Consensus in the necessity of the in-tank pump? - update: It's out! Yuk!
09-11-2007, 01:06 AM
#31
Yesterday I went to go for a drive and the car would not start. Looked at the FP gauge on the fuel rail... "O" 
I pulled the FP relay and jumpered it. I could hear the pump being energized, but not spinning. So I disconnected everything and hooked up a battery directly to the pump and tried working it back and forth by reversing the polarity. Nothing!
I've got an 044 pump on the way, but in researching I saw that the in-tank pump is notorious for failure. I have a suspicion that some debris is causing the external pump to be seized. Since I live in Michigan - a not too hot (yet) climate, I was wondering if there was consensus or wisdom about removing the in-tank pump?
I know the 044 pump is plenty strong, just concerned about the in-tank's priming function.
I pulled the FP relay and jumpered it. I could hear the pump being energized, but not spinning. So I disconnected everything and hooked up a battery directly to the pump and tried working it back and forth by reversing the polarity. Nothing!
I've got an 044 pump on the way, but in researching I saw that the in-tank pump is notorious for failure. I have a suspicion that some debris is causing the external pump to be seized. Since I live in Michigan - a not too hot (yet) climate, I was wondering if there was consensus or wisdom about removing the in-tank pump?
I know the 044 pump is plenty strong, just concerned about the in-tank's priming function.
I purchased the car at 102k. The fuel pump 'buzzing' was prominent and annoying, especially at idle when it was most noticeable. The internal pump was toast so I replaced both - new internal, used Bosch external. I also replaced the short hose and fuel filter.
Could a dead internal pump have put strain on the external causing early failure? Maybe. Was the fuel filter clogged sufficiently to add to the strain? Possible.
My only logic is that Porsche designed the fuel system in my car to work with 2 fuel pumps. Probably overkill. They also designed it to work with 2 distributor caps & rotors. More overkill.
I just figured that for $160 I'd buy the in-tank pump. I removed the fuel level sending unit so I could see right down inside the tank. Then used small tubing to siphon out the last drop of gas around that pump. The big plastic nut screwed out easily (with a 12" crescent wrench) & the pump came out with no commotion.
I'd do it again - just my $.02.
Hawk
09-11-2007, 01:53 AM
#34
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100% normal or my pump has been dying since I installed it three years ago.
09-11-2007, 02:00 AM
#35
Under the Lift
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A split hose (very common) shouldn't cause a no-start. Most owners dom't even know that probably 80% of the 928s with in-tank pumps have a split hose.
09-11-2007, 08:58 AM
#36
Supercharged
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I think my issue was that having the split hose allowed some debris to get into the external pump and bind the impeller. I think I'm going to try and repair the in-tank pump per Loius Ott. https://rennlist.com/forums/928-forum/259184-in-tank-fuel-pump.html
I can't make it worse.
09-11-2007, 09:13 AM
#38
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My GT racecar was doing that at Road America with less than a quarter tank of fuel;
Now I can get down to 2 gallons before an issue
09-11-2007, 09:54 AM
#39
Drifting
Thanks for the input!
09-11-2007, 02:25 PM
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Andrew, That look just like the internal pump I took out of my car a couple of years ago.
SwayBar, My car was sputtering on turns when low of fuel after I had the fuel cell
installed. Marc installed a small (~2 qt) sump next to the fuel cell in front of the external
fuel pump. That took care of the problem so far.
SwayBar, My car was sputtering on turns when low of fuel after I had the fuel cell
installed. Marc installed a small (~2 qt) sump next to the fuel cell in front of the external
fuel pump. That took care of the problem so far.
09-11-2007, 02:39 PM
#41
Drifting
Thanks George.
09-11-2007, 03:56 PM
#42
Andrew, That look just like the internal pump I took out of my car a couple of years ago.
SwayBar, My car was sputtering on turns when low of fuel after I had the fuel cell
installed. Marc installed a small (~2 qt) sump next to the fuel cell in front of the external
fuel pump. That took care of the problem so far.
SwayBar, My car was sputtering on turns when low of fuel after I had the fuel cell
installed. Marc installed a small (~2 qt) sump next to the fuel cell in front of the external
fuel pump. That took care of the problem so far.
09-11-2007, 04:10 PM
#43
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Just to stay on topic. My fuel cell has an internal pump and surge box.
atlinc.com/US/download.php?file=pdfs/Bulletins/DS525_BlackBoxKit.pdf
atlinc.com/US/download.php?file=pdfs/Bulletins/DS525_BlackBoxKit.pdf
09-12-2007, 10:47 AM
#44
Supercharged
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OK, so on my way home yesterday, I tried to pick up some 1/2" fuel injector hose to attempt a repair on the internal pump. None, nada, zip... unless I want to buy 50' of it. And all I need is about what... 1" maybe 2". I'll try another place later today.
Does anyone know whay they made this thing with a section of hose on it in the 1st place? Why not just make it one solid piece?
Does anyone know whay they made this thing with a section of hose on it in the 1st place? Why not just make it one solid piece?
09-12-2007, 10:59 AM
#45
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