84 3.2 with start issue but runs great

[jabb]

84 911 3.2 All stock

My car will not COLD start unless I use some starting fluid.
It will just crank but does not make any attempt to fire

This happened after the car sat for 4 months

I had to use the fluid about 3 times to get the car to run
Once it started it was fine and ran great.... no issues.

I doubt it is any type of sensor issue since it runs great and
I drove 700 miles from CT to new home in NC

I actually drove it about 400 miles before we stopped for the night.
The next morning I had the same issue. Would not start unless giving
it some starting fluid. Started up and drove 300 more miles no issues.

But still will not start.... Sits in the garage happy to turn over
but will not start. I did replace the DME relay today but did not change
anything. I am at a disadvantage because we just recently moved
My manuals are packed away and so are most of my tools.

I think it is some kind of fuel delivery problem but not sure.
I see there is a fuel regulator does this keep the system pressurized
for easy starting.

Any additional thoughts are welcome

Thank You

[ischmitz]

Hard starts after prolonged sitting is usually a sign of injectors sticking close. They won't inject any fuel. The starter fluid makes the engine fire and that vibration eventually gets the injectors going. Pretty common wit 3.2 that sit for prolonged times (several month). You can also tap the injectors with a screwdriver handle while cranking and that gets them going. Others have used a 9V block battery to "shock" them open.

This happening right again the next day is odd. Maybe you have a poor (aka shorted) CHT sensor. If the sensor reads short it suggests an engine at operating temperatures. This causes the mixture to be way too lean for startup. Once the engine is at temperatures the sensor reads less than 100 Ohm and a short sensor is fine and causes no issues.

The last thing you mention is the check-valve. If that is bad you would have hot-start issues due to fuel boiling in the rails with a hot engine. Not your issue from what you describe. But you could have a fuel pump on its way out. Similar to the injectors it needs some vibration to eventually make enough pressure. And the starter fluid firing the engine does that.

Next step is to measure your CHT with an Ohm meter. Or even simpler, once the engine is up to temperatures and idling fine pull the CHT plug. If that makes no diference the CHT is bad. If it makes the engine stumble (running very rich) the CHT is most likely OK.

Then do a fuel pump test (flow and static pressure)

Ingo

[jabb]

I jumped the fuel pump to make sure its running and at it sounds good
Will do a pressure test soon
If the injectors were closed driving 700 miles over 2 days should have loosened them up ??

Next test is the CHT......

I also removed the plug on the AFM when trying to start some have had success doing that
but it made no difference

[Nick Triesch]

Run a bottle of Techron from Pep Boys. Get the real thing, not the injector cleaner. Do this before all the other stuff. About $12.00 try it! then get it started and drive for 30 minutes.

[yelcab1]

Sounds like a head temperature sensor issue.

[ischmitz]

Noise of the fuel pump really means nothing. It still can have issues making sufficient pressure. I've had that happen to me and it was very intermittent.

Regarding the injectors the sticking effect I have seen is that they stick closed after the car sat for month. Once the engine runs and the injectors start to break free and open they are free and it is not very likely they stick again unless there is another prolonged downtime on the order of weeks or month.

However, I agree with Nick that a bottle of Techron is a good idea to clean things up. Maybe there is residue present that makes the sticking happen sooner.

[mysocal911]

Originally Posted by ischmitz

Or even simpler, once the engine is up to temperatures and idling fine pull the CHT plug. If that makes no diference the CHT is bad.

Ingo

Actually, if pulling the CHT had no effect once the engine is at normal operating temp,
that would indicate a shorted CHT input (pin 13) to the DME ECM, e.g. wiring, input
to A/D chip, or A/D chip itself.

CHT possibilities once CHT is disconnected & at normal operating temp:

1. CHT shorted - engine runs rich with black smoke (and hard cold starting)
2. CHT open - engine would have gone rich with black smoke during normal warmup
3. CHT too high of value - engine would start OK cold but run rich when warm, possible black
smoke, or at idle the engine would be surging.