75 911S CIS help

[jfd]

How to run the fuel pump without starting the engine? Trying to evaluate injector condition.
Any help is appreciated.
Thanks JFD

[Jim Breazeale]

Just run leads direct from the battery to the pump.

Regards

Jim

[edmayo]

Unplug the safety switch, use a mirror and look behind the air sensor plate housing for a (green I think) two pin plug. You'll know if you got it, the pump will run as soon as you unplug it, ignition on of course.

[jfd]

The pump is on the left trailing arm, not easily accessible. Is that switch on the control pressure regulator? I heard you could "bridge" contacts 87a and 30 on the relay in the left engine compartment, but that is not working?
Thanks

[M_deJong]

Factory manual wiring diagram says the fuel pump relay and safety switch (guessing its on the fuel distributor - gets a signal from the air flapper) started with the 1976 MY. MY75 the fuel pump should run whenever the ignition is on.

Assuming you do have a relay, either bridge 87a to 30 or ground terminal 85 with the ignition on according to the 1976 wiring diagram.

What I used to do is pull all the injectors and put them in clear beer bottles. Then manually move the air plate to start them spraying. Easy to see if there is a laggard among the 6, and to see the spray pattern. Running them wide open pushes a whole lot of fuel through. A little added percussion can help clean them out.

Mike

[Jsottile]

JFD– Assuming you activated the pump, graduated baby bottles work well for volume check. Just cut the nipples to capture the fuel and avoid the mess. If you hook your gauge up at the same time you can check pressures at the same time. Also, it’s easy enough to bench check pop off pressures and find leakers if you have a hand pump. Good luck

[edmayo]

Thanks Mike, guess i jumped ahead one year,,,,,memory meltdown!

[jfd]

Thanks Guys, Great tips. What a helpful organization this is.
jfd