Need some help on this one. 89 formula 305 TPI 5 speed, starts fine cold(first start of the day) Once it warms up, cranks long and idles rough. changed IAC, coil, ICM, ohm tested all injectors cold and hot, all at 16.7 to 17.0. All injectors pulsing as normal. Fuel pressure doesn't register until I actually turn the key, then it's normal. Once I turn off the car, fuel pressure drops fast, like, to 0 in less then 3 minutes. Once it does start, runs VERY rich.

If the car is running rich when restarting warm, check the fpr vacuum line for signs of fuel. You can cycle the key several times to prime the fuel rails and start pulling the plugs to look for wet plugs. the coil resistance can be good on injectors but you could still have a injector or two that the pentle is not stopping fuel flow into the cylinders.

forgot to mention that, I did check the vac hose on the FPR, bone dry. been checking oil for fuel contamination since Im not able to pull the fuel rail, and haven't found any fuel in the oil suggesting fuel leak down.

Just went out and checked again. cycled the key 6 times and still no fuel pressure until turning the motor over. Once running fuel pressure fluctuates between 40-42psi with FPR vac hose connected. Bleeds off as soon as I turn the key off.

is your starter old and/or heat soaked? do you have an alarm wired in?

No alarm, and starter cranks normal. Weird part about, it's not and issue where I can let it sit for 20 minutes and it'll be fine. I can let it sit for hours and it still acts up. I'm stuck at this point.

https://www.thirdgen.org/forums/tech...arts-cold.html

dude I had the exact same problem, and we have the same engine. First start of the day no problem then even after 8 hours at work the car wouldn't start. It was really hit or miss... I still don't know how I solved the issue. New plugs, wires, cap and rotor... all that came after we figured out it was the alarm. Difference is now I don't have to use this special bypass key that came with the car when I bought it. Good luck... lol

Thanks man, I've checked everything I can think of, still getting nowhere.

you said the fuel pressure doesn't raise until you actually crank... I believe it should be at optimal fuel pressure with the key in the on position. Fuel pressure regulator? Fuel pump?

Sounds like you have two issues. The ecm controls the fuel pump relay for the 2 second prime koeo.

Sounds like a crapped-out fuel pressure regulator (FPR).

If your FPR is old, you really should replace it.
The FPR has a diaphragm which absolutely will fail after the passage of time.
"Unexplained" starting difficulties is a common symptom of having waited too long to realize this.

When I turn the key, I can hear the relay click and the needle on the gauge jumps a little. once it starts, is 50 psi without the regulator connected, and 40-42 with the FPR connected. If I shut it off then turn the key back on, pressure builds no problem. Everything checks out on the pressure regulator, what gets me is that it doesn't hold pressure at all once the key is off. With no fuel contamination in the oil, I don't think its leaking injectors.

thanks everyone for your help. turns out I did have a tear in the FPR that I couldn't find without a second pair of eyes. fixed now. thanks again



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