Will low fuel pressure cause no start?
Thread Starter
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Joined: Jul 2004
Posts: 84
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From: St Catharines
Car: 1987 IROC
Engine: LS1
Transmission: T-56
Axle/Gears: 3:42, 10 Bolt LT1
Will low fuel pressure cause no start?
Car sat for 15 years, TPI 305. Just put together the top end. Cranks but no start.
Checked the fuel pressure at the rail, 20 psi. I can hear the pump kick on.
I blocked the return line and and cycled the key for a few times, still 20 psi.
Left the gauge connected over night and came back and it was still at 20
I'm going to replace the fuel filter and see if that does anything.
Will low fuel pressure cause a no start? I don't get a sputter or puff or anything.
Can someone show me what wires I jumper on the fuel pump relay to make it run constant.
Thanks.
Checked the fuel pressure at the rail, 20 psi. I can hear the pump kick on.
I blocked the return line and and cycled the key for a few times, still 20 psi.
Left the gauge connected over night and came back and it was still at 20
I'm going to replace the fuel filter and see if that does anything.
Will low fuel pressure cause a no start? I don't get a sputter or puff or anything.
Can someone show me what wires I jumper on the fuel pump relay to make it run constant.
Thanks.
Supreme Member
Joined: Jul 2009
Posts: 2,328
Likes: 9
From: Kitchener, ON
Car: 1988 GTA
Engine: LB9
Transmission: T5
Axle/Gears: 3.45
Re: Will low fuel pressure cause no start?
20 PSI is way too low. Needs to be over 40 without vacuum. I would expect a sputter at 20 PSI though.
Trust you drained the 15 year gas out of it and cleaned the tank. Fuel pump is likely toast, as well as the regulator and maybe the injectors.
With the relay disconnected, applying 12v to tan/white wire on the connector will run the fuel pump.
Trust you drained the 15 year gas out of it and cleaned the tank. Fuel pump is likely toast, as well as the regulator and maybe the injectors.
With the relay disconnected, applying 12v to tan/white wire on the connector will run the fuel pump.
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Joined: Sep 2009
Posts: 1,591
Likes: 5
From: WI.
Car: 1987 iroc
Engine: 383 TPIS intake, Dyno Don headers
Transmission: 700R4 w/Pro-built Auto/transgo 2-3
Axle/Gears: 3.27/3.70 borg warner 9 bolt
Re: Will low fuel pressure cause no start?
The fuel filter is probably plugged after sitting for 15 years.
Thread Starter
Junior Member
Joined: Jul 2004
Posts: 84
Likes: 0
From: St Catharines
Car: 1987 IROC
Engine: LS1
Transmission: T-56
Axle/Gears: 3:42, 10 Bolt LT1
Re: Will low fuel pressure cause no start?
I want to make sure I am dealing with the right connector. I brought up a wiring diagram and saw the fuel pump connector had a red wire with it. This connector was plugged into the MAF power relay. This would be the right connector for the fuel pump right?
Supreme Member
iTrader: (2)
Joined: Sep 2009
Posts: 1,591
Likes: 5
From: WI.
Car: 1987 iroc
Engine: 383 TPIS intake, Dyno Don headers
Transmission: 700R4 w/Pro-built Auto/transgo 2-3
Axle/Gears: 3.27/3.70 borg warner 9 bolt
Re: Will low fuel pressure cause no start?
Here is the factory wiring diagram, https://images.search.yahoo.com/imag...arch.yahoo.com Looks to be the left relay.
Thread Starter
Junior Member
Joined: Jul 2004
Posts: 84
Likes: 0
From: St Catharines
Car: 1987 IROC
Engine: LS1
Transmission: T-56
Axle/Gears: 3:42, 10 Bolt LT1
Re: Will low fuel pressure cause no start?
I changed the fuel filter and ran the pump constant. While the return line was blocked it took about 20 seconds to build 35 psi. I'm guessing I'll need a pump change?
I also have a no spark condition. I ohmed the pickup coil to 700 ohms. While cranking with a meter attached on AC I only got a max output of .4V. According to this site it should fluctuate from 1.3 to .3. Does it sound like the pickup coil is shot?
I brought the ICM in to be tested. They tested it 10 times in a row with no problem. I'm not getting an output to the coil, based on the LED flashing test from the same site.
Thanks for all the help so far
I also have a no spark condition. I ohmed the pickup coil to 700 ohms. While cranking with a meter attached on AC I only got a max output of .4V. According to this site it should fluctuate from 1.3 to .3. Does it sound like the pickup coil is shot?
I brought the ICM in to be tested. They tested it 10 times in a row with no problem. I'm not getting an output to the coil, based on the LED flashing test from the same site.
Thanks for all the help so far
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Thread Starter
Junior Member
Joined: Jul 2004
Posts: 84
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From: St Catharines
Car: 1987 IROC
Engine: LS1
Transmission: T-56
Axle/Gears: 3:42, 10 Bolt LT1
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