[El Toro]

I have a 1997 Ford F350 XLT with a e fuel system. Out of the pump im getting 75 psi and flow is great. However, testing on the return under load it is dropping to 14psi. I have looked at the the fuel lab regulator and it is working fine. I am a little lost on where to test next. I am thinking I am over looking something.

Thanks in advance!

Aaron

 

[White95f250]

Need more details.

What regulator? What type and size fuel line?

Should be no pressure on the return line to the tank. From pump to regulator it should be nearly the same pressure as it is out of the regulator. Out of the regulator should be 60psi constant even under load.

If you are losing pressure out of the regulator then you need to test pressure pre regulator to see if is the pump not keeping up.

Will be beneficial to know how it is all plumbed.

 

[El Toro]

Need more details.

What regulator? What type and size fuel line?

Should be no pressure on the return line to the tank. From pump to regulator it should be nearly the same pressure as it is out of the regulator. Out of the regulator should be 60psi constant even under load.

If you are losing pressure out of the regulator then you need to test pressure pre regulator to see if is the pump not keeping up.

Will be beneficial to know how it is all plumbed.

• Fuelab Prodigy Regulator (no leaking out of the brass nipple)
• I believe hose is 1/2"
• Pre Regulator is coming in at 75psi with the regulator set at 63-65psi
• Then when under load it drops significantly to (14-15 psi). My understanding is it is supposed to drop just a few psi

This is the kit that was installed 3 years ago

https://444fab.com/shop/ols/products/obs-premium-kit

I am not a mechanic sorry , may have miss quoted the return.

 

[White95f250]

Where exactly are you checking the pressure? On the regulator or before it goes in to the heads?(out of the regulator)

Is the pressure dropping pre regulator?

Trying to determine if it is the regulator or the pump.

 

[El Toro]

Where exactly are you checking the pressure? On the regulator or before it goes in to the heads?(out of the regulator)

Is the pressure dropping pre regulator?

Trying to determine if it is the regulator or the pump.

Before it goes into heads
Testing right after pump (good PSI)

Regulator is good, i called fuel lab and we went through it and no issue.

 

[White95f250]

So no issue with the regulator and all is good now or still having the pressure drop?

 

[El Toro]

So no issue with the regulator and all is good now or still having the pressure drop?

Still having fuels PSI drop out of regulator.

 

[White95f250]

Doesn't quite make sense. If the fuel pump maintains pressure under load but it drops out of the regulator then it is the regulator.

If this is a new problem then the regulator is on its way out.

If the fuel pressure drops before the regulator then the pump is not keeping up.

 

[El Toro]

Doesn't quite make sense. If the fuel pump maintains pressure under load but it drops out of the regulator then it is the regulator.

If this is a new problem then the regulator is on its way out.

If the fuel pressure drops before the regulator then the pump is not keeping up.

agreed it is whacky. I am gogin to pick up antoher BOch pump in a bit and see if that soles the issue.

 

[El Toro]

UPDATE:
Replaced the pump and psi returned to normal but truck was still stalling. Come to find out pump is constantly running and does not do the normal 2-5 second prime and turn off. After much testing it seems to be that the EEC has failed and that has been the issue all along. It basically burned out the other pump staring the engine of fuel. I have sent in my PCM testing and I’m now waiting for it to arrive.

 

[Patrick Feeley]

I'm not sure how the PCM would be causing the pump failure. It does not control anything to do with the fuel pump (at least on the e-fuel setups I've seen). If it is the cause in your case, how is the PCM controlling the pump? Cheers!

 

[El Toro]

Will update when the PCM test comes back.

 

[Patrick Feeley]

Still confused: How is the PCM controlling the fuel pump? Cheers!