imnotmy77stang

ok, i just got this thing back together after buying it in disrepair and doing a valve job to fix a burnt valve. (its a 1.3 L 4 cyl, the big brother to the 1.0 3 cyl - same engine design). i put in a new fuel filter, new air filter, fresh oil change, new plugs properly gapped, new wires, new cap and rotor, new pcv valve, basically every damn thing is new. i also ended up putting in a brand new gas tank and a used fuel pump / pickup assembly cause my stuff was shot.

well, first the fuel pump wasnt working. i took it back out and after some PB blaster and some bench time it seemed to work ok. i let it pump about 3 or 4 gallons of gas thru it to make sure it was gonna stay working and it went back into the tank. so..... i go to start this thing and it wont fire up. the damn thing had fuel pressure to the injector (yeah it only has one) but it wasnt spraying. i took the injector out and it looked ok, i hooked it up and could feel it pulsing when the motor was being cranked over so i put the injector back in.

bingo it starts (barely). well, the gas i put back in it was about 50/50 fresh/old so i figured this is why it was running like crap. i limp it to the gas station and put 30 bucks of fresh gas in it, at this point it should be about 10 or 11 gallons of fresh to 1 or 2 gallons of old (certainly should run pretty good). still, it runs like absolute crap. i have to press the pedal just the slightest bit to get any kind of accelleration, any further and it just falls on its face - yet when i back off the pedal it has a sudden small surge of power. basically i drove it home from the station by pumping the gas the whole way and every time i let off it gets a little burst of energy.

could it be the fuel pressure is too low? could the injector be half-*** clogged? could it be a throttle position sensor? im pretty frustrated with this thing at this point - its really been a bigger piece of crap than it was supposed to be.

67mustang302

Could be a clog, could be sensors too. TPS, MAP etc. Try and find out what the resistance/voltage the sensors are supposed to be and test them with a multimeter. That piece ain't even OBD I is it?

imnotmy77stang

i dunno when OBD I started, but this piece of crap is a 91.

im thinking its either the injector, fuel pressure, or TPS but i wish i had a better way to narrow it down before i hit the autoparts store on tuesday

Stepman

Well, to me, if you let off (cut air) and it runs better, you are either low on fuel pressure or weak injector. No telling though after the pb blaster....check pressure. if that's ok, replace injector?