Another hard to start issue

[944 S2]

Ok today I got some stuff done including my fuel pressure regulator. I was told that's probably the issue with my starting problem.
Car cracks for a while till it finally catches, runs rough for 10-15 sec, spews dark smoke, then we're all good. Idols fine etc. The thinking was too much fuel. Any thoughts? Car has 64k miles. 1991 S2.

[dgcantrell]

Probably the coolant temp sensor.. Dark smoke means it's running too rich (too much fuel) like you mentioned.. It should be located near the water hose connection on the head. It's a cheap and simple swap.

[944 S2]

Got a sensor on order. Can it be swapped out without loosing coolant? Any special procedures?

[dgcantrell]

You may loose a little but it's up there hiding just behind that short section of rubber hose that connects to flange on the head up in the top of your picture. You could drain the radiator and not lose any coolant. You'll still need to open the bleeder bolt on that flange while you're putting the coolant back in to get most of the air back out.

I looked at the sensor location on my S and it looks to be a tight squeeze but certainly doable with a wrench as it's just a few inches behind that short hose. The fuel line from the front of the rail to the regulator looks to be kind of in the way. You might take the regulator and the hoses loose from the rail and get a lot more space to get a stroke with the wrench.

[944 S2]

On the back of the engine by the fuel reg? I just got the reg to stop leaking when I replaced it, so I'm hoping I can get to the sensor with removing the fuel reg. It was a bit of a pain to install.

[Pauld_94S2]

The DME temp sensor is under the gooseneck at the front of the engine where the bleed screw is.
Look under the short black hose on the right that connects to the gooseneck.
Or you can find it below and to the left of the fuel pressure damper in the front.

Very easy to get too, shouldn't take more than 10-15 minutes even if you have to get your tools!

[dgcantrell]

Nevermind what I said about the fuel line hoses on the front regulator, they are not in the way. As long as the air filter box is off, you have a straight shot in. Here's a pic showing the location. It's just a couple or three inches behind the short coolant hose.

[944 S2]

Well I just replaced the coolant sensor and.......no change!
Any other thoughts? Would a leaky injector give me this trouble. Once started a little rough for a few seconds then it's runs great.

[944 S2]

Fuel check value? Someone recommended. Anybody had issues with their check valve?

[944 S2]

New fuel filter and check valve are in. Check for leaks, then see if it helps with my starting issue!

[944 S2]

A pic for those with an S2. Check valve screws into fuel pump directly. I removed pump to make it easier.

[944 S2]

Well still no change in the starting issue. Need help guys...any idea so on what to check next?

After I do get it to start it runs good. Shut it down and starts right up. Took it for a drive and got the engine warm. Shut it down and starts right up. Waited 15 minutes then back to hard to start.
Oh and there was white smoke on the initial start up.

[kdjones2000]

Did you also replace the fuel pressure damper as well?

[944 S2]

Originally Posted by kdjones2000

Did you also replace the fuel pressure damper as well?

No although I did think about it. My understanding is its purpose is to level out any sinusoidal pulse from the regulator. Also would'nt the car run rough all the time if it were bad?

[Pauld_94S2]

Check the fuel damper (front), and regulator (rear); they are known to have the diaphragm rupture and allow raw fuel to leak into the intake.

Real easy test, pull the vacuum hose and see if any fuel comes out.

[944 S2]

Originally Posted by Pauld_94S2

Check the fuel damper (front), and regulator (rear); they are known to have the diaphragm rupture and allow raw fuel to leak into the intake.

Real easy test, pull the vacuum hose and see if any fuel comes out.

Well you might be on to something here. Look carefully I just caught a pic as the fuel is dripping from the vacuum line on the fuel damper.

[dgcantrell]

Bingo.... I think we have located the problem..

[944 S2]

Well after starting the car with the damper vacuum hose discontented I found the fuel drips almost became a stream. Next day I Plug the hose and started the car. Well it started right away with no smoke!
Ordering a new damper!
Thanks everyone who gave input and a special thanks to Pauld_94S2 I think you nailed it!

[Pauld_94S2]

Great to hear that, now go drive it!

[Project560]

Thanks to Pauld for the push for me to check my fuel damper vacuum hoses too. I knew that should I check them, but I just haven't gotten to it. I didn't have fuel leaking out, but the hose had a very small crack once I got really close to it. Replacing the hose didn't solve my rich smelling exhaust, but I am better off for finally checking it. Thanks!