Spring time afternoon starting woes

mrrolleyes · 05-06-2018, 05:35 PM

Prior to the weather breaking 60 the following has never occurred.

Seems like it could be the fuel accumulator but not 100% sure.

Morning time i leave for work and its a cold start... fires right up. Drive the car about 2 miles to work and park it for the day. It is sitting in the sun so its warm. Temperature is greater than 60.

Go out out leave about 9 hours later and it takes a good 6-8 seconds to start sometimes it feels longer.

Drive home and park the car and run out again and some errands with no issues. With multiple starts and stops.

Next morning cold start and its fine.

Seems like the warmer it gets the longer it takes to start in the afternoon. After 9 hours sitting its almost like a cold start.

I am trying to prevent this from getting worse when its 80+.

tirwin · tirwin's Garage

Could be several things but let’s start with the basics.

What year is the car?

Since you mention fuel accumulator I’m assuming it’s an SC.

If it is an SC, do you have fuel pressure gauges?

The first two possibilities are electrical and fuel system.

I tend to not think electrical in this case because your description suggests it only affects starting. Electrical failures induced by heat would tend to happen any time the temps hit the failure temp, not just starting.

If CIS, you need to run the fuel pressure tests.

mrrolleyes · 05-06-2018, 07:32 PM

Sorry 76 2.7

Its not electrical. This is something new with the climate getting warmer.

This issue was non existent as of last fall and over the winter when i drove it.

The only change was a turn down in idle. Obviously things break

tirwin · tirwin's Garage

Ah, a middie.

I'm not familiar with the CIS on the pre-SC cars.

Suggest you look at the chart on Jim's Basement Workshop:

911 CIS Primer - Troubleshooting

I know it says K-Jetronic but the basics still apply.

You said idle was changed. That was a change so maybe go back to that. Why was it changed?

If you've read any CIS troubleshooting threads then you know the drill. Run the fuel pressure tests as that will tell you a lot. Everything falls from that. If base settings are off, everything else is off.

That said, the temp above 60ºF suggests it is WUR related. I'm not familiar with the WUR for your year but that would be on my list to investigate. That's right around the calibration temp. Not uncommon for people to complain about differences in starting as season change like this.

What was your reasoning behind thinking fuel accumulator? Why would fuel accumulator be sensitive to temperature? Not saying it isn't that. Maybe it is temp sensitive somehow.

mrrolleyes · 05-07-2018, 07:46 AM

Quote:

Originally Posted by tirwin

Ah, a middie.

I'm not familiar with the CIS on the pre-SC cars.

Suggest you look at the chart on Jim's Basement Workshop:

911 CIS Primer - Troubleshooting

I know it says K-Jetronic but the basics still apply.

You said idle was changed. That was a change so maybe go back to that. Why was it changed?

If you've read any CIS troubleshooting threads then you know the drill. Run the fuel pressure tests as that will tell you a lot. Everything falls from that. If base settings are off, everything else is off.

That said, the temp above 60ºF suggests it is WUR related. I'm not familiar with the WUR for your year but that would be on my list to investigate. That's right around the calibration temp. Not uncommon for people to complain about differences in starting as season change like this.

What was your reasoning behind thinking fuel accumulator? Why would fuel accumulator be sensitive to temperature? Not saying it isn't that. Maybe it is temp sensitive somehow.

ill put the idle back up and test it.

its just wierd that the cold start in the AM is fine but after being outside for 9 hours it had an issue