1999 Silverado hard to start when warm

[blangan]

I have a 99 Silverado Z71, 5.3 Vortec with 105,000 miles on it. Over the past two months, it has become increasingly hard to start once the engine is warmed up. It starts fine when cold. I now have to give it gas to get it started and can then smell raw gas as if it were flooded. It has also stalled on me twice in the last month, something it has never done before. My initial thoughts were with the fuel pump or pressure regulator but it starts right up when cold and runs fine once started. I am wondering if the EVAP system could be failing and could this cause this type of problem or if someone else has had a similar experience.

I have changed the air and fuel filters, spark plugs and have run injector cleaner through a couple of times.

Thanks for your help!

[louisanagambler]

YOUR SPARK PLUGS HAVE BLOWN

[dracer398]

Blangan,

I'd start first with a good tune up and by checking the fuel pressure after the engine is warmed up to operating temperature. (I'm assuming that you have access to a fuel pressure gauge) I'm not sure of the minimum pressure value but I think it's got to be somewhere around 60 to 66psi. Also I would suggest buying a good repair manual for the proper procedure. (I have a Haynes manual that outlines the procedure very well. The cost of the manual is around $15.00) If the pressure is low it won't start. Sometimes if it pump is bad cycling the ignition switch on and off several times will build up the pressure enough to allow the engine to start. Also in your tune up, include a new fuel filter.



Good Luck!

[dracer398]

Blagan,

I briefly glanced at your post and reacted before completely finishing. I see that you covered the tune up so I'd go with the pressure test.

Good Luck!

[jdod85]

I had the same problem with my 99 GMC. It was the fuel pressure regulator. $72 at the dealer. Its on the drivers side fuel rail. It has a vaccume line to it. It is very easy to take out and replace. After I replaced it my truck ran like new again.

[Greg1and]

I have the same problem with my 99 Silverado Z71. I had taken it to several mechanics trying to track down the problem. In the mean time I had it tuned up, changed the spark plugs and wires, changed the fuel filters (including the one in the gas tank), played with the idle, and nothing worked. Now I just spoke to my fourth mechanic and this may sound a little like Blinker Fluid but, he said it was the injector pulse. He said the when you stop your truck the injector is not closing fully that is why it smells like you are flooding out and that is also why after you have let it set overnight and it dried out you don’t have the problem. On my tuck I have a programmable Superchip and he advised me to play with that to see if I could tune it down a bit. I have not tried this yet but if you would like to find out what happened I would be glad to share it with you!

[Glamis9]

Greg1and,
What happened when you played with the injector pulse? I have the same exact problem in my truck, but i don't have the programable superchip, is there a way to change my settings w/o that chip?

[headhunter37]

I have the EXACT same problem with my 99 silverado 5.3l

Did you guys try the pressure regulator or the pulse injector?

My buddy told me it's imperative to run AC Delco Prof Platinum plugs, I put them in last night and it seemed better but started doing the same thing today.

Not sure what else to do, please advise if you have fixed yours and know what to do???

[Poncharelo]

Sounds like what i had ast month, i changed the fuel pressure regulater because when i pulled the vacume line fuel started coming out. I was getting that unburned fuel smell and it was hard to start after i sat for a while.

[99-chevyguy]

Originally Posted by blangan

I have a 99 Silverado Z71, 5.3 Vortec with 105,000 miles on it. Over the past two months, it has become increasingly hard to start once the engine is warmed up. It starts fine when cold. I now have to give it gas to get it started and can then smell raw gas as if it were flooded. It has also stalled on me twice in the last month, something it has never done before. My initial thoughts were with the fuel pump or pressure regulator but it starts right up when cold and runs fine once started. I am wondering if the EVAP system could be failing and could this cause this type of problem or if someone else has had a similar experience.

I have changed the air and fuel filters, spark plugs and have run injector cleaner through a couple of times.

Thanks for your help!

I had the same problem with my 99 chevy it was the fuel pressure regulator
it located on the fuel rail on the right side facing the engine it has a single vac hose on it.

when I pulled it running it was pushing out raw gas the vac hose was sucking it in the motor causing plugs to fal, rough idle, and learching.

I replace it and it cleared it right up the part cost me around 75.00 dollars

I hope this works for you

[alwcurlz]

Same issue here as well. Starts great when cold, but nearly impossible once warm to start. Also, the valves are clattering with quick throttle input. I'm certain those two are connected! I'm going to get that fuel pressure regulator replaced! Already posted this question on GM-Trucks.com.


1999 Silverado Z71 5.3 135,000 miles
New spark plugs
Air filter good
New fuel filter
$160 BG 3 part with BG tool, fuel/air system purging cleaning process done

[klausbarbie]

see Ebay for a fuel pressure regulator, look for part number PR217T. I paid $40.00 plus shipping for mine. delivery was 2nd day. It fixed the problem.