fuel pump doesnt turn off!

91 S10 · 10-10-2009, 10:08 PM

I have a 91 s10 (used to be a 2.5) with a stock in tank pump run to a mallory regulator and a bypass to tank for a carbed motor. well I havent ran my truck yet but i just finished plumbing my fuel lines and wanted to check for leaks, which i didnt have. But i noticed that when i turn the key to where it would purge before now the pump just continues to run? I am using the factory relay. Can i rewire it so it purges and then shuts off when the line has built pressure? Was the purge controlled by the computer? Is it bad to have the pump run like that, before the truck fires up?

Maverick2664 · 10-10-2009, 10:57 PM

i dont know a whole lot about aftermarket fuel pumps, but we had a mustang with some mods done to it come in to my shop last year and it had an aeromotive pump on it, and it did the same thing youre describing, turn on the key and it would just run and run... noisy thing too

but your guess is as good as mine, i dont know if thats how theyre supposed to work or not

***AVTekk*** · 10-10-2009, 11:50 PM

The purge is controlled by the computer, there is absolutely nothing that reads line pressure then shuts it off once its reached that set limit, the ecm simply was programmed with a few seconds of purge to get the line ready, where it built enough pressure or not.

Since you have what sounds like a reasonable working set up, you will be fine with the pump running all the time, but you may want to run a kill switch ont he dash so you can shut it off for any particular reason.

91 S10 · 10-10-2009, 11:58 PM

Quote: Originally Posted by AVTekk

The purge is controlled by the computer, there is absolutely nothing that reads line pressure then shuts it off once its reached that set limit, the ecm simply was programmed with a few seconds of purge to get the line ready, where it built enough pressure or not.

Since you have what sounds like a reasonable working set up, you will be fine with the pump running all the time, but you may want to run a kill switch ont he dash so you can shut it off for any particular reason.

So this is normal for a factory pump when running a carbed motor? Is the pump running consistant like that going to cause it to burn out prematurely?
Is there any other options then running a switch on the dash?

purevil115 · 10-11-2009, 12:46 AM

thats how my holley pump is. turn key forward and it runs and turn key off it turns off, will not burn it up and just put a swtich inline so if need be you can shut it off.

towb3 · 10-11-2009, 12:00 PM

I had to run a switch to mine as well. Just in case you are doing something that requires ignition on and not wanting to run the pump.

10-10-2009, 10:08 PM	#1
91 S10 Registered User Join Date: Nov 2003 Posts: 385 Location: Langley B.C User is: OffLine	fuel pump doesnt turn off! I have a 91 s10 (used to be a 2.5) with a stock in tank pump run to a mallory regulator and a bypass to tank for a carbed motor. well I havent ran my truck yet but i just finished plumbing my fuel lines and wanted to check for leaks, which i didnt have. But i noticed that when i turn the key to where it would purge before now the pump just continues to run? I am using the factory relay. Can i rewire it so it purges and then shuts off when the line has built pressure? Was the purge controlled by the computer? Is it bad to have the pump run like that, before the truck fires up?
	[Reply w/Quote]

10-10-2009, 10:57 PM	#2
Maverick2664 Heavy Metal Body Man Age: 25 Join Date: Jun 2007 Posts: 2,843 Location: Erie PA User is: OffLine	Re: fuel pump doesnt turn off! i dont know a whole lot about aftermarket fuel pumps, but we had a mustang with some mods done to it come in to my shop last year and it had an aeromotive pump on it, and it did the same thing youre describing, turn on the key and it would just run and run... noisy thing too but your guess is as good as mine, i dont know if thats how theyre supposed to work or not
	[Reply w/Quote]

10-10-2009, 11:58 PM	#4
91 S10 Registered User Join Date: Nov 2003 Posts: 385 Location: Langley B.C User is: OffLine	Re: fuel pump doesnt turn off! Quote: Originally Posted by AVTekk The purge is controlled by the computer, there is absolutely nothing that reads line pressure then shuts it off once its reached that set limit, the ecm simply was programmed with a few seconds of purge to get the line ready, where it built enough pressure or not. Since you have what sounds like a reasonable working set up, you will be fine with the pump running all the time, but you may want to run a kill switch ont he dash so you can shut it off for any particular reason. So this is normal for a factory pump when running a carbed motor? Is the pump running consistant like that going to cause it to burn out prematurely? Is there any other options then running a switch on the dash?
	[Reply w/Quote]

10-11-2009, 12:46 AM	#5
purevil115 Registered User Age: 22 Join Date: Feb 2006 Posts: 2,466 Location: lousiville, Ohio User is: OffLine	Re: fuel pump doesnt turn off! thats how my holley pump is. turn key forward and it runs and turn key off it turns off, will not burn it up and just put a swtich inline so if need be you can shut it off.
	[Reply w/Quote]

10-11-2009, 12:00 PM	#6
towb3 Ehhh! Age: 27 Join Date: Jun 2008 Posts: 1,394 Location: Belleville, IL/St.Louis User is: OffLine	Re: fuel pump doesnt turn off! I had to run a switch to mine as well. Just in case you are doing something that requires ignition on and not wanting to run the pump.
	[Reply w/Quote]