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itbrokeagain
11-22-2008, 12:08 PM
Low speeds are fine. Get it onto the highway and push any more than ½ throttle and it seems like it is loading up and backfiresd a lot. Bad vaccum advance????

78 F-150 351m T-18

Thanks!
mike shelton
11-22-2008, 01:35 PM
low fuel prussure? !!!!!!!!!!
JasonCJ7
11-22-2008, 10:59 PM
Check your fuel pump and fuel filter.
itbrokeagain
12-30-2008, 12:19 PM
Getting plenty of fuel. Took the ignition box to Autozone and they tested it and it came up as bad. Changed it and it is doing the exact same thing.

At lower RPM it runs very well. At higher, getting on the highway or getting ready to change gears, it cuts out and backfires. As soon as I get off the gas it runs fine.

Arrrrrrrrrrrg. :mad:
eighty3bronco
12-30-2008, 07:36 PM
Almost sounds like timing to me but could it be getting too much fuel and is choking it out? What does it act like without driving and you rev the engine?
itbrokeagain
12-31-2008, 01:59 AM
No problem. Only acts up under a load
eighty3bronco
12-31-2008, 03:27 AM
have you checked the vaccuum at all? Check the spark plugs. I think I had that problem with my 302 at some point and it may have been the plugs.