Horrible fuel consumption (6 mpg)..from14 to 6 rapidly.

[CMWebb]

My 1966 ram 1500 5.2 L has dropped from 13-14 mpg to about 6 mpg over last few mos. It idles fast some days and sputters and shudders on others. No fuel smell but only get about 100 mi / tank and I live far far in the boonies. I almost can't afford to drive it? What is likely the problem? Help please...thank you

 

[Hagar1]

My 1966 ram 1500 5.2 L has dropped from 13-14 mpg to about 6 mpg over last few mos. It idles fast some days and sputters and shudders on others. No fuel smell but only get about 100 mi / tank and I live far far in the boonies. I almost can't afford to drive it? What is likely the problem? Help please...thank you

1966???

 

[RamDiver]

1966??

The avatar show 1996.

.

 

[CMWebb]

The avatar show 1996.

.

Sorry..1996 Ram

 

[CMWebb]

The avatar show 1996.

.

Sorry ..it is 1996 Ram

 

[Yeret]

Is "Check Engine" light on? I've had all of your symptoms in my own truck at one point or another, and most were caused by something different. Funny thing is they didn't always trigger "Check Engine," but if the light is on, that's definitely the first place to start. If you don't have a diagnostic scanner, your local parts store should be able to scan it for you for free.

 

[CMWebb]

Occasional flickering of light but not stay on. Some people say that 6 mph is normal if riding around in pastures staying it "first gear" but I would think this would not be the case but I just don't know?

 

[Dusty]

Occasional flickering of light but not stay on. Some people say that 6 mph is normal if riding around in pastures staying it "first gear" but I would think this would not be the case but I just don't know?

The fuel consumption may be realistic for your driving environment, but spitting and sputtering is not. On a vehicle of that age (especially in Texas) I'd first check for a vacuum leak around rubber lines.

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, 18” wheels. Build Date: 3 June 2018. Now at 150003 miles.

 

[CMWebb]

After it warms up in about 5 min the sputtering goes away but the mileage idling along these paths is eating the gas up??Why?? would seem that with rpm being lower than driving that it would get better mileage?? Is 6-7 mph really the norm for this type usage??

 

[CMWebb]

Rubber lines look ok??

 

[DakotaFlyboy]

For a cheap fix attempt I would replace your PCV valve, easy to do 5 to $10 part. If it's stuck, I can't remember open or closed, it will cause terrible mileage.

 

[Marshall]

Occasional flickering of light but not stay on. Some people say that 6 mph is normal if riding around in pastures staying it "first gear" but I would think this would not be the case but I just don't know?

Well , what does it get on the road at 60mph?
riding around in the mud in first gear is a stupid way to figure out milage , of course its going to suck.
sitting at a red light you get 0 mpg. sure you are not using much gas idling around in first, but it takes forever to go a mile.

 

[B250]

I got about 7mpg from mine when the O2 sensor failed. Usually I get 13-14mpg. It also ran bad when cold because the O2 heater circuit didn't work. Then it just ran bad most of the time until I replaced the sensor.

My check engine light only comes on when it's time for the vehicle to self-destruct, BUT the stored codes can still be retrieved. The check engine light nay be on but the bulb may be loose hence the flickering.

The signal from the O2 sensor is tenths of a volt so all connectors and wiring must be good. On an older vehicle the connectors can corrode inside. Take them apart, clean them up and put some vaseline on the contacts. I even bend the pins slightly to make sure they make contact properly. Don't forget the connectors for the ECU aswell as they can be a bit shaky.

I was caught in heavy rain on a dirt road in Florida. The liquid mud got everywhere inside the engine compartment, which put the new O2 sensor on the fritz until I cleaned it all up again. Even the ambient air reference on the O2 sensor was blocked!

If it only runs bad at idle when cold another possibility is a faulty EGR valve.

 

[Daw14]

Have you pulled the spark plugs for a look ?

 

[Dean2]

Put an old fashion vacuum gauge on the engine and see what it reads. Stuck PCV valve, blown intake gasket, small cracks in vacuum lines that you can't see will all cause bad mileage. If your vacuum readings are normal, go to the next steps, like O2 sensors, Cat Converter, plugs, Map/MAF sensor etc..

Lots of stuff to check, just do it in an orderly fashion and keep good notes. You can't fix it sitting at the computer.

 

[Yeret]

A flickering CEL usually means a severe misfire. I've had it happen twice, first with a fouled batch of spark plugs due to a blown plenum gasket, and second, which was a bit tricky to figure out, turned out to be the ignition coil functioning fine when cold but began getting glitchy once it got hot.

 

[Dean2]

A bad batch of fuel can really screw up your mileage. Was driving a rental last month. It consistently got 28 mpg on the highway for the whole month. Ended up buying gas in the middle of nowhere South Dakota that was stored in a bad tank. After the fill the mileage dropped to 10 to12 mpg. It took three more fills to dilute that gas enough for the mileage to recover to 28 mpg, so bad gss can definitely be part of it.

 

[Dusty]

Some years ago I had an ATV that wouldn't even start because of bad gas. Took some out of the tank and it wouldn't even ignite with a match.

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, 18” wheels. Build Date: 3 June 2018. Now at 150303 miles.

 

[B250]

Now my Dodge has the same problem as CMWebb! Talk about jinxing!