Engine hesitation

96 Vortec · May 23, 2003

Engine hesitation

Just recently I have had a little trouble with my engine starting. It turns over fine but doesn't always start right up. Usually if I let it turn over a couple times and release the key, then turn it again, it fires right up.

For the past several months I have had a problem with a little engine hesitation. When the engine is cold it starts fine, with the occasional occurance of the above mentioned problem. I let the truck idle for a couple seconds and then put it in gear. So far there is no problem. After the truck is in gear I give it a little gas and the whole truck shudders and hesitates for a second. Then it picks up and drives normal. It won't do it again until the truck parked long enough for the engine to completely cool down.

In the last 5k miles I have replaced the intake manifold gaskets and all four oxygen sensors. However the hesitation had been occuring before I performed any work on the truck.

Anyone got any ideas what I should be looking to fix or replace?

Oh yeah, this is on a 96 K1500 w/98500 miles.

BadBowtie · May 23, 2003

The cranking and not firing right away signals me to think about the fuel pump. also check the TPS (you know you need a coversheet on its report ) It could be bad, my 91 does the same thing, and the TPS wasnt reading correctly, if you mash it, it would be fine, it seemed to have a 'flat spot' in the potentiometer.

-John

AZ-Z71 · May 23, 2003

TPS report.....hahahahaha

You didn't get the memo, I'll send you another memo.......

BadBowtie · May 24, 2003

HAHA good you got it, I thought it was funny!

96 Vortec- Do you have an update on the situation? Is there anything else that it does, at a certain time, temp, any more specifics like that?

-John

Fishhunter911 · May 24, 2003

when was the last time you did a full tune-up??? I had the same problem... changed cap,rotor plugs wires,fuel filter,pcv valve and it all went away.. runs like it is brand new

Silverstanger · May 24, 2003

why won't anyone help me with my engine hesitation.. mine is worse than that.

when it is cold and even after it warms up sometimes and sometimes not.. it falls on its face when i mash it to the floor and sputters and almost dies and then goes..

it sputs a whole lot more the colder it is.

Is that lack of gas??

BadBowtie · May 25, 2003

That sounds very similar to what mine did. If you mash the gas fast, does it just take off? If so, I'd say replace your TPS [report]

96 Vortec · May 27, 2003

Silverstanger - Have you changed your fuel filter? Mine acted the same way when the fuel filter was clogged. I couldn't run under full throttle and had a lot of power loss.

BadBowtie - The problem only occurs when the engine is cold. It only happens when I first put it in gear. It will give one hesitation and then drives normal. It won't do it again until the engine is completely cold again.

I did my 100,000 mile tune up at 70,000 miles on the 5 year mark. I didn't change the plug wires cause I didn't have the $100 to drop on them at the time. After all, the cap, rotor and plugs where already in the $90 range.

I spoke with someone who suggested that since my problem only occurs when the engine is cold that I have a crack in the distributor cap. I'm gonna pull it off tonight to check it out.

MarkD · May 27, 2003

BTW, did you get the memo on TPS coversheets? (boss #7 chiming in after returning from vacation)

I would point toward a couple of areas:

Fuel: How old is your fuel filter?

How often have you run your fuel tank very low?

Have you re-routed your fuel line near heat?

Is your IAC valve/throttlebody clean?

Ignition: New plugs?

New Distributor cap? (are you distributor-less0

Bad Coil (when it gets hot) (cheap fix)

Where do you live?

96 Vortec · May 27, 2003

Fuel filter is 8 months old

I have a 26 gallon tank and I run 20 gallons out of it each week.

Haven't re-routed fuel line because I have no problems running when the engine is warm.

What is the IAC valve?

Plugs have 20,000 miles on them as do the Cap and Rotor.

I plan to check the cap and rotor when I get home tonight.

This problem only occurs when the engine is cold

Wingnut · May 27, 2003

Yeaaaah.....We're putting new cover sheets on the TPS reports now....M'kay?

While you at it....We're going to need you to work SSSSunday...M'kay?

EMC'S Z · May 28, 2003

My 97 5.7 does the same thing. Let me know what you find out. I have a new cap, rotor, wires, plugs, and fuel filter. It does the exact same thing. ONLY when stone cold and only that first or second gassing. 125000 miles