Fuel pump or fpr going bad?

[UrN2nd]

I've been on ecmlink forums and we figured out what's goin on but now I gotta narrow it down a lil more.



Ok my car runs good for about 10 mins. Then starts cutting out. My fuel pressure is base at 43.5. After 10 mins my fuel pressure drops to 25 psi. When I rev up the engine and it boosts my fuel pressure drops to about 5psi. After a good long run the fuel pressure drops to about 3 psi. If I pinch the return line my fuel pressure climbs up to 60ish. I have a aeromotive fpr and a 255. My 255 whine louder then anything in this world. I pulled the pump and changed the filter on the pump and replaced the Oring for the pump output. I have a clean serviceable hi flow filter. I have opened up the afpr but found nothin that I can't tell wrong with it. But I'm not sure which one is my problem. I have a new pump coming anyways. But does this sound like a fuel pump problem or an afpr problem?

 

[Soccerguy136]

When you set your base fuel pressure, the vacuum port is disconnected right?

How do you know what the fuel pressure is when you are boosting. Do you have a gauge in cabin?

If it's just sitting there in neutral, revving the engine is not going to build boost. Turbos only build boost when there is a load on the engine.

 

[delta448]

If I pinch the return line my fuel pressure climbs up to 60ish.

Quickly? That means the pump is working fine.

How did you set base pressure?
How much vacuum do you see at warm idle, and what speed does it idle at?

 

[99gst_racer]

Have you checked/replaced the post filter?

Also, disassemble the regulator and check under the diaphram to make sure it was properly machined.

Aeromotive adjustable fuel pressure regulater issues

 

[c2ypt1c]

My 255 whine louder then anything in this world. does this sound like a fuel pump problem?

YES

 

[delta448]

The amplified sound is because the pump is running at low pressure without any restriction, meaning it will spin faster and will flow much more. Running it this way will probably shorten it's life considerably.

Your problem is very likely in the machining of the AFPR, but is definitely due to the AFPR not functioning properly. A bad AFPR can cost you a pump.