EFI static fuel pressure drop

[chuzie]

Most of our EFI fuel systems prime to 40psi; mine does too. I have noticed some folks' fuel pressure remains at 40psi long after the key is off for hours or even days.

My system drops to 20psi after sitting for 5 minutes. I thought this may be an indication of a failing fuel pressure regulator so I replaced it yesterday. Unfortunately, the result was the same. It was not until I clamped my fuel line from the HP pump to the fuel rail did the pressure cease to drop.

My pressures with the engine running are fine and without issue.

Does this static pressure drop mean anything? Should I care?

 

[bmc69]

Does this static pressure drop mean anything? Should I care?

No....and no.

 

[chuzie]

Well why in the hell didn't i ask that question before i replaced the regulator?

Thx.

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[70_Steve]

Does this static pressure drop mean anything? Should I care?

My EFId 351 has cold start issues. OK, and it has warm start issues too... Takes the engine turning over several times before the engine will start. Or, let the engine turn over several times, turn the key OFF, then try to start, and it will start immediately.

My fuel pressure drops like a rock as soon as the pump stops. I don't know (never bothered to research) whether the E2000 pump I'm using has a check valve in it. If it does, it's dam sure not working! I keep threatening to install a check valve on the outlet of the pump.

I was told that at least part of the cold start issue is the fuel pressure having to build from 0 PSI when I try to start. I've learned that if I cycle the key to ON a couple times, until I hear the pump build pressure, the engine starts on about the second revolution. Much quicker than just turning the key.

 

[chuzie]

Surely someone knows what this is happening.

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[Viperwolf1]

Surely someone knows what this is happening.

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The pressure is bleeding back through your pump. If it's very slow, like it sounds it is, it isn't a problem.

 

[chuzie]

And if it were fast?


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[ScanmanSteven]

I've had lots of fuel issues, not sure about the drop as mine does that also, but, I think the E2000 is what I'm using off an '88 pu which originally had a low pressure pump in the tank which had a check valve. Mine builds pressure on the initial key on so I don't worry about it. As long as the pump builds pressure when you turn the key on I wouldn't be concerned.

 

[Viperwolf1]

And if it were fast?


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If it's bleeding internally at the pump it can become an inconvenience like Steve said but it should be fine when the pump is running. I kind of like the idea of it bleeding back into the tank. Prevents external leaks and varnish buildup inside the fuel system when it sits.

 

[jw0747]

if it's not causing a problem with either the engine running and/or starting then it shouldn't be a concern. mine does the same thing. I carry a spare regulator but no need to change it unless a fuel delivery problem to the injectors rears its ugly head.

 

[anoblefox]

ford uses a "duckbill valve" on the return line inside the gas tank. The purpose of this is to keep fuel in the lines and not let the return line siphon the fuel out of the lines. It makes for quicker starting.
Just cycle the key twice and it should start right up.

 

[chuzie]

I wonder if i can reflash the eec to prime 4 seconds instead of 2.

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