Start Up After a Looong Rest, Running Rough
 

I started my 944 up after it sat for just under 9 years. I put it away ages ago because something was wrong, but if I'm honest, I don't remember quite what. I want to say it overheated, but :confused:

Before starting I replaced the spark plugs, gave it fresh gas and hand-primed the oil pump. I've also done (to the best of my abilities, which are mediocre) a leakdown test that appeared ok. I chased down some electrical issues that were causing a no-start condition and then I fired it up:

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It's running pretty rough. Feels like a washing machine from inside the car and has a very putt-ery sound to the exhaust. I'm wondering what the forum thinks it sounds like?

Left over effects of bad fuel. The FPR or FPD could be sticking as well as the injectors. Try gently tapping on them while running to see if they free up. You should also change the fuel filter.

Make sure your plug wires are in the right locations.

Ethanol-added gas is the worst. Probably one of the biggest con-jobs in history but I digress. You cannot let it sit for more than a few months as it will turn to s**t. When trying to re-fire a car with ethanol gas having sat in the system for more than, say, a year, you need to drain as much of that s**t out of the system as possible. Draining the tank and replacing the fuel filter is easy and the most effective thing you can do. You can drain the fuel rail without having to remove it but there will still be a small amount of fuel in the system even then. Once you get everything drained, reconnected, and a new filter installed, I'd jump the fuel pump portion of the DME and let the fuel pump run for a minute or so to flush any crap in the lines back to the tank to be filtered out. Plus it pushes fresh fuel though the system to help dissolve any jelled fuel residue in the system. Adding some SeaFoam Fuel and Oil System Cleaner is also recommended. Put the DME relay back in and fire it up and let it run till it gets warm and starts to run better.

I've replaced the fuel filter, replaced all the hard and soft gas input lines (because the fuel filter was rusted solidly to the old lines), had the injectors cleaned by witch hunter, drained the gas tank and filled it full of fresh gas. We don't really have ethanol gas where I live, but in any case I've done about as thorough a drain as one can do. Didn't clean out the rail itself, though.

I could see FPR being the problem, haven't touched that. I'll double check the plug wires, it's be great if it's that easy :)

I think it's the fuel pressure regulator. According to Clark's Garage, I should expect 36psi when stopped and 29psi when running. I'm measuring 52psi and 48psi, respectively.

I was failing the fuel pressure leakdown test, but I tightened up the gas line to rail connection and now it's sitting at 50psi after 20min.

Signs point to a new FPR.

Rear of the cam tower is leaking oil something fierce. I assume it's the cork gasket - anybody every manage to replace one of those without pulling the cam tower?

Totally doable. I use gorilla snot on the gasket and loctite on the bolts. Tighten slowly and carefully. . .don't crush the cork.

What's gorilla snot?

I'm guessing Yamabond 4 or Permatex Aviation sealant.

Gorilla snot= Yellow 3M weather strip adhesive.

I gave up on the cork gaskets years ago. I use the cork gasket to trace out mine on thick gasket paper and install with Permatex Aviation hi-tack adhesive to hold in place. It's been eight years, no leaks.

After sitting for a long period the injectors could be stuck. Pull your plug wires and listen for a difference. Use a long screwdriver and place the blade on the injector body and bump the screwdriver handle with a hammer a couple of times. Sometimes you can jar an injector loose. You will know if you are successful if the engine begins to run smoother.

Good luck.

I put the new fpr on and fired it up.

The good news is that my fuel pressure is bang on spec. 36psi with engine off, 29 with engine idling. The bad news is that it still runs rough.

I pulled the plugs, which are brand new, and 1&2 were clean as a whistle, while 3&4 were pretty sooty. I checked the spark, and the tester lights up for both 1&2, so I believe they are getting zapped. I double checked the timing belt and the marks all look like they line up.

That leaves fuel and compression. The injectors are freshly rebuilt, never fired since sending them off. How shall I go about testing them?

Don't overlook a bad oxygen sensor.

Curil K2

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