in the rail then turning in the key, you’ll be able to see if there’s any leak.

a borescope in the cylinders works as well but you need one capable of side view.

this sounds like evap purge issue or excessive carob to me personally

 

https://www.tacomaworld.com/threads/throttle-body-iac-cleaning.819537/

 

Mine was a fuel pump when I had the same issues

 

In order for the fuel pump to develop any pressure there has to be a restriction in the “system”. In a properly working system the fuel pressure relief valve and the injectors provide that restriction. If the injectors leak and the pressure relief is bad then inadequate pressure wont develop. The other rare issue is the fuel line from the pump to the metal outlet tubing inside the tank. It should be a fuel line rated to be submersed. I have seen this mostly on vehicle that sit for extended periods, the line just goes soft and then a tear develops and you dont notice it until you pull the fuel module out.