Hard cold start

[pfarah]

Being a newbie, I've been taking a crash course on all things 944. Here's my problem: My 1984 is very difficult to start when sitting overnight. Once warmed up, she starts and runs fine. The following items have been performed:

1. Fuel pressure checked. 40psi once engine turns over,
2. Fuel check valve tested fine,
3. DME/fuel pump relay was replaced,
4. DME temp sensor was replaced,
5. Aux air regulator replaced,
6. All vacuum lines checked,

What's interesting is that when its hot outside, she usually starts fine however; the colder the ambient temperature, the more difficult the start. The engine will spin, catch, then die. Sometimes it takes me 5 or more minutes for the car to actually fire up and when she does, she sputters for a few seconds then settles in the correct idle speed. I've researched the forums and (I think) tried everything but obviously, there is a gremlin somewhere lurking about. I appreciate any help and thanks!

[kfray]

I would run these fuel pressure test.
http://www.clarks-garage.com/pdf-manual/fuel-01.pdf

[pfarah]

Thanks.
I'll try your recommendation.

[pfarah]

I've been away for a few days but tested fuel pressure at the specified intervals today; everything checks out. However, the car still refuses to start... Help.

[Rasta Monsta]

Check wiring to speed/ref sensors.

[pfarah]

Thanks!
It's ironic that you'be mentioned that because that's what I checked this evening.
The wires appear to be fine but the sensor tips did have a fair amount of debris on them upon removal/inspection. Here's the funny part; I dropped one of the sensor bolts by accident and ended up having to jack the front end to chase the bolt. It fell into the clutch bell housing and was fairly easy to grab from under the car. What's interesting is while I was down there, I snooped around a bit and found the vacuum line, running to the aux air regulator, was entirely severed as well as extremely brittle at the "Y". I'm planning on fixing it tomorrow and cross my fingers. As previously mentioned, I have to try to start the car after it's been sitting overnight so I'm being cautiously optimistic that the leaking vacuum line is the culprit. I'll post my findings after repairing this issue. Thanks again!

[Gawernator]

Coincidental, not ironic! Hope you fix the issue. Vacuum line would make some sense.

[pfarah]

I guess both terms could be used...
Well, I replaced the vacuum hose and its still happening so the list of potential culprits is getting smaller. I need to research how to test the fuel injectors for proper operation. Is there a ohms test?

[pfarah]

An update: I tested the resistance value on the fuel injectors; all tested exactly 2.4 ohms. I then checked all cable connections once again and this is where I found something interesting. The bracket securing both reference sensor cable connectors appeared in good shape, however; the bottem connectors (male and female) were not totally mated together. I verified that they snapped together and were secured tightly on the bracket and the car started on the first try! I will attempt to start her up in the morning as the colder air usually will cause starting issues. Will continue to report my findings...

[pfarah]

Well, I work up early this morning and...
she refused to start so I'm at square one again. I think I may need some professional help (mostly the car but maybe me too). Any other ideas?

[kfanazini]

Fuel injection temp sender? As I understand it, it acts like a choke during cold starts.

[pfarah]

Thanks.
I've already replaced the tenp sensor.

[pfarah]

I meant temp sensor...

[pfarah]

So this morning, same thing... This time, I injected some starter fluid just before the intake manifold, tightened everything up and she started right away! My question is: is my MAF out of adjustment or is something worse going on? Once she starts, the car runs great. Thanks for any input!

[pfarah]

Oops again...
I meant Air Flow Meter; I'm still in the process of learning this car.

[44CUPMASTER]

replaced the air flow meter they let go all the time .

[pfarah]

I'm going to replace the fuel check valve tomorrow. It appears that I'm losing fuel pressure when resting for a few hours. The AFM was replaced by the PO so I want to examine the lower cost items before this. Thanks!

[pfarah]

Well I've replaced the fuel check valve and still no dice...
I also tested the fuel regulator for vacuum leaks; I applied about 15psi of vacuum with no drop (@3-4 min). I believe my next option will be to remove the fuel rail and thoroughly clean all components. I've noticed a very small stain around injector #1's base so seal replacement is in order. I don't think that would prevent a cold start but it's on my list.
Any other suggestions? Thanks!

[Slam]

Maybe one or more of your injectors is not closing properly. If this happens the fuel pressure drops overnight as the injector(s) leak. It's amazing what a good cleaning will do for the injectors. For you Yanks, Witchhunter is the place to send them. Or just get a new set.

[Gawernator]

I'd rebuild... OEM injectors are pricey