My 87 Iroc is not starting, turn key, fuel pump prime for 2-3 seconds and then stops with pressure around 10 lbs.

I removed the fuel line and stuck it in a bottle and turn on key, fuel pump primes sending fuel and then stops.

Any one encountered this or have a solution? The fuel pump and filter are new and had been working a couple of days ago.

thanks in advance.

 

That's how it works, it doesn't run continuously until the engine is running. The ECM will turn the pump back on when it senses the engine firing, or when oil pressure builds the bypass will turn it on. That 10PSI though..... that's something to worry about.

 

Now realizing problem is due to low pressure.

I have new Walbro 255 that was working fine, new fuel filter, new pressure regulator. I am at a loss here how the pressure can only reach 10 PSI then drop to zero soon after.

Are there any tests I can run before having to drop the tank?

thanks

 

I assume your 87 Iroc has a TPI engine? If so then your fuel pressure at the schrader valve should be near 40 psi. I installed a new Walbro fuel pump then had the plastic piece on the end dislodged and occlude the fuel line in the tank (the short piece of rubber hose which connects the pump to the metal fuel line). I'm not sure that is your problem, but if car previously worked, but now doesn't work after changing the fuel pump it seems a logical place to start looking for the problem.

 

ya dude, i agree with above. DID you reuse your pump pulsator> i upgrade the connection from the pump to the hard lines using a neoprene fuel injection hose. I would try clamping the return line and see if the pressure stays, if it doesnt its your sending line, most likely the fuel pulsator. I doubt its a stuck injector. peace. ull get it

 

I removed the fuel line from the fuel rail and ran the fuel pump from a 12V source and pump continue to send fuel.
Then I reconnected the feed line and disconnected the return line. Again added power source and pump continued to run but nothing came out of the return line.

Where was all my fuel going if it was not going back in return line?

 

If you are not getting 43psi at the rail ,the regulator won't open up to bypass the fuel back to the tank
Back to checking why you have low line pressure .As mentioned above you may have a leak in the tank between pump and hard line which is bleeding pressure off when the line loads up.

 

Thanks for suggestions. Guess I will start on the dreaded dropping of the fuel tank.

 

If it's not building sufficient pressure and it's not flowing through to the return line then the pump is dead headed at the reg, (which was already pointed out by VetteOZ) if it's not the coupling hose or the pulsator then the check valve in the pump outlet is missing, or bad.

The ALDL diagnostic connector pin "G" can be connected to 12v with the ignition off for testing, or draining the tank.