Car statred running bad suddenly

[mgood]

Car is a 76 - 280 totally stock and was running great, no problems at all. I have a car show next week to go to and wanted to clean the car up a bit, so I got it home and worked on it (cleaning up) and add two 5 gallon cans of gas that I have had for about 3 mo. to the gas in the car , made almost a full tank.

Took the neighbor for a quick trip around the park and dropped him off and want to take the car back to the garage I keep it in. This is when every thing when crazy. The car started to juke and buck as I accelerated until it just would quit running. It would restart and run for about a minute and do the same thing. I finally got out of the car in a parking lot and got it started and kept it running by burping the throttle, drove it about a 1/2 mile and it just died. Got it restarted and drove it the last mile to the garage and parked it in the drive and it idled fine until I parked in the garage.

My question is could it be from some water in the gas from the cans I pored in it? I do use gas stabilizer and I pored some in when I garaged the car.

I just ordered a fuel pressure gauge an will install it next weekend to check the pressure.

Some ideas would be great on the cause.

I have never experienced anything like this before.

Thanks Mike.

[240260280z]

Check the spark plugs to see of they are black and sooty and report back.

[ajmcforester]

Check the fuel filter if it isn't clear enough to look thru try a new one you might have some rust or something in the tank.

[Zed Head]

How big is the park and what was the drive like? Were you showing the neighbor what the car would, with some high RPM stuff or was it just a mellow three or four block trip?

Were it me I might drain the tank contents, change the filter, and refill with new gas, just to take that variable out of the picture. You can use the fuel pump to drain the tank by running a hose from the filter to your portable tanks, removing the solenoid wire and turning the key to Start.

As far as other sources, what was the tachometer needle doing while the bucking was happening? If it was moving faster than the crankshaft could possibly move, jumping and/or reading abnormally high, you might have an ignition system problem, maybe the module.

[siteunseen]

Get a new fuel filter.

[mgood]

OK guys I did some checking just 15 minutes ago.

The car started and idled with out any problems, I had to move it a couple of feet over so I backed it up and over a very short distance and it ran normal.

Blue - all the spark plugs are even in color and a dark black. Not sure if this is normal for my car or not. I have not looked at the plugs for over 10 years.

AJ / siteunseen - I removed the fuel filter, probably the original to the car and a lot of rusty colored gas ran out the bottom. I am going to buy a new one.

Zed - The park drive was about 4 miles and not very energetic at all. It was just a drive through the park witch is 200 yard from my home. Got the car up to around 4K for shifting.

The tack was not doing anything crazy seemed to move with the speed of the engine.

I might have to drain the tank, where is the solenoid wire located?

Thanks for the help, I will not be able to work on the car till Friday.

Mike

[ajmcforester]

Rusty gas is bad. This does not need to be done right away and finding a place takes a while. You need to get the gas tank boiled out to remove the rust. Do not put that sealer stuff in the tank with ethanol and all that other garbage they put in gas now days it will come off and make a bigger mess than doing nothing. What I do and it works is every oil change dump one quart of non-detergent motor oil in with a 1/4 or less filled tank, drive hard enough to slosh it around and fill the tank. I know people that do the oil trick with cars over 40 years old and when you look into the tank with a flashlight you see shiny metal.

Until you get the tank boiled you might want to get 2 or more filters while at the store, they will plug up quick. Also check any screens on the fuel system the 240z have ones on the carbs and my 200sx had one before the fuel rail I do not know if a screen is on a 75 z car.

I bet you take care of the tank and you're current problem will be gone.

Now the black plugs. Once you fix the fuel tank issue, I'd recommend replacing the plugs, and see after about 3-4 hours of use, pull the plugs and see if they are getting black. Black plugs are not a good sign and might mean another problem, but you want to fix the problems you know and then see if you are still getting black plugs.

[djwarner]

Cold engines run rich and will build up a carbon coating quickly. Checking the plugs before you moved the car would tell us more, but that's in the past now. Does sound like a fouled gas filter though.

[Zed Head]

Where there's rust there was/is water. Could be that you just have a puddle of separated water at the bottom of the tank and some sloshed over to the tank outlet. If you haven't looked at your plugs in ten years, I'm going to guess that this not a daily driver. Does it sit for quite a while between drives? Today's ethanol-containing gas will suck up water pretty quickly if it can. Are your charcoal canister and gas cap intact, to keep the tank sealed from the atmosphere?

[240260280z]

Black plugs means running rich. Check the water temp sensor and associated wiring.

If you drive again, bring a can of carb cleaner and a spark plug wrench as you will keep fouling up the plugs and it may not run again until you clean them.

I had this happen to me once when the connector too the water temp sensor came off.

Have a look here for info about what I am talking about:

http://www.atlanticz.ca/zclub/techtips/runningrich/index.html

Check the pigtail connections too.

[FastWoman]

My question is could it be from some water in the gas from the cans I pored in it?

Could be! Once when I evacuated before a hurricane, I hauled my lawn tractor to high ground atop a flat-bed trailer. It sat out the hurricane in the rain. I didn't notice there was a crack in the gas cap, and water dribbled into the tank. I was cleaning chewing gum out of the tractor for over a year after that. I went through maybe four changes of filters and 3 carb clean-outs before the poor tractor forgave me and ran right again. There is nothing quite so evil as bad gas!

Black, sooty plugs don't sound right, even after a cold start. I'd check the connection at the coolant temp sensor.

[mgood]

Zed, my system the charcoal canister and gas cap are very intact, when I open the gas cap there is usually positive pressure in the system.

Blue, I know I run a little rich, I will check the connectors that you showed in your techtips. I think my AFM is a little off.

I will not be able to do anything till Friday, but I will get back to you all, thanks for the help. I just assumed that my car might be immune to any real problems, guess not.

thanks Mike.