'74 Barn Find

mrdieseldude · 08-02-2014, 02:01 PM

I've been looking for a '74 for quite some time. #1 reason is because they don't need to be smogged in California (and I can't afford a long nose). '75's don't require smog either, but they do have a lot more smog equipment on them, so the '74 was preferred. I found one ('74 911S Coup) that had not been driven in 6 years, and while that was not ideal, there just ain't that many out there to get super picky. I had the PO get it to the local Porsche expert to address the safety things. This AM, I drove into the city to pick it up (about 60 miles) at the shop. It started with ease, and drove strong all the way home. In fact, I think it pulls harder than my '87 911 Carrera... gear ratio???

Anyway, I parked it in my yard to give it a wash. When I went to start it two hours later, it seems to only run on one cylinder... maybe two, but something is not right. After it starts (and thumps on one jug), the accel pedal has no effect.... I mean nothing. It will run like this for about 30 seconds and then stalls. I have had other CIS cars that would start easy when cold, and then be tough to start when hot/warm, but once they would fire, they would come in on all cylinders fairly quickly. This seems different. Any ideas? I am letting it cold soak for now, and will give it a try tomorrow just to confirm this is/or isn't that problem. Any suggestions before then are appreciated.

Michael

Arne2 · Arne2's Garage

Since you washed it, check for water in the distributor. Dry the inside of the cap out and try again.

timmy2 · timmy2's Garage

Did you lift the black lever between the seats to start it?

mrdieseldude · 08-02-2014, 03:03 PM

No water on the dizzy and yes I've i've lifted the black throttle lever. What I didn't mention is the engine and initially fires and runs very well I believe on the coldstart fuel. After a second or so that fuel is used up and that wants to run on the one cylinder.

Eli W · 08-02-2014, 03:28 PM

Could have easily gotten crud from sitting so long in the fuel system.

timmy2 · timmy2's Garage

Quote:

Originally Posted by Eli W

Could have easily gotten crud from sitting so long in the fuel system.

This^^^ is a strong possibility.

I would remove the main fuel line feeding the filter and run the pump to see what is coming out. If dirty change the fuel filter.
(use a clear mason jar to catch the fuel)

Then when the fuel from the tank is running clean, re-connect the main line and remove the lines to the injectors and WUR, then run the fuel pump catching the fuel in 7 jars and see what is coming out, and run again until clear fuel appears.

If the fuel was yellow and crud filled, clean your injectors, (Using the pintle lift method) and put it all back together when you know the fuel is clean.

mrdieseldude · 08-03-2014, 08:27 AM

Well gents, after an overnight cold soak, the car fired off effortlessly this morning and ran like it had just been tuned. This is the strangest warm start problem I have ever seen on a CIS car. I will check the resid pressures, but I sure would like to understand these problems better.

Michael

timmy2 · timmy2's Garage

Interesting.
Maybe it was water related from washing the car.
Does it restart after getting warmed up with a good run now?

mreid · 08-03-2014, 08:57 AM

I'm with Dennis. It's water related. You may have a cracking or unsealed electrical connection in the engine bay.

quattrorunner · quattrorunner's Garage

I'd bet you have dirt in the system. I hope it doesn't rear it's ugly head but my bet is it will. Fuel Distributor should be flushed and cleaned to be sure of nothing in the future. Also run fuel system cleaner if it's varnishy.
Maybe it was water on the ignition system. My car always has a miss right after a wash. When it drys up its fine.

Hil911 · Hil911's Garage

Could be a blocked Wur. There is a filter on the inlet that plugs and then the control pressure becomes the system pressure and the mixture is awful. Maybe check the control pressure.

Hil

Jgordon · 08-03-2014, 07:38 PM

Was the tank and fuel system flushed after its slumber?

timmy2 · timmy2's Garage

Must be working, he hasn't come back.

Larry_Ratcliff · 08-03-2014, 09:28 PM

Just a WAG (wild ass guess) but I am thinking it sat for 6 years so they did the minimum to get it up and rolling for sale. Change the fluids, drain the gas tank and change the filter.

I would start with the idea that there was plenty of funk build up in the gas tank and lines and that its starving for fuel big time with a clogged filter now...

just my 2 cents.

mrdieseldude · 08-06-2014, 08:38 AM

Quote:

Originally Posted by timmy2

Interesting.
Maybe it was water related from washing the car.
Does it restart after getting warmed up with a good run now?

I ran it up to temp yesterday, and let her cool for two hours, and it fired and ran like it was new. Maybe it was a water in the ignition problem, but because of a broken sun roof (these come standard with barn finds don't they

), the "wash job" was really more of a "sponge bath". Can these things really be that sensive to a few drops of water in the engine bay? The only way I can think of moisture getting to anything would have been through a steaming effect from a drop or two of water on a hot manifold?

Re: fuel contam - I'm thinking what I have in the tank now is OK. I am not seeing anything that would lead me to believe I have gunk/plugged stuff (but I am not ruling anything out... just thinking that this is starting to look like ignition).

Michael