Second opinion--fuel isue.

944if · 07-28-2011, 08:20 AM

My early 1985 Porsche was parked for a little over 2 years b/c I intended to find a shop to do timing belt/wp.

When I parked it, I ran the tank pretty low (till the gas light came on) with the thought that, if the gas went bad, I could pretty easily dilute it.

2 years later, I went to start it. Replaced the battery and it cranks over. Carb cleaner in the intake and it'll fire a couple of times, so I have ignition and timing. I added a gallon of gas or so and went to fuel debugging (clarks garage FUEL 16).

All checks out there. Fuel pump fuse good, jumpered and audible (crank no start), primary coil voltage and activation. Speed sensor has ~400 Hz signal on it, ref sensor was IIRC around 60 Hz, and starter solenoid signal present.

I thought FPR might be failed high, so I cranked it with only 3 injectors connected.

I've never observed a tach bounce in this car (maybe because I mounted the tach upside down), but the fact that I get ignition on carb cleaner fumes suggests to me that it's a fuel and not computer issue.

I'm thinking bad gas, it's just surprising to me that it would stop it from running and I wanted to double check--because it could be FPR failed low, too, although I did replace this with one from a different car at one point. In any case, thanks for reading this far!

johnkoawood · 08:31 AM

Yes it is a fuel issue..

2 years ago, when it was parked, you should have drained ALL the fuel out of it.

Over time, the fuel in the tank, pump, lines, and injectors will turn to varnish (yellowish crusty stuff that could be seen in older carbeurated vehicles carbs / intakes over time)..

you need to verify you have fuel pressure in the rail (mount a fuel pressure gauge)..

If you have pressure in the rail, you need to pull and have flushed / rebuilt the injectors.. whitchhunter is a great cost effective service.

FWIW, when the light in my 88 comes on, there are just over 5 gallons in the tank, or at least there was when I drained it 6 months ago!

If you need a set of injectors, know to have worked when removed 6 months ago let me know... they are just sitting on my desk taking up space. I replaced them with new ones! email is easiest way to get ahold of me... johnkoawood (at) aol (dot) com

Guest765 · 07-28-2011, 08:59 AM

I'd try putting more than a gallon or two in and a bottle of heet or heat water remover before disassembly.

944if · 07-28-2011, 10:59 AM

Thanks, guys.

Yeah, I wanted to start with that confession--I really hadn't intended to leave the car that long, just long enough to find a good shop for the timing belt.

I bought a fuel pressure gage a couple years ago, but I've looked a few times for an adaptor to fit the 944 fuel rail and came up short.

My plan is:
--drain the tank (gravity through the bottom drain, maybe run the fuel pump to make sure it's cleared out)
--put 3-4 gal of fresh gas in.

If this doesn't solve it, I'll do an injector clean (see the 944 Tech Article on this site), and if that doesn't solve it...I'll be shopping around for a set of injectors.

Just over 5 gal is...impressive!

BoxsterGT · 03-08-2012, 01:40 PM

Came across this old thread............

I have fittings to connect to the fuel rail for a pressure gauge.

This is on an old 944 turbo fuel rail...........

Its only $20 plus shipping.

Len at Autosportengineering dot com

zedsn · 03-08-2012, 02:21 PM

after you drain the tank you can pull the fuel level gauge in the tank from the top underneath your hatch carpet and put a small rag securely on a close hanger and wipe any bad residue inside your tank that is left over and you can visually inspect your tank screen while you are at it for debris.