Normal Fuel Pressure Readings
Thread Starter
Intermediate
Joined: Jun 1999
Posts: 43
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From: Mesa AZ
Normal Fuel Pressure Readings
Hi All,
Need some help troubleshooting a hard start problem. My 93 has an intermittent starting problem--some times it starts right up and other times I have to press the accelerator a little to get it started. This problem occurs anytime, hot or cold. I just checked the fuel pressure reading a few minutes ago and was wondering if it is normal. The pressure cold, before turning key, was 0 psi and after turning the key on without starting, the pressure moved up to 39 psi. The reading running at idle is 39psi with vacuum connected to the fuel pressure regulator and 48psi disconnected. After turning the engine off the pressure was about 39psi and I only watched it for a few minutes before disconnecting and it held at 39 psi. Are these normal readings or do these readings indicate a problem? If these are normal what should be my next step in troubleshooting the problem. Thanks in advance for the help
Need some help troubleshooting a hard start problem. My 93 has an intermittent starting problem--some times it starts right up and other times I have to press the accelerator a little to get it started. This problem occurs anytime, hot or cold. I just checked the fuel pressure reading a few minutes ago and was wondering if it is normal. The pressure cold, before turning key, was 0 psi and after turning the key on without starting, the pressure moved up to 39 psi. The reading running at idle is 39psi with vacuum connected to the fuel pressure regulator and 48psi disconnected. After turning the engine off the pressure was about 39psi and I only watched it for a few minutes before disconnecting and it held at 39 psi. Are these normal readings or do these readings indicate a problem? If these are normal what should be my next step in troubleshooting the problem. Thanks in advance for the help
Intermediate
Joined: Nov 2005
Posts: 39
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Fuel pressure is apparently OK, but if you ever need it, there is a great article in the archives about fuel pressure--someone did considerable research and came up with real world numbers.
Click "other" at the top of the forum page, then "tech tips," then "C-4." In search block type in "fuel pressure," and look for the title "Fuel Presure Holding Numbers." Everything you wanted to know and then some.
Click "other" at the top of the forum page, then "tech tips," then "C-4." In search block type in "fuel pressure," and look for the title "Fuel Presure Holding Numbers." Everything you wanted to know and then some.
Le Mans Master
Joined: Dec 2004
Posts: 5,789
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From: Myrtle Beach SC
St. Jude Donor '05-'06
Le Mans Master
Joined: Feb 2005
Posts: 5,146
Likes: 3
From: The Motor City
With reference to PSI.
Mine was similar w/out vac 48psi, w/vac 36psi. I wanted to change the strainer in tank so when I pulled it, the element was deteriorated replaced that and pump (GM stock), because pump was probably sucking in who knows what. That gave me 3 more psi at the rail and after adjusting it back to 48 w/out vac. when I put vac. back on it now only drops to 46psi.
I am not saying yours is a problem, only giving my results. Mine did not have hard starts so the pressure had no effect on my starting. I would inspect the TB, clean if nessessary.
Mine was similar w/out vac 48psi, w/vac 36psi. I wanted to change the strainer in tank so when I pulled it, the element was deteriorated replaced that and pump (GM stock), because pump was probably sucking in who knows what. That gave me 3 more psi at the rail and after adjusting it back to 48 w/out vac. when I put vac. back on it now only drops to 46psi.
I am not saying yours is a problem, only giving my results. Mine did not have hard starts so the pressure had no effect on my starting. I would inspect the TB, clean if nessessary.
Last edited by mseven; Jan 16, 2006 at 06:31 AM.
