Car losing speed and bucks when accelerator is applied

[gopiqpp]

My '88 GM wagon was running fine till today when it stated losing engine speed and jerked if given throttle to increase speed.Happened about 70 km after filling the tank.If foot was taken off the gas pedal it would smoothen out and run at about 30km/hr speed. Any attempt at acceleration would cause jerking.It idles normally except for a slight miss now and then(always had that problem). After reaching home and switching off it wouldnt start again but engine cranks. I depressed the little stem in the fuel pressure valve with key on and there was a good strong spurt.
Could this be a choked fuel filter problem , hence the bucking when accelerator is depressed ?
Thanks
Dr Gopi

[Nathan in MI]

When is the last time your fuel filter was replaced?

[Tiggie]

Could be fuel pressure. Buy a cheap tire gauge and use it on the stem you squirted fuel out of earlier (this will ruin the gauge for later use, so don't use a good one). I think you are looking for ~35psi without the car running, someone correct me if I'm wrong. Check the fuel filter if it's low. Has the car been sitting?

You might also have too much fuel pressure if the fuel pressure regulator has failed. Was it smoking any or did the exhaust smell different? Try holding the gas pedal to the floor while cranking the car over. This will tell the computer not to fire the injectors and get all the extra fuel out of the cylinders.

Might just be water in the gas. STP Gas Treatment will fix that.

Since it's not starting now, check the fuel (see above), spark, and air. If it's got spark and the right amount of fuel, I want to lean towards a faulty TPS. The IAC won't open if the computer is getting a thottle signal and it won't get any air to start the car. Try giving the car a little gas while cranking it over if you get to this point.

I'm sure someone else will reply shortly with some better suggestions. EFI isn't my strong point.

My ma's '87 5.0 T-Bird has a bucking problem for about a minute, three minutes into start up. It's dead consistant and no one knows what's wrong with it!

[gadget73]

Could be a clogged filter. Since it happened right after getting gas, you might have gotten a bad load of fuel that clogged up the filter, or it might just be bad gas.

[gopiqpp]

When is the last time your fuel filter was replaced?

Never, I guess( I got the car a year ago but the previous owner did not care too much as long as the car worked OK 1)

[gopiqpp]

Thanks guys for the advice. I will replace the fuel filter and add STP Gas Treatment as the first step and will keep you posted.
I just remembered something: A week ago when I topped up my half full tank and started the car the 'low fuel' warning light came on briefly and went out after a couple of seconds. It has never come on before this. Is this of any significance ?

[gadget73]

not likely, the connections get dirty on the low fuel module and the light will start coming on randomly. If it gets annoying, the module is a small black thing located under the dash near the accelerator. It says "low fuel module" or something similar on it. Unplug it, and plug it back in. Usually this fixes the problem.

[gopiqpp]

Changed the Fuel Filter and plugs (all the old plugs looked good though),and the car is its old self again with a nice smooth pickup upto 80 mph.Seems to have a tad more power now that the engine isnt pulling the AC and smog pump (for the time being till I get the belt).The low fuel warning lamp hasnt come on again either.Thanks for the help.