hi guys well the sho still wont run without starting fluid my injectors dont seem to be working for some reason after a engine swap. my fuel pressure is at 70 to 80 psi when pump is running when you first turn on the switch and when you are trying to start, when the pump stops the pressure drops to about 35 or 40 psi and then starts a steady drop to 20 and after about a min its down to 0. I also got a set of noid lights to check if the signal is getting to the injectors, the only light in the kit that woul fit my injector plug was the on for gm tpi but it did flash while i was trying to start it. I also have removed the intake to see if the injectors where working at all , i grounded everything with the intake up enough to see if they where working and with the noid light pluged in just to make sure i was getting power and they where getting the signal but never shot or even driped any gas i am now waiting on new intake gaskets to come and im gonna put the fuel rail and injectors off my old engine in just to besure. i also have changed the cps,icm,fuel regulator and checked every ground i can find if you guys can think of anything please let me know. also the car will run as long as you keep spraying it with starting fluid but soon as you stop it stops
Sounds like a bad PCM. Either that or the injectors are not connected correctly to the PCM.
But... You did say the light flashed while you were cranking which means that the injectors are opening and closing correctly?
If they aren't even wet then my best guess is that the fuel isn't getting to the injectors. 70-80psi is really high. The pressure also shouldn't drop that fast.
I don't understand how return/returnless fuel systems work, but it sounds to me like the fuel is going straight back into the tank if its return or is just stuck at the rail before it hits the injectors if its returnless.
What swap did you do? What year car to what year motor? What motor was in originally? Did you bring the PCM over with the new motor?
Returnless system is similar with the return line system - difference is that the regulator is inside the tank and dumps back the fuel inside the tank.
A check valve inside fuel pump keeps the pressure from going back into tank when power is turned off, but it will go eventually down to zero after a while (hours?).
the engine came from a 92 sho mtx just like mine same year yamaha 3.0 . the only thing different fuel wise now from before i changed engines is im using the fuel rail and injectors that were on the engine i bought thats why im gonna try using the rail and injectors off of mine. I dont think there is anything wrong with my pcm but anything came happen i guess. my car was running before the engine swap but had a cracked head . it ran pretty good other than pushing the water out the overflow constantly and the smell of exhaust in my rad. Keep giving me ideas guys and i will keep trying them thanks
Is the '92 SHO fuel system returnless? I was under the impression that it wasn't just based on the vintage. Like I said before, you should never be able to get 80 psi in the rail, so something is allowing too much pressure to build like a clogged return line.
Could you try running like 20 psi of air into the return line to see if it's clogged or not?