99 2500 7.4 L Hard Start

[rodfrancis]

I have 1999 3/4 ton Suburban 4x4 with a 7.4L with 46K miles on it. Cold start is quick and fine, but after a 1 hour wait it starts hard. Cranks for about 30 seconds prior to start. This only recently began, however it has idled rough since I purchased the vehicle a year ago. Dealer says the rough idle is normal. Any ideas?

Thanks

[grumpy5]

Rod, Ihave the same vehicle.Ihave had the same problemwith the rough idle.Ituned it up with new wires cap rotor, and plugs. I made the mistake of putting Bosch plugs in. They made it run worse!
If you tune it up use the ac delco plugs. My sub still idles a little rough but not as bad as before.As far as your hard start problem; does it occur after you have been driving for an hour or sitting for an hour? Can you hear the fuel pumprun befor eyou start it on the second attempt? You may want to change the fuel filter as a precaution.

[rodfrancis]

Thanks for the reply. It starts fine in the morning and is run about 30 minutes to work. If I attempt to start it after an hour it will start hard (20 - 30 seconds). It will also continue to start hard for the rest of the day after sitting for a 1/2 hour or more. After the hard start there is also a strong fuel smell under the hood. No fuel is showing up in the air filer. The pump is loud and runs, but no more than it has before. I am having it tuned up and all the filters changed before I do anything else. My mechanic agreed with your input on using AC Delco plugs.

Thanks

Rod

[pagescan]

I had the same problem and it turned out to be a leaking fuel pressure regulator. Works great now. Exact same symptoms.