truck trouble shooting

[bradley300]

i've got a 99 chevy 4x4 with a 350 and its starting to have some issues. its got 140,000 miles and all of a sudden its hard to start when its cold (cranks for a while) and wont rev past 4000rpm. revs fine to 3000 then struggles to gain, and wont get past 4000.

I changed spark plugs and wires today and that cured the hard starting, but didnt help the rev problem so i'm wondering what it could be and any suggestions are appreciated

[pro-rider46]

sounds like a problem with your computer, idk tho

[TRX450RACER174]

Try a fuel filter it should be on the left frame rail my 99 had a similar problem like that you would step on it and it would hesitate then if you eased into the throttle it was fine.

[wvspeedfreak]

Sounds like either a fuel delivery problem or a possible catalytic converter restriction.Try a new fuel filter first like TRX450 said.If that doesn't help do a fuel pressure check and exhaust back pressure test to try and narrow it down.Is the check engine light on?

[Pappy]

Originally posted by wvspeedfreak
Sounds like either a fuel delivery problem or a possible catalytic converter restriction.Try a new fuel filter first like TRX450 said.If that doesn't help do a fuel pressure check and exhaust back pressure test to try and narrow it down.Is the check engine light on?

jason, whats that piece in the distributor that always goes out on chevy's:confused: for the life of me i cant remeber what it is but ive seen a ton of them go out

[wvspeedfreak]

The ignition module.

[bradley300]

now it wont start at all, i hadnt thought of a catalitic back up, but that could be it. it fires and tries to start, but cant quite do it.

i can hear the feul pump prime, so i dont think its a feul delivery issue, unless like someone mentioned, the feul filter is clogged

and yes, the check engine light is on

[bradley300]

Originally posted by TRX450RACER174
Try a fuel filter it should be on the left frame rail my 99 had a similar problem like that you would step on it and it would hesitate then if you eased into the throttle it was fine.

where at on the left frame rail? under the hood or, the bed towards the tank?

[TRX450RACER174]

Well mine was a 2wd xtra cab and it was on the inner frame rail under the cab about the middle of the door a round inline filter with flare fittings on the hard lines, i would think the 4wd would be similar hope that helps, FYI two months after i changed the filter the pump took a dump 350 bones from G.M. at cost plus 10%:mad:

[TRX450RACER174]

Originally posted by bradley300
now it wont start at all, i hadnt thought of a catalitic back up, but that could be it. it fires and tries to start, but cant quite do it.

i can hear the feul pump prime, so i dont think its a feul delivery issue, unless like someone mentioned, the feul filter is clogged

and yes, the check engine light is on

Sorry i didn't read this post until after i posted above, those trucks also have injector problems and G.M. had a extension to 10yrs 100,000 miles i know you are over in mileage but that could also be possible, another thing that could be the problem to is the wonderful plastic intake gaskets go bad alot also hopefully not that either but just information to thow out to you. Sorry if you were closer i would help you work on it i know those 5.7L like the back of my hand let me know what you come up with.
Erik

[bradley300]

well i need my truck tomorow so i'm stuck with parts i can get at wal-mart (its 1230 am here) so i got a feul filter, and found where you describe. i didnt have any starter fluid, but i had some brake kleen i sprayed in the intake and it wouldnt start, but it was alot closer than i had gotten without it, so a feul filter is sounding like more of a possibility, and walmart had one, so thats what i'm going to change out now, hopefully it works, thanks for the help!

[bradley300]

update: i also bought some actual starter fluid at walmart and just tried spraying it in the intake, and it fired right up. since i know the fuel pump is good (i can hear it prime) and since it will start with starter fluid, i can rule out the injectors correct? and since i'm spraying into the intake i'm bypassing the feul filter, so i would geuss that is what it is

[TRX450RACER174]

Well change it and let me know hopefully that is your problem, and no you can't rule out injectors becuase your just bypassing them with starting fluid they are not actually working yet try the filter and update me it's 10p.m. here right now i'm in SO CAL post up and i will check back every so often.

[bradley300]

it starts and runs now, but there must still be some issues elsewhere. before today it ran, but if you floored it, it wouldnt down shift and worked its way to about 3000 rpm, then started sputtering up to right at 4000 and held there, sputtering. now it will downshift again, rev quickly to 3500 or so and sputters to 4500, holds 4500 for a second and then upshifts to the next gear. i'm not sure what that problem could be, now it starts fine, idles smooth and has great throttle response again.

thanks for your help!

[TRX450RACER174]

Good deal if you need anymore help let me know, if it keeps doing the sputtering a little bit your pump might be going out also, the clogged filter puts alot of strain on the pump, try a bottle of marvel mystery oil in your next tank of gas or a bottle of atf it will help lubricate the pump and might give you some extra life out of it. If you have a mechanic friend in the area that has a fuel pressure gauge there is a service port on the rear of the manifold where the fuel line hooks up to the TBI unit, you can hook a pressure gauge to the port run the gauge on the cowl and tape it to the windshield so you can read the gauge and close the hood drive it around and see if it looses fuel pressure when it starts sputtering then you know for sure if you need a pump or not.

[bradley300]

i replaced the pump about 50,000 miles ago, how long should they last? and would the extra strain from the bad filter make it go out early?

[NacsMXer]

Originally posted by bradley300
i replaced the pump about 50,000 miles ago, how long should they last? and would the extra strain from the bad filter make it go out early?

It could likely be a dying fuel pump, and yes, a clogged fuel filter will strain the fuel system that much more in maintaining a smooth-running engine. I don't know if a clogged filter will prematurely wear out a fuel pump though, never heard of that.

My sister has a 2003 Chevy Malibu with about 55,000 on the clock, and I was surprised to see her fuel pump went out last week. She said she would give it gas, but it would sputter and just die out.....sounds like you have similar symptoms. Most likely fuel or ignition related it seems :ermm:

[TheIceMan]

You might want to check (replace) your fuel pressure regulator too.

[TRX450RACER174]

Originally posted by bradley300
i replaced the pump about 50,000 miles ago, how long should they last? and would the extra strain from the bad filter make it go out early?

Well i replaced the pump on my 99 at 66k or so but i firmly believe it was from the clogged filter that made the pump go out, do you notice any humming from the tank thats usually a sign that the pump is straining, a electric fuel pump operates at a constant pressure thats what the regulator is for, it bleeds off fuel to the return line at low rpm's where the fuel is not needed, so yes a clogged fuel filter can make a pump go bad it's putting extra strain on it trying to push the fuel through the clogged filter.

[bradley300]

it doesnt seem to make any noise except when you first turn the key you can hear it prime.

i thought the plugs and wires had fixxed the hard starting but i'm not sure it did now. it will not start the first time you turn the key. you have to turn the key, let it crank for asec, turn the key off, then try to start it again, then it fires up:confused:

i did the plugs and wires 1 at a time so i know they arent mixxed up

[KXRida]

Originally posted by bradley300
update: i also bought some actual starter fluid at walmart and just tried spraying it in the intake, and it fired right up. since i know the fuel pump is good (i can hear it prime) and since it will start with starter fluid, i can rule out the injectors correct? and since i'm spraying into the intake i'm bypassing the feul filter, so i would geuss that is what it is

just because you can hear it prime doesn't always mean you're getting fuel. If you have a clogged line, you're not getting anything. I'd get a fuel pressure gauge and make sure you're making pressure. As everyone said, fuel filter would be a good one to change. When starting it, turn the key to the on position a few times before starting it. If it fires after that, it sounds most likely fuel related because you said on the first key turn it won't fire, but on the second it will. Hope you get her figured out.

[chris46250r]

Originally posted by bradley300
i replaced the pump about 50,000 miles ago, how long should they last? and would the extra strain from the bad filter make it go out early?

So you have put at least 50K on this truck and you didn't know where the fuel filter was?

[monte433]

Check your fuel pressure first otherwise you will just be chasing your tail and throwing parts at it ,gm's have had pressure regulator and injector leaking problems both can cause hard starting and driveablity problems, so can too little fuel pressure from a weak fuel pump or plugged pickup sock.
If your pressure is good you can rule out pump and filter and look else where for your problem.
Also if you have a plugged cat. it will run better when cold and get worse as it gets warm unless it's completly plugged.

Leaking injectors and regulators usually will show a good amount of black smoke from the exhaust when it finally does start hope this helps.

[bradley300]

how much pressure will a good system be showing?