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mycars12

No Fuel Pressure when cranking

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I have a ep82 4efte motor and I have recently been having a problem with the car not wanting to start easily when warm.

Basically it starts fine when the car has sat for 4 or more hours but less than that and the car will crank for about 6-8 seconds and it will slowly turn on but then it will have a low idle around 600 rpm for a little before it goes up to 950-1000 (where my idle is set) also reads lean at 16.5-17 when idling low in the 600's then goes to 14.4-14.8 when 950-1000 rpm.

I have a (kinda new 6 months old) aeromotive fpr and it reads 0 when the key is in the ignition position and as soon as the car shuts off the pressure goes to 0 as well. 

I also do have a brand new fuel pump and it did not make a difference.

Battery is new as well 2 months old.

Any suggestions? 

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What ECU and injectors etc is the car running?

Aeromotive FPR's don't have a check valve from memory so don't hold pressure when the engine is switched off like others do for 30 mins or so

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It is a stock ep82 4efte so stock injectors and stock ecu. I believe the stock injectors are 295 and the ecu is a 2 plug. 

Any solutions to try and hold pressure? The problem is only mostly when it is hot though. If the regulator didnt hold pressure at all how come it would start fine when warm and hard when warm? Wouldnt it start hard all the time?

Edited by mycars12

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The only other thing it’s worth checking is your coolant temp sensor. The ecu will use this to calculate fuel delivery for cold and hot starts etc. Cheap part to change. 
 

As long as your fpr holds atleast 2.3 bar when the pump primes and the engine is cranking it won’t be that causing problems.

Do coolant temp sensor next and see if that helps. 

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Alright. I will try to find one locally and try it out to see if its fixes the problem and will report back. 

When i turn the key to the ignition position the pressure reads 0 on the fuel pressure regulators gauge. Gauge really only moves when the car is on. 

Thanks!

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With a stock ecu the fuel pump only runs when the engine is rotating ie cranking or running.  It doesn't run with just the ignition on.

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Well. The problem was fixed. Seems like my aeromotive fuel pump was not holding pressure when shut off. I checked it after @RobSR told me about that. 

Swapped the original fpr on and the car is actually running very smooth now. Thanks for the help!

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