Stock fuel pump

[only"T"intown]

How much pressure should a stock fuel pump put out? Also, the fuel pump on my 84 has been dirrectly wired in to the fuse box (by the previous owner) so it comes on when you turn on the ignition and there isn't a regulater or relay on it. When the switch is turned on it sounds like it just binds down after it comes up to pressure until I try to start the car. The reason I am asking is that I bought the car not running and I have narrowed the problem down to a fuel problem but I just cant put my finger on it.
Thanks,

 

[BRAD_PADGETT]

Mine put out 39.9psi wirh a hot wire kit. Thanks- Brad

 

[Jerryl]

Fuel Pressure is only one variable of the fuel delivery equation.
A 40 PSI static fuel pressure reading is a function of the pump and regulator setting. In other words, if the pump can supply more then the 40, the regulator will max it out at 40 (Hose off).

The fuel pump may provide the static pressure a severely plugged fuel filter or collapsed sock (in the tank) may not allow sufficient flow.

The answer to your question is therefore "More than 40 if all is well"

 

[only"T"intown]

Fuel Pressure is only one variable of the fuel delivery equation.
A 40 PSI static fuel pressure reading is a function of the pump and regulator setting. In other words, if the pump can supply more then the 40, the regulator will max it out at 40 (Hose off).

The fuel pump may provide the static pressure a severely plugged fuel filter or collapsed sock (in the tank) may not allow sufficient flow.

The answer to your question is therefore "More than 40 if all is well"

So what should it produce if not regulated and what will that do to the injectors, pump etc...

 

[Jerryl]

According to GNTTYPE, you should see 34 -40 static (vacuum line removed)with the stock Bosh 233 regulator.

 

[only"T"intown]

Mine is holding at 35psi hotwired and no regulator. Is this enough for the stock injectors to fire.

 

[Jerryl]

Mine is holding at 35psi hotwired and no regulator. Is this enough for the stock injectors to fire.

Without a regulator, 35 psi is on the low side. You may want to verify the pump gets 12+ volts and/or verify the pump itself. There is also a small possibility of a collapsed "in tank filter".
When you state "No regulator, do you mean you removed the regulator and this is the "dead end pressure"?

 

[only"T"intown]

Without a regulator, 35 psi is on the low side. You may want to verify the pump gets 12+ volts and/or verify the pump itself. There is also a small possibility of a collapsed "in tank filter".
When you state "No regulator, do you mean you removed the regulator and this is the "dead end pressure"?

I'm not sure if it is regulated or not. The former owner straight wired the pump to the fuse block so I presume its getting a full 12 volts. When the key is turned to on and engine not started the pump sounds like it is pumping fast for a couple of seconds then the pressure builds rapidly and the pump sounds like it slows down alot and is under great strain.

 

[Jerryl]

The pump is working against the pressure.
It is HARD on the pump to work against the commonly known “dead pressure”.

I am not a pump/electric systems expert, but here is what I belief is happening;
The OEM set-up lets the pump run for a few (Not sure how many) seconds (Engine off, ignition on) and then shuts off. This ensures sufficient pressure but not wearing the pump down. If the car is started, the signal from the cam sensor (or crank sensor???) provides the "continue to run" signal to the relay through the ECM.

You want the pump to work a bit, as this implies it has sufficient capacity and pressure left in its capability. You may want to figure out the OEM wiring and get back to OEM set-up.

All in all, a bad explanation to a “good intention”.

 

[only"T"intown]

gracias.