startup problem

[tnord]

i've been having this problem for about a year now, but since i went back to college i didn't really have the desire or income to try and fix it. but now i'm back out and working so i'd like to sort this out finally.

 

when i try and start the truck it'll always turn over, but doesn't always "catch fire" and actually start. sometimes it will catch a little bit, sputter around 100-200 rpm for a second then get going and idle normally. other times it doesn't start, but i'll let it sit for 3 seconds or so, turn the key again, and it fires up.

 

it seemed to be getting worse when i was getting 90 octane fuel from the same kwik-stop for about 6months. now i've been getting 87 octane from the same phillips 66 for quite a while and it seems to be getting better.

 

lately, it also seems as though when the truck is cold (in the morning going to work, or in the afternoon going home) it is more likely to start on the first try. but if i've been driving for a while, get out for 5 minutes, then try and start it again it doesn't start until the second try. this isn't 100% accurate, but it seems to be trending this way.

 

since the middle of last summer i've also noticed a decrease in power and fuel economy. i say this because i tow a 5000lb load over the same roads at the exact same speed a couple times a year, and the transmission has been downshifting to gain more power even on flat land, and i always keep track of my mpg. lately i've been down to 13, and towing is about 10mpg. i used to get more like 15 and 13.

 

i also have an exhaust leak that i had looked at around christmas. i was told that it's coming from around the drivers side header, which means before the o2 sensor. the exhaust leak has also been getting worse over the last year.

 

2001 100k mile 5.3l 4x4 Z71 for reference.

 

this is as much background as i can come up with. feel free to take a guess as to the problem.

 

thanks.

[sonjaab]

I will place a bet on a faulty Fuel pressure regulator............

 

Easy to check !!!!!!!!!!

[tnord]

how would i go about doing that?

[sonjaab]

Do a quick search on the fuel press. reg.

The topic with pics and simple

instructions will come up............geo

[tnord]

i'll try it, thanks.

 

any other guesses?

[sonjaab]

For a pic check out http://www.gm-trucks.com/forums/index.php?...topic=45038&hl=

 

Now heres how to check: Locate FPR

Start and run engine..........Turn engine OFF..........

Pull off rubber/plastic hose off nipple of FPR................

If WET with fuel..Its BAD !!!!!!!!!!!!!!!!

 

NOTE: Use CAUTION when pulling line off FPR body.

Have a rag underneath for dripping fuel (if any) !!!!

No need for a engine fire!

 

Easy and takes 5 minutes to check

[tnord]

tried a new fpr....didn't work.

 

doesn't like to start cold.....does better warm.

[sflichel]

I would suspect something in the ignition circuit is acting up when hot. Thats where I would be looking.

[gmcsierra01]

Sorry to thread jack but..I'm having the same problem with my 01 gmc sierra 1500 5.3L v8. In the morning it hesitates to start have to try a couple of times then it will start and when its warm starts with no problem and plus I hear this air leak from sumwhere near the gas tank but smell no gas

[redvett]

While your fixing things the exhaust leak has to be fixed. O2 is reading lean and adding fuel..

[tnord]

i agree that the exhaust leak needs to be fixed.....but it can't be the reason it doesn't start on the first try.

[gmcsierra01]

any other ideas what it can be? this problem is driving me

[Bish]

any other ideas what it can be? this problem is driving me

 

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Change your fuel filter lately?

[gmcsierra01]

any other ideas what it can be? this problem is driving me

 

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Change your fuel filter lately?

 

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yea after I bought the truck

[ChevyTech007]

You need to check your fuel pressure when its cold. I bet your looking at a fuel pump. $$$$