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Join Date: Jun 2006
Location: Virginia Beach
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72 911T MFI ele fp troubleshooting
Background:
Last winter I purchased a 72 with original engine and MFI. I've done a bit of work to get it running as the car sat for some time. Removec the electrical fuel pump and cleaned and check. Didn't flow check it. Car runs great until it gets a bit of heat saturation then leans. Question: I need to check the fuel pump output and pressure. My spec book says min flow is 900 to 1000cc oc flow in 30 seconds. Where is the best place to check this? Filter outlet? fuel supply to the filter? Return to the filter? As always any response is appreciated,
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Rusty 71 911E 55 PreA speedster 85 Turbo look Cab 62 Twin Grille Roadster (getting close) |
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03-23-2009, 06:32 AM
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Have you checked this out. I do not have the answer but I am sure it is in here some where.
Ultimate MFI resources thread Good Luck.
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Mike '99 Isuzu VX, 2005 Audi A4 1.8T Quattro '96 BMW 328ic '73 911T Targa SOLD www.flickr.com/photos/fenderbender813 |
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03-23-2009, 03:10 PM
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72 911 t
If the car has been sitting up for some time. You need to pull the tank sending unit out & have a look. Most likely rust & varnish will cover the inside of the tank. What normally happens the car will run fine untill you drive or run it a while. The rust will be drawn to the stainer screen @ the bottom of the tank & will restrict flow or if its bad fuel starve the engine. The 1st thing I do when bringing a hanger queen back to life is pull the tank & repair it. I have yet to see 1 that wasn't rusted inside. We repair them here in house. Not recomemded for DIY. Or peplace the tank with new not used.
Howard 
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Howard Freeman 80 911 SC & 74 914 1.8 79 930 & 83 SC coupe,03 996 TT,02 996 C4 03 X/5 3.0. 370,186 miles now Sons daily driver 10 X5 3.0I 224,515 miles |
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03-23-2009, 03:27 PM
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Mike, thanks for the link. there is plenty of great research done by this group. Went down to the shop this evening and got under the car. I had an aftermarket fuel pump on it. I found a couple of older pumps and between the two got and original one on and fired it up. What a difference, fuel started squirting out of the filter gasket. Pressure made a big difference.
One further problem is that I had to disconnect the cold start solenoid as fuel was squirting out of the lines when the car was running. I thought those were only injecting fuel on start up. I'll deal with that another day.
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Rusty 71 911E 55 PreA speedster 85 Turbo look Cab 62 Twin Grille Roadster (getting close) |
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03-23-2009, 03:29 PM
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Howard, will take your advice and pull it next week. PO had cleaned it but not sure if it has been treated.
thanks for the reply
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Rusty 71 911E 55 PreA speedster 85 Turbo look Cab 62 Twin Grille Roadster (getting close) |
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03-23-2009, 03:32 PM
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+1 on the tank and make sure the tank filter (brass screen) is clean mine was varnished closed. P.O. Had the tank lined at one time and is still good. This thread will help with your spare pump. MFI Open Heart Surgery II - The Fuel Pump I wish I had a spare one. (someday)
The cold start works off a thermo time switch (sending unit). Mine is disconnected due to a leaking line that I am working on right now. Some guys mount a push button switch on the dash to actavate it when they need it. Sounds like you have a good start. Best of luck.
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Mike '99 Isuzu VX, 2005 Audi A4 1.8T Quattro '96 BMW 328ic '73 911T Targa SOLD www.flickr.com/photos/fenderbender813 |
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03-23-2009, 03:56 PM
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