fuel pump relay

Hoffmanmotors · 07-19-2006, 06:48 PM

so here we go, im a new porsche owner who just bought a 79 911sc. I took out the CIS fuel injection system out (wish i didnt) to replace the oil thermostat o ring and breather gasket to eliminate an oil leak, and when i put it all back together the fuel pump relay gets really hot and burns out.

Does any of this sound familliar to anyone? what did i hook up wrong or do wrong, and where should i look first. Now i just realized how much i hate the CIS injection system!! lol

Please dont dump on the thread, im just a newb who needs help...

HELP!!

TIA

Jim Sims · 07-19-2006, 07:31 PM

Exactly what did you disconnect? In a '79 the fuel pump is up front away from the engine. Did you disconnect any wiring on the top of the engine? Did you disconnect the fuel line between the fuel filter (driver's side of the engine compartment) and the engine? I'm conjecturing you may have somehow reversed it and the fuel return line back to the tank although I'm not sure that is even possible. A roll of masking tape and a permanent marking pen would have saved you a lot of grief. By the way, if properly maintained a CIS fuel injection system is very dependable.

Hoffmanmotors · 07-19-2006, 08:32 PM

Quote:

Originally posted by Jim Sims
Exactly what did you disconnect? In a '79 the fuel pump is up front away from the engine. Did you disconnect any wiring on the top of the engine? Did you disconnect the fuel line between the fuel filter (driver's side of the engine compartment) and the engine? I'm conjecturing you may have somehow reversed it and the fuel return line back to the tank although I'm not sure that is even possible. A roll of masking tape and a permanent marking pen would have saved you a lot of grief. By the way, if properly maintained a CIS fuel injection system is very dependable.

yes true the tape would have helped, and yes the CIS is very dependable. Im not sure what the hell i did! the car runs but just keeps burning up relays.

When i bought the car it needed attention to the engine, it leaked oil and has a tiny "slapping" or "knocking" sound coming from the left side a low RPM (probably cam tensioner or valve gaping). I love Porsches to death but they are so new to me and very intimidating. Not sure what i got in to! But im gunna hang in there, I got lots to learn i guess.

Jim Sims · 07-19-2006, 08:39 PM

Again, what did you disconnect? Fuel lines to/from the engine, electrical plugs from CIS devices (cold start valve, warm up regulator, air flow switch, etc.), 14 pin connector on driver's side of engine compartment?

Hoffmanmotors · 07-20-2006, 03:54 PM

Quote:

Originally posted by Jim Sims
Again, what did you disconnect? Fuel lines to/from the engine, electrical plugs from CIS devices (cold start valve, warm up regulator, air flow switch, etc.), 14 pin connector on driver's side of engine compartment?

All i disconected was the fuel line and a couple plugs, one to the cold start and so on, two black and one green plugs if i remember correctly. I also took the alternator and fan shroud off to make room to get the CIS out. i hooked them all back on just how they were. i didnt touch the 14 pin conector at all.

i'll double check everthing tonight. but im pretty damn possitive i hooked it all back together like it was. I'm sure its something small and stupid.

randywebb · 07-20-2006, 04:03 PM

what color wires did you either disconnect ...

OR ... bump against and dislodge while working there?

Early_S_Man · 07-20-2006, 04:23 PM

Hoffman,

I don't see how removing CIS components in the engine compartment could possibly affect the the fuel pump or fuel pump relay ... maybe it was a coincidence, or as Jim said -- maybe the fuel hoses are mixed up.

I suggest a test of fuel pump output into a clear container and current drain measurement at the fuel pump relay socket. The fuel pump should produce 750 cc of output in 30 seconds, and should not draw more than 8.5 Amps.