Thoughts on SOHC not being able to idle with low gas tank level.

[reallyfatbastard]

G

After warning my daughter repeatedly not to trust the gas gauge on a vehicle built in 1998, she ran it down to less than a quarter tank on the gauge. When I went to start it, to move it out of the way of my car, it would start every time, but would not idle on its own. I ended up having to keep one foot feathering the gas pedal and putting the other on the brake to shift out of park and then continue to give it gas or it would die. I figured that something else was wrong with the car and I'd be freezing my ass off soon working on it.

After she filled the gas tank up, it ran like a top. You can even reach in through the driver side window and start the car and it now idles like it was brand new.

There obviously was still gas in the tank or it would not have started and would not have kept running with my foot feathering the Gas peddle. Any thoughts on why a low gas tank would cause it to not idle on it's own?

Got a 2000 with SOHC 4.0 and had the same issue.Turned out to be the fuel pump.

 

[sandsprayer]

know that will have some of you shaking your heads, I'm not a big fan myself of just crossing your fingers and hoping, instead of fixing what needs to be fixed, that plan usually ends up biting you in your ass. If I see any more pump related issues before spring, that will force my hand, and I will have replace it then and there. But right now, I have visions of me having to suit up in my carharts, lying on my back on the ground in 30 degree weather, and snapping off a bolt on my daughter daily driver.

Outside of Vegas I'm not much of a gambler. However given your circumstances, would make that same bet!
30 degrees? not so bad. Wind and 30 degrees bad.
As a rule the tank should be kept above 1/2 during the cold months anyway.
May the Force be with you.

 

[jmirel2]

When you drop the tank, or pull your access panel off to replace your fuel pump, drain all the old fuel all out and make sure the inside of the tank is clean. I would suspect sediment or water is being picked up by the fuel pump at lower fuel levels.

 

[JohnH55]

After warning my daughter repeatedly not to trust the gas gauge on a vehicle built in 1998, she ran it down to less than a quarter tank on the gauge. When I went to start it, to move it out of the way of my car, it would start every time, but would not idle on its own. I ended up having to keep one foot feathering the gas pedal and putting the other on the brake to shift out of park and then continue to give it gas or it would die. I figured that something else was wrong with the car and I'd be freezing my ass off soon working on it.

After she filled the gas tank up, it ran like a top. You can even reach in through the driver side window and start the car and it now idles like it was brand new.

There obviously was still gas in the tank or it would not have started and would not have kept running with my foot feathering the Gas peddle. Any thoughts on why a low gas tank would cause it to not idle on it's own?

Just fuel pressure. I had this happen on my ranger it was low on gas and wasn't sucking up only gas, some air pockets got in and it lowering the pressure/ caused no constant fuel pressure. and causing it to stutter. Not to mention the other things in a gas tank that could have gotten sucked up. Before jumping to a new fuel pump or anything have the pressure tested at the fuel tank and at the fuel rail. Then if that comes back low at the tank you need a pump, if it's normal at the tank and low at the rail then there is a clog or restriction in the line or filter. I remember buying my explorer and the previous owner said they ran out of gas a lot, but now at 256k on the oem pump it never caused me a problem.

 

[FordMasTech86]

After warning my daughter repeatedly not to trust the gas gauge on a vehicle built in 1998, she ran it down to less than a quarter tank on the gauge. When I went to start it, to move it out of the way of my car, it would start every time, but would not idle on its own. I ended up having to keep one foot feathering the gas pedal and putting the other on the brake to shift out of park and then continue to give it gas or it would die. I figured that something else was wrong with the car and I'd be freezing my ass off soon working on it.

After she filled the gas tank up, it ran like a top. You can even reach in through the driver side window and start the car and it now idles like it was brand new.

There obviously was still gas in the tank or it would not have started and would not have kept running with my foot feathering the Gas peddle. Any thoughts on why a low gas tank would cause it to not idle on it's own?

Are we sure for 1 your fuel gauge is correct, if the sock under the pump is plugged or there is sediment in the bottom of the tank these issues can arise as well until more fuel is added, sounds like you need a new pump and your indication of the level thats actually there is not accurate. I've run into this with explorers as a dealer rech

 

[239]

My factory pump is still going at 280,000 miles. My tank gets down to about 1/8 or lower before I refill, and the pump is still good even after 21 scorching summers here in FL. I’ll admit I’ve let it get to the “check gauge” level before which isn’t good.

I am having an issue lately though where it’ll crank a lot when hot but stepping on the gas helps. It could be on its way out. But It’s yet to fail.

 

[Mbrooks420]

My factory pump is still going at 280,000 miles. My tank gets down to about 1/8 or lower before I refill, and the pump is still good even after 21 scorching summers here in FL. I’ll admit I’ve let it get to the “check gauge” level before which isn’t good.

I am having an issue lately though where it’ll crank a lot when hot but stepping on the gas helps. It could be on its way out. But It’s yet to fail.

I’ve seen the check gage light at least 50 times. It doesn’t hurt anything.

 

[239]

I’ve seen the check gage light at least 50 times. It doesn’t hurt anything.

I’ve read that if the fuel level gets too low it could pull sediment that’s at the bottom of the tank. But I don’t know how much that applies to our trucks.

 

[Mbrooks420]

The sediment would be there at every start up, and any time the truck sits idle for any amount of time. If you’ve got water or dirt in your tank it’s not going to be corrected by keeping more gas in the car.

 

[CDW6212R]

Ditto. There should not be any real amount of material in the fuel tank, unless the vehicle has been undriven for a long long time. With old age gasoline with alcohol in it does create problems, material inside the tank, and chemically alter the fuel. If it get very bad, the steel tank will break down and the surface will become corroded. Rust material will be produced, and that can foul the pump strainer, and the pump eventually. Other than that, driven regularly, there isn't anything in the gas tank to worry about.

 

[Larry Compton]

After warning my daughter repeatedly not to trust the gas gauge on a vehicle built in 1998, she ran it down to less than a quarter tank on the gauge. When I went to start it, to move it out of the way of my car, it would start every time, but would not idle on its own. I ended up having to keep one foot feathering the gas pedal and putting the other on the brake to shift out of park and then continue to give it gas or it would die. I figured that something else was wrong with the car and I'd be freezing my ass off soon working on it.

After she filled the gas tank up, it ran like a top. You can even reach in through the driver side window and start the car and it now idles like it was brand new.

There obviously was still gas in the tank or it would not have started and would not have kept running with my foot feathering the Gas peddle. Any thoughts on why a low gas tank would cause it to not idle on it's own?

There are 2 things that come to mind, either the pump could be sucking air when low or you could have a bad idle control valve that was stuck.

 

[CDW6212R]

True, the IAC should have been one of the first items to be cleaned if it's not almost new.

 

[sehaare]

There are 2 things that come to mind, either the pump could be sucking air when low or you could have a bad idle control valve that was stuck.

As soon as she filled up the tank it started and idled fine so I think that pretty much rules on the Idle control valve.

 

[CDW6212R]

When you are hunting for the cause of a problem, it's a good idea to be sure all maintenance items are taken care of. The IAC is not a forever never touch it part. It is something which should be cleaned any time there is any new idle issue, or whenever nothing else is more obvious or easy to do. The IAC can be cleaned in under 10 minutes.

 

[sandsprayer]

With old age gasoline with alcohol in it does create problems, material inside the tank, and chemically alter the fuel. If it get very bad, the steel tank will break down and the surface will become corroded.

Never looked @ it that way. Just always assumed the plastic tank came around because it is lighter and easier to shape

 

[CDW6212R]

I prefer the plastic tanks if they are strong enough. All steel tanks are in two pieces, and they can leak at the seam if the gas becomes really old and acidic. I think the steel tanks are much cheaper to make and easier to design with good mounting methods.

 

[sandsprayer]

and they can leak at the seam if the gas becomes really old and acidic

Roger that!
Anytime a tank is liberated from it's host give it a good clean and flush.
If it's metal, fill it w/ water to make sure no new leaks.
As far as expense goes, above my pay grade. However they have come a long way w/ blow molds.

 

[Josh P]

I like plastic gas tanks cause they never rust.

 

[sandsprayer]

I like plastic gas tanks cause they never rust.

Josh! Why you talking rust? Your in Arizona for Christs sake! Just bustin your balls a bit
Or chemically react as I have learned courtesy of @CDW6212R. Recall the olden times when fuel was gas?
I had a chance to ask about molds at one of the plants I service. The Chief Engineer showed me around and shared how easy his job has become.

Gotta love learning new things

 

[Therpwz]

After warning my daughter repeatedly not to trust the gas gauge on a vehicle built in 1998, she ran it down to less than a quarter tank on the gauge. When I went to start it, to move it out of the way of my car, it would start every time, but would not idle on its own. I ended up having to keep one foot feathering the gas pedal and putting the other on the brake to shift out of park and then continue to give it gas or it would die. I figured that something else was wrong with the car and I'd be freezing my ass off soon working on it.

After she filled the gas tank up, it ran like a top. You can even reach in through the driver side window and start the car and it now idles like it was brand new.

There obviously was still gas in the tank or it would not have started and would not have kept running with my foot feathering the Gas peddle. Any thoughts on why a low gas tank would cause it to not idle on it's own?