Quote:
Originally Posted by 1972BlueC20
Ok guys, some of you have been seeing my posts over the weeks and months and may know that I was having some issues with fuel pressure and some initial WOT hesitation more recently.
I adjusted the accelerator pump first and had no success with the hesitation. I had a new accelerator pump ready to install but first I wanted to try a regulator.
I installed a fuel pressure regulator today and set the PSI to 5.5 since I'm running an Edelbrock and it seems that the hesitation is now gone. I only drove it once for about 15 minutes and did several cruise to WOT and dead stop accelerations and it never hesitated. It actually felt like it had more power and was running much better having the pressure regulated.
Is that possible? Less fuel pressure would = more power and performance? Excuse that dumb question, but I'm learning.
The only problem that I now have left which I was hoping would be fixed with the addition of the regulator but wasn't, is the issue that after the truck sits after running and the pressure needle drops back down to 0 after the fuel runs back down the line.....it's hard to start.....you have to stand on the ignition for about 5 seconds before the fuel makes its way back up to the carb.
If you turn the truck off even if the engine is scolding hot, and the pressure is still showing on the gauge to be anymore than 0...whether its immediately after you turn the truck off or even 10 minutes after, then it fires right up immediately.
Once the pressure in the line drops to 0 PSI = hard start.
Is that normal to have hard start after sitting? How can I fix it?
Whats interesting is it starts right up every morning when its cold. Even though the pressure is at 0 in the morning.....I do however give it a squirt before cranking but it always fires right up.....giving it a squirt when hot after the pressure drops to 0 doesn't work during the day like it works in the morning. Its driving me crazy.
Also is it normal that when I rev the engine with my hand while watching the fuel pressure gauge that the pressure dips down a little on throttle?
Sorry I know that was long and is a lot of questions!
I appreciate your time and patience with me!!
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It will be interesting to see if the hesitation is really gone. The only way the fuel pump pressure regulator could have had an impact is if the pressure was blowing the inlet needle off the seat (over-powering the float) and spilling fuel out the top of the carb through the vent tube/s causing an over-rich mixture. You should have been able to see black smoke if that was happening.
I forgot why you didn't use the carb that came with the engine. Is that an option?
Whether the engine is hot or cold, it obviously has fuel in the bowl more than adequate to start the engine (the engine was hot when you shut it off, then started when cold so fuel didn't dis-appear then mysteriously appear in the bowl cold). How do you know fuel is running back down the fuel line?
After sitting over night, remove the air cleaner and see if the accelerator pump will put out more than one squirt. If it is able to put out 2-3 full squirts, I would say the fuel bowls are full enough.
The fact that it still starts hot only before the pressure goes to zero then doesn't start, but somehow fires right up cold (cold requires more fuel) makes no sense to me at all. Enough fuel in the bowl to start it hot if enough in the bowl to start it cold. Yet, you relate this to the 0 fuel pressure. You got me stumped hope somebody can make sense of this for you.
If it were inadequate spark (poor power supply to the coil), it would not start well hot at all and having more than 0 fuel pressure would not make a difference.
Something is missing in this picture.