Quick reference. 250 cid straight six, 2door. After some cleaning, rewiring and some TLC the maverick is finally starting to take shape. (pics soon!). I fixed the "starting on its own/staying on when the key is off" issue with a new starter solenoid. I owe thanks to all of you for that one (of course after some long engine inspections looking at everything mentioned!). Next issue that was fixed was my silly low power issue, aka the "I don't feel like completely turning over or electrically working correctly" issue. The fix? New battery. Everything works just peachy now! Onto my simple questions. First of all the intake on the carb looks like it's dirty (black gunk, pretty thin, on select areas). My guesses based on what I've read is that it could be soot or something foul with the gas tank. This questions leads me to the last issue, engine pulsing. Is it a possibility that rust in the gas tank/foul fuel filter/soot/or a combination of all of those could cause pulsing loss of power after 20 or so minutes of driving? Of course there is one more potential reason is heat, I had a 02 ford focus that had a coolant leak. I didn't notice, it overheated and started pulsing on the freeway. Needless to say new waterpump fixed the problem. Unfortunately the mav doesn't leak coolant, doesn't leak anything for that matter. Another reason I want to think fuel is when I turn it on it tends to want to die a few second later unless I rev it a bit (few seconds or so) and it will just be happy sitting there idling. Once again you all are the best thing that ever happened to my maverick, can't thank you all enough for what you've done so far!
Rust from the tank can and will cause pulsing from the engine staving for fuel. I just changed the inline filter on my 77 last weekend. Sumbitch was full of rust. That's how I knew the filter needed changing...................the engine started to stall in around town cruising.
When does it pulse? After 1970 car makers leaned the mixtures down for emissions and I have had to go one or two sizes larger on the main jet(s) to get the engine to maintain freeway speeds without the car cycling between 50 and 65 mph constantly. Rust in the tank can certainly cause the mixture to lean out. So can a ruptured vacuum advance unit, over/ under advanced timing and a weak fuel pump. Check your timing at 3500 RPM, check to see if the vacuum unit will hold a vacuum, check to see if your pump pressure is correct and if it bleeds down. (some pumps have a return but if yours has only two lines it should hold pressure) If the float level is too low it can be a big factor too but if the carb was not recently rebuilt it is not likely to be that. Check your distributors advance plate for wear at the pivot pin. A worn plate can cause enough change in dwell to even stop the engine but the first signs are surging or intermittent loss of power with a return of it moments later. This resembles a surge. I hope you find the problem - check it all out before spending money to replace things that might not be the cause.
