engine is surging after new fuel pump

[924sownerga]

I have recently posted another question recently but would like help with this new issue. (Thanks for all the help in the past.)

After a 2 month non-running period I finally got the fuel pump replaced (with filter and tank screen). The good news is the car will start and run. The bad is it will not idle and if you hold the throttle open to about 1500 rpm the car surges up to 2000 rpm and then back down in about 1 to 2 second intervals. From a previous post I am looking to replace the fuel pressure regulator. I have read the fuel pressure regulator can make the car not run at all due to forcing the injectors to draw too many amps. Could this make the injectors fire too slowly causing the surges? I would also assume that the fuel pressure regulator to try to change first is the one at the back of the fuel rail, not the one in the front.

Has anyone used Sunrise Carburetors and Fuel Injectors, Inc. for refurbished injectors?

[Tidybuoy]

I'm not sure how the fuel pressure regulator could cause the inectors to draw too many amps - but an electrical guru may be able to answer that.

The fuel pressure regulator simply maintains pressuer in the system at a prescribed rate. The injectors simply open & close and if the fuel rail is pressurized correctly, a specific amount of fuel passes thru the injector nozzel. A bad fuel pressure regulator can definately cause erratic engine performance.

Besides the pressure regulator, there is the fuel damper which is basically a small pressurized fuel reserve that prevents surges in fuel rail (this is at the other end of the fuel rail). I replaced both on my car for about $125

Lastly, there is a fuel pump check valve (located at the end of the fuel pump). This is not going to cause erratic running problems but will cause hard starting if bad. The check valve is a one-way valve that prevents fuel from moving back into the tank after the engine is off. It keeps the fuel rail pressurized after the car is turned off. If this goes bad, the fuel pump will take some time to build pressure and thereby taking many more cranks of the engine before starting.

Hope this helps a little.

Vern

[idontknow]

From your description on the engine loping while running and not wanting to idle, I think you have a big vacuum leak.

Start by checking all your vacuum hoses and lines. Look for any cracks, loose connections, squeeze the hoses to see if they're brittle, anything.

I personally use the propane method of finding leaks if that step doesn't bare fruit. Just crack the valve open and methodically go over all parts of the engine while it's running till the engine surges and holds at the higher RPM. That should narrow your vacuum leak to whatever is wrong.

[924sownerga]

Thank you all for the great advice. Based on your recommendations I found a problem, thought it best to start a new thread with photos.

[Joakim]

Originally Posted by 924sownerga

Thank you all for the great advice. Based on your recommendations I found a problem, thought it best to start a new thread with photos.

So wheres the thread with photos?

[Rasta Monsta]

Originally Posted by Tidybuoy

I replaced both on my car for about $125

Where?