YACT -- dear ATOT mechanics, wtf is wrong with my truck?

[xboxist]

1999 Chevy S-10, 2.2 liter, automatic pickup

For the past 2-3 months, starting my truck ranges from:

1) Turn ignition, giving it no gas, takes ~10-15 seconds of starter cranking to fire.

to

2) Same as above, except engine will not fire after 30(!) seconds of ignition-turning; have to HOLD the gas pedal to the floor and then it will slowly begin to start. A simple pedal tap or two does nothing. Have to hold it in completely before it will begin to start.

As you can see, some days it starts with some resistance, other days it starts with major resistance. Regardless, it should be starting within the first couple of seconds of ignition-turning. I fear I'm wearing out my starter with startups like this. The starter is only 6 months old.

So what's a likely reason? Fuel pump? Something more basic I could check? It's definitely not cold-weather related. It was 50 degrees this morning and it acted like 2) up above.

One additional note about this -- I noticed that the hard startups only occur in the morning (AKA after sitting all night). Restarting it during the day (like to go home from work) it will usually start fairly easily.

 

[Jeeebus]

I would take the truck into a "GARAGE" hint hint wink wink

 

[FoBoT]

http://forums.anandtech.com/ca...tid=85&flcache=6316208

 

[xboxist]

Well f-me... didn't even know that existed. Apologies. Should I repost there? Or does a mod move it for me?

 

[nakedfrog]

Got a voltmeter? I'd start with the battery.
Beyond that, how old are the plugs/wires/fuel filter?

 

[Anubis]

fuel pump

 

[exdeath]

Not the battery if its cranking that big hungry starter for that long. Ignition and long term fuel supply problems would also cause long term driveability issues after it's started, like acceleration stumbling or loss of power, not just when cranking. So need to think what affects startup conditions only.

Start by monitoring fuel pressure with a cheap pressure gauge to rule out pump, filter, or regulator issues. Is there relatively constant fuel pressure while cranking first thing in the morning? (it's normal for the needle to deflect slightly in tune with each injector pulse during cranking, but overall it should remain pretty constant)

Do you hear a relay click and/or the fuel pump when you turn the key on but don't crank? If not it could be the pump or relay failing to come on, or even the fuel pressure regulator. Mechanical devices like those tend to not actuate correctly in the extremities of their temperature range when they start failing and have a habit of making things seem fine after they are or have been warmed up recently. It's not unusual for mechanical things to 'stick' after sitting over night and work fine otherwise all day after the first start.

Also check fuel pressure when you turn the key off. It should hold for a fairly long amount of time and not drop off instantly or noticeably. Problems after sitting for a long time might be slow injector leak and flooding, requiring lots of cranking with the throttle held open to clear it out. Or the mechanical regulator relieving pressure when it's not supposed to and allowing fuel to be vaporized in the supply line, also causing long cranking time to flush it out on the next start. Do you smell excessive fuel when it doesn't start?

After you get it started in the morning with difficulty, idle it until its at full operating temp. Then shut it off for about 5 mins and try restarting it and see if it still gives you trouble. Could be the cold start enrichment temperature sensor, or still one of the aforementioned problems going into hiding after sufficient warm up.

A fuel pressure gauge can check for all the described fuel problems, and an ohm meter to check the temp sensor; are pretty much all you should need to get started. Or you can just throw money at it and replace one part at a time until it goes away, but thats the hard way

 

[Insane3D]

How long has it been since the fuel filter has been changed?

 

[xboxist]

Originally posted by: exdeath

Start by monitoring fuel pressure with a cheap pressure gauge to rule out pump, filter, or regulator issues. Is there relatively constant fuel pressure while cranking first thing in the morning?

Do you hear a relay click and/or the fuel pump when you turn the key on but don't crank? If not it could be the pump or relay failing to come on, or even the fuel pressure regulator. Mechanical devices like those tend to not actuate correctly in the extremities of their temperature range when they start failing and have a habit of making things seem fine after they are or have been warmed up recently. It's not unusual for mechanical things to 'stick' after sitting over night and work fine otherwise all day after the first start.

Also check fuel pressure when you turn the key off. It should hold for a fair amount of time and not drop off instantly. (problems after sitting for a long time might be slow injector leak and flooding, requiring lots of cranking with the throttle held open to clear it out)

After you get it started in the morning with difficulty, idle it until its at full operating temp. Then shut it off for about 5 mins and try restarting it and see if it still gives you trouble. Could be the cold start enrichment temperature sensor, or still one of the aforementioned problems going into hiding after sufficient warm up.

I thank you kindly for the detailed reponse!

-- I have no idea how to do the thing you suggest in the first quoted block of text. "Is there relatively constant fuel pressure while cranking first thing in the morning?" I... don't know. God I feel like a noob. How does one know this?

-- When you say to check fuel pressure, do you mean just by simply looking at your fuel gauge? If so, then I can't because my fuel gauge has not functioned properly for the past couple of years. I would have mentioned this in my OP had I thought it relevant. The gauge either shows fully empty (car off) or ful (car on).

-- Yes, it completely behaves the way you describe in the last quoted paragraph. After I get through the initial difficult start, it will typically start with ease for the remainder of the day.

--I'd have to dig out my paperwork but I think the fuel filter was last replaced ~2 years ago. Fuel pump has never been replaced. Battery was tested as "getting low, but still in the green" 2 months ago at my last oil change.

 

[JulesMaximus]

Originally posted by: nakedfrog
Got a voltmeter? I'd start with the battery.
Beyond that, how old are the plugs/wires/fuel filter?

If it's turning over for 30 seconds I doubt it's the battery.

When was the last time you had a tuneup? Is this a well maintained vehicle?

 

[exdeath]

Originally posted by: xboxist

Originally posted by: exdeath

Start by monitoring fuel pressure with a cheap pressure gauge to rule out pump, filter, or regulator issues. Is there relatively constant fuel pressure while cranking first thing in the morning?

Do you hear a relay click and/or the fuel pump when you turn the key on but don't crank? If not it could be the pump or relay failing to come on, or even the fuel pressure regulator. Mechanical devices like those tend to not actuate correctly in the extremities of their temperature range when they start failing and have a habit of making things seem fine after they are or have been warmed up recently. It's not unusual for mechanical things to 'stick' after sitting over night and work fine otherwise all day after the first start.

Also check fuel pressure when you turn the key off. It should hold for a fair amount of time and not drop off instantly. (problems after sitting for a long time might be slow injector leak and flooding, requiring lots of cranking with the throttle held open to clear it out)

After you get it started in the morning with difficulty, idle it until its at full operating temp. Then shut it off for about 5 mins and try restarting it and see if it still gives you trouble. Could be the cold start enrichment temperature sensor, or still one of the aforementioned problems going into hiding after sufficient warm up.

I thank you kindly for the detailed reponse!

-- I have no idea how to do the thing you suggest in the first quoted block of text. "Is there relatively constant fuel pressure while cranking first thing in the morning?" I... don't know. God I feel like a noob. How does one know this?

-- When you say to check fuel pressure, do you mean just by simply looking at your fuel gauge? If so, then I can't because my fuel gauge has not functioned properly for the past couple of years. I would have mentioned this in my OP had I thought it relevant. The gauge either shows fully empty (car off) or ful (car on).

-- Yes, it completely behaves the way you describe in the last quoted paragraph. After I get through the initial difficult start, it will typically start with ease for the remainder of the day.

--I'd have to dig out my paperwork but I think the fuel filter was last replaced ~2 years ago. Fuel pump has never been replaced. Battery was tested as "getting low, but still in the green" 2 months ago at my last oil change.

To check fuel pressure you need an external dial gauge that is very similar to a tire pressure gauge. It attaches to a valve stem on the fuel rails. It's supposed to hold a constant pressure at all times, even when the key is off. Consult manufacturer documentation for appropriate pressure, usually its 20+ psi.

I apologize for being over technical, I assume that people coming here know a tiny bit about their car already are looking to try their hand at troubleshooting otherwise there is no point in asking on a forum for help only for everyone to say "take it to a mechanic" since thats obvious if you're not doing it yourself

Sorry, I tend to be edit happy, I've added a few things since you quoted.

Is there a strong fuel smell when cranking when you have trouble starting it? If so, I strongly suspect fuel pressure regulator.

 

[LTC8K6]

When you first turn the key on, the fuel pump should run for a few seconds to pressurize the lines. If you listen carefully, you should hear this happen. The pump should run for a bit and then shut off.

You might try giving the fuel pump some extra time to build pressure by turning the key to on and then off a couple of times before you try to start the engine. Leave the key on for a few seconds each time, and then try to start the engine.

 

[marincounty]

Sounds like it could be a problem with the low speed mixture. Fuel injected?
My sister had a similar problem with her Toyota pickup. She went around and around with the dealer until they finally diagnosed the problem.