Carb Troubles? Mustang randomly runs like crap.

[AlexZi]

For a little while now Ive been having a hesitation when accelerating from a stop, probably due to issues with my accelerator pump. Im going to post up some vids I took, where you can hear that it just sucks air and doesn't respond when I hit the gas. At random times (Has happened about 4 times in a 6 month period) the car just runs like total crap. It takes long to accelerate to speeds that would be normally easy to get to. For example, it hesitates and takes long to get to like 30mph, but then it will act normal for a little, then take long to accelerate passed that. Its strange. I can push harder on the gas pedal but it will still accelerate at the same slow pace, but then get a random outburst of speed, and then go slow again. I found the best method of driving normally when this happens is to hit the gas pedal in short bursts. Probably a carb issue? The weird thing is this happens for about 1-3 days every time, then goes away on its own. Here are some vids I took when it was screwed up yesterday. And sorry if my explanation makes no sense, its just a hard problem to explain. You really have to drive it to understand what its like. In both videos the car stalls out. (In the first video, the first time I rev it stalls, and in the second video, the last time I rev it stalls out)

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[cprstreetmachines]

Makes sense, but sounds more like a fuel delivery problem. Like fuel pump. It'll accel in short bursts because you are probably drain the carb bowls. When you let off, it fills them back up until you hit the pedal again. That would be my initial guess.

[jonward786]

9/10 times a hesitation from a stop is fuel related

sounds like your fuel pump might be dying on ya

splice a fuel pressure gauge into your fuel line and drive around a little and watch the gauge. thats how we discovered my pump was done.

my only other thought is that you could have some blockage in your carb creating an intermittent lean condition. for the longest time i didnt realize that when my engine was backfiring out the exhaust when decelerating it was because i was running EXTREMELY lean (carb had a major block)...plugs were white as snow. rev the engine to about 3500, hold it for 3-5 seconds and then let off...if you have a backfire then ur not getting enough fuel.

[groho]

This may sound crazy, but how about rust in the fuel system. Rust will clog your primaries, and then eventually pass through the system. If you have a fuel filter, replace it. If you can pull the top of the carb and get to the carb bowls to clean them, do it.

[tx65coupe]

These old style tanks are prone to rusting out. If yours is original or just old. It may be the problem. To investigate you can remove the sending unit and use a flashlight and a mirror to look inside the tank.

My tank was new back in high school when I first got the Mustang road worthy again.

I just put a new tank in it, because it has been sitting for several years and the inside of the tank was trashed. The tank was drained and it has been in the garage this whole time and the tank still got ruined.

The tank is only 100 bucks and is not that hard to change out.

It could also be the fuel pump. Those are cheap, so you might try replacing it. I would inspect the inside of the tank first though.

[Mustangdemon67]

it might be fuel, but if not maybe its ignition. check for burned points or cracks in the spark plug wires, i had a similar issue

[bodyputtyless]

Don't overlook your ignition coil. A failing, or weak coil can cause these symtoms. Is there any backfiring through the carb opening? Thats also a sign that the coil is failing. I tell folks to start the car up at night and take a water spray bottle. set it to a fine mist and mist the coil. If the housing is breaking down they will see sparks jump off the coil body. Time to buy a new one. Other then that, I would suggest a simple check of the carb float. Check the screen that enters the carb for debri, and then make sure the float isn't hanging up. Fuel pumps either work or they don't. Floats can hang up or fail to "flaot" fromtime to time. Since your trouble is random, I'd look in that area. Keep it simple.

[kalli]

it's as if the engine is troubling whenever the pump is engaged.
you accellerate in the video and just at the moment when you let go off it actually starts accellerating. it is nearly in synch with the accellerator pump rod.

on->problem, off ok

i'd check on the obvious first. remove the air cleaner and check on top of carb if the choke is engaged. The upper butterfly should be fully open when the engine is warm. it nearly seems as it would be fully closed. then check with engine off accellerate like you do in the video and see if you get a good spray of fuel into the carb during the full turn off the throttle. it should start spraying with the slightest turn of throttle.

maybe just disconnect the rod for accellerator pump and redo the test to see if there is any difference

If that's all ok then I'd say as well fuel delivery problem. do you have a filter in there? a pressure gauge as recommended above might help. I'm with all the others. seems to be not getting fuel or it's choked.

what carb is it ? seems like autolite 2100/4100?!

[palerider]

Unfortunately could be a number of things. As some suggested start with simple (cheap) things first and work your way up. Fuel filter, coil, points, plugs, wires, carb, distrib. My car had similiar problems was fustrating but eventually ended up being the distributor. But replaced a lot of stuff along the way - it was due anyway. Becasue of the randomness of running like crap - I'm betting ignition related.

[tx65coupe]

A cheap thing would be to change the points and replace the fuel filter and see how it runs.

I would do it one at a time that way you might be able to narrow it down.

Usually my experience with coils is that they work or they don't, but it still could be the problem.