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Sea foam in gas tank

used seafoam in tank according to instructions, next day after driving for about 20 min on highway misfires and chugging. Following day same results. Changeing plugs and wires tomorrow… any other suggestions

What year and how many miles?


1991, 302
told the engine has about 40,000 (replaced engine)

Have you changed the fuel filter?


still have 3 quarter tank of gas…afraid to run it out for fear of engine damage. Should I try to run it out or syphon it before i change the filter? Have purchased fuel filter , plugs and wires in anticipation of having to change them all.

Change the filter first. It is possible the Seafoam emulsified some trash at the bottom of the gas tank and clogged the filter. If the filter is clogged, ‘running it out’ will not fix things. Replacing it should.

replace the filter before the gas with sea foam in it is out of the tank OR empty the tank then change it

If you don’t want gas pouring out while attempting to change out the fuel filter, you need a pair of pliers such as this. Clamp one on the rubber line before the fuel filter, and the other on the rubber line after the fuel filter.


change the fuel filter will let u know how it goes

Your truck is one of the infamous TFI-IV vehicles. Maybe the ignition module is going belly-up just like all the rest of them.

Heat is what does them in anyway and combined with August temperatures it may be pushed over the edge after 20 minutes of engine heating being applied to it.