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Wrench Therapy Inc.
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Fuel pump running when it's not to!
!983 Base. 99% restored but have not done a lot with the fuel system except new sending unit, new fuel filter, withchunter injector service, new fuel lines. Car ran great last week with no problems at all. Drove 110 miles. Parked her and haven't started it in 2 weeks. Went out tonight to take her for a spin around the neighborhood and I put the key in the ignition turned to ON and the fuel pump came on and ran continuously. She would crank, but not start. In about 30 seconds the engine was nearing hydro lock with fuel. I know this because I pulled the fuel pump fuse, removed the spark plugs (all out before moving on) disconnected the coil lead and placed it in safe location, placed a large shop towel over the cylinders, and turned the engine over and a good bit of gas came out of all cylinders. Normally when I get in the car and turn the key to ON you do not hear the fuel pump running and the car starts and runs fine. Now, when the key is in the ON position it is on and filling up the cylinders with gas flooding and eventually hydrolocking the motor. Could this be a bad relay keeping the fuel pump on? I knoe a bad relay can keep a pump off. Bad check valve? Faulty pump? But it is pumping quite a bit of fuel, but sounds kind of noisy. The gauge is showing about an 1/4 to an 1/8 tank. I believe that to be accurate. Any help would be appreciated because she looks so nice inside and out.
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10-13-2014, 04:38 PM
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Registered
Join Date: Jun 2014
Location: Lake County, FL
Posts: 820
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The relay failing ON would only be the result of the relay contacts welding shut, which is much less common than a coil failure. Clarks garage says (not my personal experience) that the fuel pump relay failure is caused normally by a bad solder joint internally or a failed diode. Pulling the relay and using a ohm meter to check between pins 30 and 87b would tell you if the relay is stuck on, but that relay doesnt cycle the pump on and off so it wouldnt be the issue...
Last edited by Bradical; 10-13-2014 at 05:11 PM.. |
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10-13-2014, 05:06 PM
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944 addict
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Sounds like a relay failure to me too. A replacement on ebay is about $20. Quick and easy way to eliminate or isolate the problem. Pull the DME relay to see if the pump stops.
__________________
3 944's, 2 Boxsters and one Caman S, and now one 951 turbo. Really miss the Cayman. Some people try to turn back their "odometers." Not me. I want people to know 'why' I look this way. I've traveled a long way and some of the roads weren't paved. |
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10-14-2014, 07:33 AM
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Ingrid
Porsche 944 NA
1986 Porsche 951
