mikal2000

i have a 90 fox 5.0 (trickflow top end, 24lb injectors, etc) i was driving to work this morning and while at idle the car died. it wasn't running rough or anything. i got the car the start about 20mins later and got down the road, another red light car died. 15mins later car started and I got it to my house. I replaced the fuel filter and let it run but it died and now won't start. I checked the cutoff switch and it is depressed. (That is correct, right?) I replaced the TFI (MSD Blaster) with no luck. I checked all fuses and none were blown, I can hear the fuel pump kick on when i turn on the ignition. I have a fuel pressure reg and it is set at 38psi, What should the pressure be when the ignition is just turned on? Should it be 38 then also? I believe the previous owner replaced the fuel pump with a 155lph pump. I am trying to confirm that at the moment. Any help will be appreciated.

1fast86

Do you have a gauge on the fuel line? If so onceyou turn the key and prime the pump you should be able to check full supply, over time the pressure will fall off. Crank the engine and see if the pressure is steady at idle, if not your fuel pump is going bad. You may also have vapor lock which is rare for EFI Mustangs but it happens. If it was runningnormal and then died andeverything looks good with the fuel then it will probablybea problem withignition system.

mikal2000

the couple of times i got it to crank it was maintainggood pressure, but now i can't seem to get it to start.

brentloftis

When you messed with the TFI did you move the timing forward or back at all?

mikal2000

negs, i didn't mess with the timing. still nothing.

brentloftis

If its not timing and your getting spark then I think it is fuel related. Try a couple shots of ether (starting fluid) down the TB and crank it see if it starts for a min, if so then it narrows down to the pump or injector pulse etc

FoxGT

When you say you replaced the TFI are you referring to the coil or the TFI module? I know msd makes tfi coils, but not tfi ignition modules. msd blaster's are types of coils.

Sounds like a bad TFI module 100% to me. They do exactly this & what causes it is the heat. Once the engine warms up, heat gets to it & it stops working. Letting it sit to cool for about 20 minutes & it will work again until it gets warm.

It looks like this & is on the distributor. It requires a tfi wrench to get it off (they're a couple bucks from parts stores)



^^ Is that what you replaced? ^^



Some parts stores can check it out for you to verify if it's good.