Hard Start

I have a 1999 Silverado with the 5.3L engine.

After driving it and shutting it off, if I go back out a short time later it starts hard. I have to give it gas and it stumbles the first few seconds but then runs fine. I will also occasionally smell raw fuel after it does this.

If it has sat and totally cooled down it starts right up.

Any thoughts on what is going on?


Thanks,

Gary

Fuel Pressure check at the time in question would be valuable. Injectors may be starving for fuel from low fuel pressure.

I have a 1999 Silverado with the 5.3L engine.

After driving it and shutting it off, if I go back out a short time later it starts hard. I have to give it gas and it stumbles the first few seconds but then runs fine. I will also occasionally smell raw fuel after it does this.

If it has sat and totally cooled down it starts right up.

Any thoughts on what is going on?

Gary


Thanks,

since it does start good cold that means it should have the proper fuel pressure. whenever it is a hard start after engine is running then the injector leaking may be the problem. with a 99 the fuel regulator vacuum portion may be leaking fuel into the intake also flooding the engine.

use fuel gauge key on eng off see if the fuel pressure holds .. if it drops rapidly pull off the reg vac line see if it has fuel smells or fuel..if that's good then it maybe the injectors..pressures 53-62psi. engine running should be about 57 psi if perfect lower if the pump is loosing it... 50psi is the threshold on engine start. replace fuel filter @40K miles. cut open and see if its good or bad then adjust to your fuel supplier quality of product.

lastly if this is good then it maybe the ECT which at this age including the electrical connector needs replacing.. driver side of block next to #1 cyl.

these issues most times will not throw codes. this continuing will cause the converters to over heat and plug up.

whenever it is a hard start after engine is running then the injector leaking may be the problem.



Thanks for the suggestions!

I was wondering if maybe the injectors were leaking. I've heard of that previously. Is that something fuel injector cleaner might help?

Thanks for the suggestions!

I was wondering if maybe the injectors were leaking. I've heard of that previously. Is that something fuel injector cleaner might help?

you do have a fuel filter this should be replaced. then I would add techron injector cleaner with higher octane fuel . use a top tier fuel supplier like SHELL/MOBIL /BP .. THESE fuel companies are recommended because of the fuel additives included which helps reduce injector contamination. Also adding 3 OZ of marvel mystery oil to the fuel tank on refueling also reduces corrosion and fuel issues , as well as improving power and MPG.. alcohol fuels are not good esp, if you keep your tank low on fuel .. air is water and its a bad mix in the tank. things grow in there.. with a fuel gauge do the test..