lift pump questions
03-29-2007, 04:58 PM
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lift pump questions
Ok so installed a fuel gauge to check my lift pump, and normally it runs at about 15psi. work it hard up a hill or something and it drops maybe to 10, all that seems ok from what i have read BUT once in a while it drops down to 5psi, driving down the highway or idle doesnt matter but if i turn the key off even if for a split second and back on the pressure jumps back up to 15.
seems like an electrical problem? any ideas?
seems like an electrical problem? any ideas?
03-29-2007, 08:25 PM
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It sounds to me like your fuel filter might need changing, or bite the bullet and get an Airdog or something similar which has the fuel pump/filter/water separator together, at a more accessible place.
03-30-2007, 09:27 AM
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the fuel filter is brand new, is there something electrical that drives the pump thats maybe not always sending enough voltage to it or something? its just strange that as soon as i turn the key off and on it goes back to normal, or is there something electrical in the pumps that fail?
03-30-2007, 09:39 AM
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Your pump is on its way out. That is what my truck did and to compound it the first lift pump I picked up from napa did the same thing out of the box. Cold temperatures seem to add to the problem. I installed a second lift pump, this one a campaign pump from cummins, and it lasted about 10k or so. Each time I tried changing the filter before I changed the pump and the filters were not the problem. I finally went to a Walbro system and have had great results.
03-30-2007, 09:47 AM
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Ok guys you talked me into it ill change it! ill do a search on here to see what brands you all like and see if i can find one here someplace if not ill try the napa one i already picked up. Thanks alot all.
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03-30-2007, 09:57 AM
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Before you spend the money on a new pump. Try installing the Vulcan Draw Straw Kit. In my opinion, it sounds like the pump is intermittently drawing air bubbles at the OEM draw tube at the tank. The draw straw kit addresses this issue.
03-30-2007, 10:02 AM
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Im not sure how that would account for a 10 psi drop in fuel pressure...JMO
03-30-2007, 10:04 AM
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again with turning the key off and back on thing doesnt seem to me like it would be air in the lines would it? seems electrical to me?
03-30-2007, 10:10 AM
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What does your pressure guage say when you have the truck at WOT (Wide Open Throttle)??...that is THE best indication of the lift pumps condition.
You should be seeing no less that 7 psi at WOT.
You should be seeing no less that 7 psi at WOT.
03-30-2007, 10:24 AM
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Dr. Evil are you now sudgesting maybe its not the pump? iv got my coveralls on ready to change it but i hate to put a $300 part on my truck and find it makes no difference...
03-30-2007, 10:47 AM
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What most guys look at is the reading at cruise and WOT. The pressure at WOT really shows how well your LP will lube and cool your VP-44. Maybe check it at cruise and WOT and see how its doing before you change it.
$300 - where do you live? If you plan on keeping this truck - its time to look into upgrading the fuel system. Vulcan Big Line kits are $115 and a Holly Black is around $100. Walbro fuel systems are $300, and FASS pumps are $400-600. All USD. Lots of options and they ALL are better than the stock carter pump bolted to the side of the block.
$300 - where do you live? If you plan on keeping this truck - its time to look into upgrading the fuel system. Vulcan Big Line kits are $115 and a Holly Black is around $100. Walbro fuel systems are $300, and FASS pumps are $400-600. All USD. Lots of options and they ALL are better than the stock carter pump bolted to the side of the block.
03-30-2007, 10:57 AM
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thats $300 cad and it was actually $290 cad or something anyways this is what im saying about the pressures, at cruise it runs somewhere around 13psi and just under 10 at wot, but then it intermediatly will drop down to 5psi and stay there for any givin amount of time, but if i turn the key off and back on it jumps back up to 13 if im cruising or 15 if im idling, even if i turn it off and on so fast the truck keeps running. So its not like the pump is weak cause it can and usually does run good pressure. 
so im still confused!
so im still confused!