Gas leaking from crossover pipe

[timchar]

I recently purchased a 75 911S widebody with a 3.0 ROW motor from my neighbor. Has not been operated in 7 years. I changed all fluids, drained gas, new fuel filter and did a few other things. I fired it up and it started on third try, smoking like crazy ran for about 3 minutes then quit, it will turn over but no start. I then noticed a pretty major fuel leak coming from the crossover pipe out of the heat exchanger. Where should I look first?? Thank you. Tim

[Tidybuoy]

My guess it that one of the fuel lines that goes to the fuel distributor is leaking. This is not a good leak because it sounds like it is leaking directly onto the exhaust system.

There are two fuel lines that run behind the engine along the fire wall. One goes to the fuel distributor and the other comes from the fuel distributor (the second is the return line to the tank and also has a "T" with another line coming from the warm up regulator (WUR).

By the way, if one of these fuel lines is leaking, it's highly likely that the remaining fuel lines are old and going bad. The lines are fairly expensive but you can purchase Coline (exact replacement line) and press fit your original connectors for a lot less. There is also a guy on this board "BoxterGT" that makes these lines for a lot less than factory replacement lines. If you search fuel lines, someone on this board has posted how to make a simple jig for pressing in your fuel fittings. Coline is very hard and requires a simple jig for pressing in your fittings.

[timchar]

Thanks Vern, wouldn't I see fuel in the rear engine bay area? Tim

[Tidybuoy]

I think that depends on where exactly the leak is and how your fuel lines are routed. They can be sitting right on the rubber seal at the edge of the engine bay. It's also possible that a fuel line from the tunnel to the engine bay is leaking. I can't imagine the fuel coming from the crossover pipe but rather it's probably dripping onto it.

If you can run the fuel pump with the engine off, that would be the best way to check (with the engine off and cool).

Also, I'm not sure on the '75 but on my '74, the fuel pump is right over the rear suspension (at the torsion bar). a leak there could be spraying onto the exhaust.

[juanbenae]

excuse my ignorance.. is it coming from up above, or actually from the exhaust components? might not hurt to drop the motor to get a good look. you can also replace rubber fuel & vacuum lines. the fuel lines thru the tunnel that vern notes are much easier to pull back in with the motor & tranny sitting next to the car on dolly.....

where in nor cal?

[timchar]

Stockton, just getting the car on jack stands now and rigging up some lighting to take a better look. It looks like its coming directly out of crossover pipe but I know its got to be leaking down onto it. Going to check a few things now and will check back in soon. Thanks for your help. Tim

[timchar]

I absolutely cannot see it leaking from above down onto the crossover pipe, it's also leaking at the left heat exchanger where it connects to the catalytic converter. The heat exchangers have quite a bit of oil on them as well. Is it possible somehow there is gas in the heat exchanger crossover pipe and connection to catalytic converter from internally? Not sure my next step? Thanks Tim

[ossiblue]

Originally Posted by timchar

I absolutely cannot see it leaking from above down onto the crossover pipe, it's also leaking at the left heat exchanger where it connects to the catalytic converter. The heat exchangers have quite a bit of oil on them as well. Is it possible somehow there is gas in the heat exchanger crossover pipe and connection to catalytic converter from internally? Not sure my next step? Thanks Tim

Given that the fuel is coming from inside the cross over pipe and the car does not start, I'd suspect leaking/faulty injectors or ignition fault, initially. Once the car refused to fire, continued cranking will shoot raw fuel into the cylinders. What you are seeing may be the result of continued fuel flow from your starting efforts. Pull the dipstick and see if there is a fuel smell in the oil. If raw fuel is the problem, you risk hydro-locking your cylinders which is something to avoid. Remember, all injectors spray at the same time. The engine dying and refusal to start may be due to some other cause, but your condition now indicates a fuel flooded situation.

I'd suggest pulling a plug and check to see if it's wet with fuel. Then, loosen all plugs and turn the engine by hand to clear out any fuel. Run an injector test (someone will link you to a thread) to check if they leak and check their spray pattern and flow volume. Dry, clean/replace the plugs. Once you have the injectors satisfactorily tested and checked, try starting again.

Oh yeah, check for spark.

[timchar]

Ossi, I will start investigating the injectors. The other thing that is strange is that the fuel pump makes a very loud noise, 5 times as loud as my 3.2 made, almost like its on steroids. I think I read here abut measuring output from fuel pump? If memory serves me correctly it may have been you that commented on it? I will continue looking further into the situation tomorrow night and sunday. Thanks again for the help, Tim

[fastfredracing]

The fuel distributor may have stuck , and filled the motor with gasoline. . Id pull the air cleaner, and see if you can feel resistance against the air flow sensor plate arm with the fuel pump relay jumpered, or while someone cranks it. If it is working properly, as you lift the arm, you should feel slight resistance, and you should hear the injectors start to squeal as they are injecting fuel. If you hear squealing as soon as you jumper the relay, it is indeed stuck wide open. If the engine does not want to crank, , stop, you are hydrolocked, and need to pull the plugs . and get all that fuel out of there before you bend something
Keep us posted

[ossiblue]

Originally Posted by fastfredracing

The fuel distributor may have stuck , and filled the motor with gasoline. . Id pull the air cleaner, and see if you can feel resistance against the air flow sensor plate arm with the fuel pump relay jumpered, or while someone cranks it. If it is working properly, as you lift the arm, you should feel slight resistance, and you should hear the injectors start to squeal as they are injecting fuel. If you hear squealing as soon as you jumper the relay, it is indeed stuck wide open. If the engine does not want to crank, , stop, you are hydrolocked, and need to pull the plugs . and get all that fuel out of there before you bend something
Keep us posted

Indeed, this is another possibility^^

One other thing, you have a 75 model year car. Unless it was changed when the 3.0 was installed, you do not have a fuel pump relay, meaning, your pump will start running as soon as the ignition is turned on. If that's the case and the fuel distributor is stuck, hydro-lock is a very real danger.

Let us know what you find. If your cylinders were flooded with fuel, you will need to replace the oil before running the engine for any length of time.

[timchar]

Finally got some time to investigate further: I do have spark. The air flow sensor plate arm does have pressure to it. As soon as key is turned I hear injectors squealing very loud. There is no relay for fuel pump. So are things pointing to fuel distributor being stuck? Not sure of my next step? Should I take distributor off? Is it possible my fuel pump is pumping too much fuel? Thanks for any help, Tim

[ossiblue]

Originally Posted by timchar

Finally got some time to investigate further: I do have spark. The air flow sensor plate arm does have pressure to it. As soon as key is turned I hear injectors squealing very loud. There is no relay for fuel pump. So are things pointing to fuel distributor being stuck? Not sure of my next step? Should I take distributor off? Is it possible my fuel pump is pumping too much fuel? Thanks for any help, Tim

Injectors shouldn't squeal until the plunger in the intake is raised. Could be the plunger arm is not resting on its "stop", allowing the injectors to squirt. This can be due to the plunger arm sticking or an adjustment to the stop screw. Either of these, or the piston inside the distributor that the plunger arm pushes on will cause the injectors to squirt fuel. Now that you know the situation, do not run the pump until you solve the issue of the injectors squirting. Run the pump only to test, and only for 1 or 2 seconds.

[timchar]

I cant see or figure out anything outside the fuel distributor that can be causing this so I guess I may have to take it out and rebuild or have rebuilt. May do compression test first and consider dropping the engine because there are a number of oil leaks as well. Tim

[Tidybuoy]

Originally Posted by timchar

Finally got some time to investigate further: I do have spark. The air flow sensor plate arm does have pressure to it. As soon as key is turned I hear injectors squealing very loud. There is no relay for fuel pump. So are things pointing to fuel distributor being stuck? Not sure of my next step? Should I take distributor off? Is it possible my fuel pump is pumping too much fuel? Thanks for any help, Tim

It is unlikely that your fuel pump is the problem (even though you said it is really loud). Even if the fuel pump was putting out too much pressure, the fuel distributor has a pressure regulator in it and any pressure over approx. 70 psi is diverted back to the fuel tank.

The fact that your injectors are squealing with the key turned on, but not running, means that the central plunger (which is controlled by air flow plate) is not in its resting position. When the plunger is at it's resting point, it should be cutting off fuel to the injectors.
One thing you could try is to have someone turn on the key for a few seconds while you pull down on the air sensor arm (just under the air sensor plate). If the injector squealing stops, it means that the plunger moves but the sensor plate is out of adjustment and not fully in it's rest position.

[timchar]

Vern, key on I pulled down the noise from injectors reduced about 50%. What is this telling me? that sensor plate could be out of adjustment? not sure how to adjust? Thank you, Tim

[timchar]

I figured out how to adjust sensor plate, reduced as much as possible. Quieted injectors down maybe 50 percent, they are still engaged on the turn of the key. Tim

[timchar]

I just removed an injector and put in a glass, turned key and gas started spraying immediately before plunger was raised. I'm guessing its telling me my distributor is stuck wide open? Tim

[Tidybuoy]

Originally Posted by timchar

Vern, key on I pulled down the noise from injectors reduced about 50%. What is this telling me? that sensor plate could be out of adjustment? not sure how to adjust? Thank you, Tim

The injectors are supposed to stop completely. This is controlled by a piston/plunger in the center of the fuel distributor. That piston should move freely but slowly. It sounds like it is not moving down its chamber completely which could be caused by some corrosion in the chamber. There are also seals and metal diaphrams that are inside the fuel distributor. At this point, this is beyond my expertise but it is sounding like your fuel distributor may need some work.

Do some searching on this board for CIS. There's lots of threads with photos which will help you understand how it all works and what it's supposed to look like.

[timchar]

Vern, thank you for your expertise up to this point, I do appreciate it. I've been talking to Tony, (boy911sc), he's helping me out. Hopefully get this thing figured out soon..Tim