Old Gas

[Cottontail]

I just bought a 1990 XJ...4.0...auto.

I know that it needed to be jumped as the neg battery cable is not getting good connection. When I test drove it on Saturday, it started right up. This afternoon, it wouldn't jump at all. It kind of sounded like it was flooded, but I am not sure you can flood a FI engine can you?

It cranked and cranked but wouldn't catch. Finally, I gave up and went and got a new battery. When I hooked it up, I jumped it and it fired up, ran really rough and as soon as I took my foot off the accellerator, it died. I did get it started one more time...this time without the jumper cables, but again it died after releasing the accellerator. After that it wouldn't start at all with or without cables. Incidently, the first jump with the new battery caused it to do some smoking from near the battery, but I couldn't quite figure where.

I know the new battery helped, because I could see a huge improvement in the interior lights, as well as the operation of the guages.

This leads me to believe it is fuel-related. The truck had only been run about a couple hundred miles in the last year and it is showing a half tank of fuel. The guy I bought it from probably started and ran it as much in the last week it was on sale as he did in the last 5 or 6 months!

I did a search to see what causes no starting on this truck and came up with: the Ignition module is bad, the Ballast Resistor is bad, the CPS is bad, the plugs are bad, the fuel pump is bad, the starter wire is loose, the neutral saftey switch is bad....

Is it possible that the gas is just bad? I've never driven or started a car with old/bad gas. What are the symptoms of that malady? What do I do to remedy it, just syphon and refill?

Any ideas would be great.

 

[5-90]

If fuel sits for a long time (think lawnmower,) it tends to lose the volatile hydrocarbons that make that wonderful smell of dead dinosaurs and gets the whole combustion thing going.

I'd try a little acetone or toluene to see if that can't kick-start running the fuel - especially since using a syphon always seems to be a pain with these things.

If that doesn't work, then things are REALLY crudded up! You'll probably want to pull the fuel pump and "sock filter" anyhow to make sure they're not clogged and clean them as well - the access is easy to get to (it's at the top front centre, if you haven't had to pull a fuel pump yet.) You can syphon through the open access port while you're checking everything else out.

As far as disposal of the fuel, you'll probably have to check with your local FD to get rid of the stuff.

5-90

 

[RichP]

If the fuel smells like varnish it's bad, bad gas has it's own unique smell. Another way to get it out w/o pulling the pump is to disconnect the fuel line at the fuel rail, temporily splice in 5 foot hose and turn the key on, let the pump pump the gas into some 5 gallon containers. Once you get down near empty dump a 5 gallon can of new gas in the tank and then watch the draining fuel, you will see a color change as the new stuff pumps thru.
Question I have is could you use acetone or that touluene stuff straight to act as a flush or would that damage the system.

 

[5-90]

Acetone is common in use as a fuel additive and as an octane booster, so that should not be any trouble.

Toluene was briefly used as a race fuel in pure form - since it's got an octane rating up around 140, as I recall. No trouble there. Toluene is also in common use as an additive and octant booster.

So, I don't see why they couldn't be used as a cleaner, since the odds are good they're in fuel already anyhow - most outfits are using them for octane blending, and they're present in fairly large quantities in avgas. Besides, they've never caused me any trouble (apart from the fact that toluene is getting difficult to find out here...)

5-90

 

[bajacalal]

The old gas, turns to gummy varnish stuff which will clog fuel filters and bugger up the injectors and pump. Contact with air, accelerates the decomposition of the gasoline, so I guess its rational that the fuel lines and filter held less oxidized gas, and it ran ok until the tank gas made its way up and it now runs poorly and the filter is plugged. It could have accumulated water if its rained and water has leaked in. I'd pop the fuel pump out, look at the pickup like mentioned, change the gas and replace the filter. If its better from there, I'd run a good shot of fuel system cleaner. Acetone is fine, it should help it fire up but I'd run some Redline or SeaFoam if its really gummed up, figuring these products are designed specifically to clean the system. I'm wondering if the jump diddn't fry any electronics, but you said it ran just fine at first so...

BTW 5-90, where have you bought toluene??? I have heard about how its an additive, but have never seen it sold straight.