Fuel Pressure drop??
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Pro
Joined: Dec 2000
Posts: 534
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From: Farmington NY
Fuel Pressure drop??
My 85 runs okay under easy driving conditions but when I put my foot down hard it will hesitate a little (sometimes) and with a fuel pressure gauge on, the pressure will drop! It doesn't impact on the idle just under load. I've also noticed when I step on it going around a corner to the left, the same thing happens, hesitation! I thought this might be the fuel pump and my mechanic said the pump wouldn't go gradually. He thought it might be the AFPR or a vacuum lead leading to the fuel pressure regulator?? I don't want to replace the fuel pump if that's not the problem. Any suggestions?? Oh, I have a Holley AFPR with is only two years old so I doubt that it leaking. Thanks. :confused:
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From: SE NY
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Re: Fuel Pressure drop?? (Gregory VanLare)
Check fuel pressure at idle with the vacuum line connected and with it plugged to assure it's behaving properly with no vacuum leaks.
If not done recently, change the fuel filter.
Before replacing the fuel pump, pull it and clean the three electrical contacts just under the mounting flange. These copper contacts become oxidized over time and can cause fuel delibery problems.
If not done recently, change the fuel filter.
Before replacing the fuel pump, pull it and clean the three electrical contacts just under the mounting flange. These copper contacts become oxidized over time and can cause fuel delibery problems.
Thread Starter
Pro
Joined: Dec 2000
Posts: 534
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From: Farmington NY
Re: Fuel Pressure drop?? (Gregory VanLare)
I just changed my fuel filter and my 85 is a TPI. I'll check the connections although I doubt they are oxidized, I had a leak and the garage said that the gaskets were crinkled and caused the leak when the pump pressurized.
[Modified by Gregory VanLare, 11:01 PM 9/9/2003]
[Modified by Gregory VanLare, 11:01 PM 9/9/2003]
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From: Saratoga Springs NY
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Re: Fuel Pressure drop?? (Gregory VanLare)
You can just unplug the vac line to the regulator and make sure to plug off the vac line as well..This will bring the pressure up a few (2-3)pounds,which should be benifical to you..
I work on nothing but FI systems, believe me, pumps DO go gradualy(spelling?)...They are usually very noisy when they are on there way out..Listen for a high pitched whine..
But if you pressure drops off like that , then yeah, id be looking at the pump if the regulator unplugged dosent help.
What does the pressure drop to, and at what rpm does it happen???How long does it hesitae and how bad??? Backfires or popping?? Give me as much as you can on just how bad it stumbles..
But it does sound like the fuel pump..
Brian
I work on nothing but FI systems, believe me, pumps DO go gradualy(spelling?)...They are usually very noisy when they are on there way out..Listen for a high pitched whine..
But if you pressure drops off like that , then yeah, id be looking at the pump if the regulator unplugged dosent help.
What does the pressure drop to, and at what rpm does it happen???How long does it hesitae and how bad??? Backfires or popping?? Give me as much as you can on just how bad it stumbles..
But it does sound like the fuel pump..
Brian
