Fuel pressure 101 question.

Fuel pressure 101 question.

Postby Torpedoman592 [OP] » September 14th 2012, 3:30pm

Hi all. Thanks in advance for any help. Regarding fuel pressure and where it is needed when your motor is off for the next start-up / does anyone know if the fuel system in my 99 Astro is designed to keep a certain amount of pressure in the fuel line when engine is not in use. It seems logical – you have to have fuel at the ready right there at the engine when you crank it over right? I recently (2 months ago) had a new fuel pump and filter put in my 99 Astro. If I leave it sit for longer than 8-9 hours and try to start it the engine takes 45 – 60 seconds to start and when it does runs rough and bucks for just a little while until something happens then it runs strong and trouble free for as long as I need. That something I’m thinking is fuel pressure related. I’m thinking I have a slow leak somewhere in the line or at one of the connections but this only makes sense if in fact pressure is suppose to be up at the engine in the line when engine is off. If true I’m thinking a leak could explain it because when I’m trying to crank it I can imagine the pump sending fuel through an empty line until it reaches the engine, that’s why it takes so long to start but I’m not a mechanic. If when not in use I start it before 9 hours it will always fire right up – if I wait past the 9 it takes almost a minute to crank over. Can someone tell me what might be going on, a leak or a defective new fuel pump. Thank you.
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Re: Fuel pressure 101 question.

Postby chevymaher » September 14th 2012, 3:40pm

When you turn the key on it should have 60-62 lbs and hold it for a half hour. In that ball park.
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Re: Fuel pressure 101 question.

Postby Torpedoman592 [OP] » September 19th 2012, 7:22pm

Thanks. I'm wondering if anyone knows the state of the fuel pressure say at 4:00 am when your sleeping and the Astro is parked in the driveway and hasnt been used since supper time. Is there pressure in that line up near the engine?
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Re: Fuel pressure 101 question.

Postby Sailing_Faith » September 19th 2012, 7:47pm

Torpedoman592 wrote:Thanks. I'm wondering if anyone knows the state of the fuel pressure say at 4:00 am when your sleeping and the Astro is parked in the driveway and hasnt been used since supper time. Is there pressure in that line up near the engine?


Oh great! Something else to lay awake and think about at 4am.... :ugeek:

I suppose it would depend on when you last drove it.

The fuel pump spins up when you turn the key (you normally will hear it run for a second when you turn the key to 'run' before you crank the engine over....

WRT the OP... try putting a gauge on it and see what you get. Maybe your pump it taking too long to get the pressure up? Seems more likely it is low or that you have a separate problem (something like a vacuum leak could cause a hard start like you describe)
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Re: Fuel pressure 101 question.

Postby jrsride2002 » September 19th 2012, 8:06pm

Torpedoman592 wrote: Is there pressure in that line up near the engine?


Yes, if you take off your doghouse. Their will be a hard line with a port/valve you can attach a pressure sensor to. At least that is how it is on my '01 Astro.

Should look something like this:

Image

DONT press that port/valve in unless you like gas in the cab... I like the smell of gas, just not in the cab...

Im sure if you do some picture hunting in this website or google, it will show it to you.

Best of luck,
~Junior

This could help too:
https://www.astrosafari.com/viewtopic.php?f=9&t=4079
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Re: Fuel pressure 101 question.

Postby jrsride2002 » September 19th 2012, 8:41pm

I found it.... In that link i gave you... :oops: :oops:

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It will be in this general area... Well again, is on my van.

Best of luck dude! And welcome aboard! :banana:
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