73 911 E is dying

[cmcfaul]

Hello Long Hood Brethren:

My 73 E has been dying lately and running poorly at low RPM's. Coming off the hwy and stopped at a light it just slowly dies (sometimes). It does start right back up but it is becoming concerning. It's also slow to start when cold...needs a lot of cranking.

Engine is in good condition, MFI was rebuilt a few years ago. Fuel filter is a year or two old. I punched a hole in the tank screen many years ago when the car would die at high RPMs (fixed the problem). I replace the points with a Petronics (sp?) set up about 5 years ago and have not touched it since. Alternator, regulator cap and rotor are all less then a year old.

When re starting it slowly comes to life (does not roar to life like it should)

The fuel pump is original, should I start by replacing that? Open to suggestions.

May also have a slight fuel smell. All fuel lines are new in the engine compartment, others are original. 1/4 tank of gas (bad gas?)


Chris
73 911 E

[JimR]

Chris, did this problem show itself right after replacing the fuel lines? I mixed up (fuel pump outlet and tank return) mine after replacing lines. Similar symptoms. I am around this weekend if you need a side by side comparison.

[cmcfaul]

no, did the engine compartment fuel lines a while ago. I have not replaced any of the lines to or from the fuel pump.

[Grady Clay]

Chris,

I would be highly suspicious of contamination/rust in the fuel tank.

The best initial thing might be to buy a new filter screen fitting for the gas tank, wash out the tank and measure the fuel pressure before and after the big MFI fuel filter (this will tell if the filter is contaminated).

It is also possible that debris (larger than what would be prevented by a functioning tank filter screen) could have damaged the electric pump over the years.

Are you aware that Porsche published (in ’69) an incorrect fuel plumbing diagram for the hoses at the fuel filter console? That causes very strange symptoms and still rears its ugly head occasionally.

Best,
Grady

[cmcfaul]

I think I figured it out. I had partially blocked off the outlet to the evaporation tank (in the left fender) because the tank was was leaking and at DE's I would have gas stains running all the way down the left side of the car and on the caliper (which can't be good). I think this was causing too much back pressure in the tank as it would suck in air when opening the gas cap. I drove around with the gas cap loose and can feel the difference. The car had been feeling lazy and now is it's old self again.

So far so good. I need to figure out a better way to keep the gas from running into evaporation tank and let air into the gas tank as it is burned. Off the top of my head I am thinking a PCV valve (?). I would replace the evaporation tank but it seems like a gallon or more of gas would run into the thing when on the track (judging from the amount of sludge on the side of the car after a day of DE).

Chris
73 911 E

[Chris Tallon]

Interesting.....I noticed a bit of a gas smell last weekend while tracking the car at Cal. Speedway. I removed my Gas Evap. tank last year as the plastic was cracked and brittle and would not hold liquid any longer. The hose now sticks out of the body in the wheel well and I guess it drains at will (given gas smell). While checking over the brake pad wear, suspension, etc. with the wheels off after the event, I noticed that the gas that "burped out" during the track event spilled over the horns and other areas in the wheel well. I did not notice that the fuel had come out onto the side of the car though.

What are some of you doing in this condition once the evap container goes away? I'm now thinking it's not such a great idea to allow the gas to drain out without containing it.....Any thoughts? Thanks in advance.

Chris

[cmcfaul]

I get black gunk down the side of the car. It took me a while to figure it out. The caliper is getting wet as well. That can't be good for braking and as hot as it gets I am very surprised there was not a fire.

People driving behind me used to tell me there was a liquid coming off my car after a hard right turn. For a long time I had no idea what it was. Gives you an idea of how much gas can flow into that little tank.

Glad to know I am not the only one :-) just need a better fix

Chris
73 911 e