Replace low pressure fuel pump? |
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Doc97
Newbie Joined: May-28-2007 Location: United States Status: Offline Points: 9 |
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Posted: May-28-2007 at 4:29pm |
I suspect I need to replace the low-pressure fuel pump on our 97 SN, GT-40 351 EFI. I'd appreciate your advice before ordering a new pump though.
We went out for the first time this year on the weekend. The engine started fine and warmed up normally as we idled out of the no wake zone. Then it stumbled and died a minute or so after I opened the throttle. Subsequently it cranked normally, fired intermittently, but wouldn't start. Here's what I know after a few hours of messing around... No fuel comes out of the line from the low-pressure pump to the FCC whether the line supplying the pump is from the tank or a short piece of fuel hose immersed in an external tank. Should the low-pressure pump be able to prime itself? The engine runs fine at idle for several minutes if I pull fuel through the low pressure side of the fuel circuit all the way back to the tank return line using DIM's Suck Up vacuum pump. Then it stumbles and dies again. One other concern is that when pulling fuel through the low-pressure side I see air bubbles mixed with fuel coming back through the tank return line. Is this normal or could my problem be an air leak in the low-pressure fuel circuit, or a leak and bad pump? I've changed the fuel filter. Last year I added Stabil to the tank and made sure it ran long enough to pull some through the fuel system before we put it in storage. It's clear there's a lot of expertise on this forum and I appreciate your advice! Thanks, Steve |
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9360SAN
Newbie Joined: August-31-2006 Location: Hong Kong Status: Offline Points: 23 |
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The low pressure can prime itself,and this is the reason for using it,if the fuel line leaks air, this will definetly cause fuel not suck up,use a peice new line for test
if the motor turning, it will suck certain amount of fuel,even the screen stuck some dirt,you can heard the pump turn when key on? |
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Go on wakeboard
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Doc97
Newbie Joined: May-28-2007 Location: United States Status: Offline Points: 9 |
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I can hear the pump run for 5 seconds or so when the ignition is turned on. I tried a 3 foot piece of new fuel line in a 5 gallon gas can. Once again, the pump ran but no fuel came out of the output line. I suspect the pump's bad.
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M3Fan
Grand Poobah Joined: October-22-2005 Location: United States Status: Offline Points: 3185 |
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The pump still makes noise if it's bad. It's a tease that way. Replace it- if it's not bad, it will go bad soon anyway. Long history of problems with that pump on the GT40.
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2000 SN GT40 w/99 Graphics/Gel
2016 SN 200 OB 5.3L DI https://forum.fifteenoff.com |
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Doc97
Newbie Joined: May-28-2007 Location: United States Status: Offline Points: 9 |
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Thanks for your advice. I replaced the pump and that solved the problem.
I saw another thread where this pump was described as almost a routine maintenance item. They advised considering changing it around 300 hours and keeping a spare on hand. |
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