Warm start issues

[Porchcar guy]

HELP PLEASE !!! ...My 79SC has had many starting issues over the past 8 months of owning her but usually only having her on weekends to see what real life does to the changes. She originally would not cold start very easy if at all. According to the mechanic, the pressures are now inline with spec. This after changing/rebuilding the WUR, the Fuel Distributor and lastly the Injectors.

The problem now is what I call warm start. After turning her off and trying to start around 20 minutes to 1 hour, she just feels like she is getting no gas...cranks but no trying to start. Sarts up cold first crank..same with hot start...first time.

Last night went to a store and came out after 30 minutes. Cranks over but no feeling of starting - tried 10 times... changed the fuel pump relay...pushed her down a short hill and popped second...no start ..just bubbububub. Had a guy push me and same result. cranked her again 5 times for about 3 seconds each. Sixth time started right up.

HELP !! Iam lost over this...Could it be vapor lock ? Very frustrating !!!

[rching]

I have a 73.5 CIS and it fires up easily when cold and when hot. If I let her sit, I have to crank it 5 -6 times and she'll start up again. I had it checked and it seems like the pressure side of the CIS loses pressure. I haven't found out why yet. So, if it cools down, the WUR gives it gas and it fires right up. When it's hot, the pressure is still high enough and it starts right up. But if you leave it just long enough for the pressure side to lose pressure, it doesn't want to start but will, for me, at 5-6 tries. Just my $.02. Don't flame me!! : )

[Porchcar guy]

Why would I flame you...My symptoms are similar so we must be brothers from another mother :=) ... hate feeling like I am stuck.Last night I was ready to call AAA to tow me but my stubborness said...try it again .Usually it sarts about the 6th time but not last night and now I have a tight low back from pushing the recalcitrant girl !

[tazzieman]

Bad fuel accumulator is a distinct possibility.

[boyt911sc]

Check the residual fuel pressure. Three (3) most common culprits for residual fuel pressure are:

1). A leaking (FA) fuel accumulator.
2). A leaking FP check valve.
3). A leaking FD pressure relief valve.

All the above could be bench tested and don't replace part/s unless verified defective. It would help others too if you post the values of the fuel pressures your mechanic got during the repair. OK or 'within spec' description is too vague. Keep us posted.

Tony

[CharlieB]

Do a search for "primary fuel pressure regulator". Read the threads and look at pics. Simple to remove and clean the regulator in the FD. Next look into a new fuel pump check valve if problem persists.

[Porchcar guy]

Guys, Just sent an email to my mechanic with your responses..THANKS ! I will let you know what the followthrough is as I am really wanting a car that starts everytime !

[Joe Bob]

A pressure gauge will be your friend. I've had two CIS cars have hot strat issues. Bothe times it was the fuel pump check valve. 20 bucks last time I checked.

[T77911S]

+1 on what tony said.

not sure what rching meant by the WUR gives it gas.

what generally happens is it cools down enough for the CSV to get it started.

with my car, i have also found that after rebuilding the starter, it turns over much faster when hot, which can help......but dont go spending money just to replace a starter thiking this is the fix.

[Porchcar guy]

Guys,
Just remembered that while cranking and not starting, the tach was jumping around at 4-5k. Don't have any idea if this is important as I never noticed it before. Thanks for all your replies !!

[Rednine11]

Originally Posted by tazzieman

Bad fuel accumulator is a distinct possibility.

My 911 did this. FA was the problem

[ossiblue]

Originally Posted by Porchcar guy

Guys,
Just remembered that while cranking and not starting, the tach was jumping around at 4-5k. Don't have any idea if this is important as I never noticed it before. Thanks for all your replies !!

I've never witnessed a tach bounce so high under starting conditions. If in fact your tach is jumping that much, it could indicate the problem is with the ignition rather than the fuel. Further, it seems odd that your car wouldn't start with a bump start as the fuel pump should pressurize the system as soon as vacuum is detected in the intake via the rotating cylinders. However, trouble-shoot the obvious first--your residual pressure. If fuel pressures check out, follow up with ignition.

[Porchcar guy]

Ossie,

The car was on flat land and I could not push to get it fast enough that second gear would pull it in to starting. Probably should have gone to third gear but I was pushing then jumping in and needed to be fast. It was quite the sight to see :=)

Spoke to my mechanic and he also said that it may be ignition related. Car goes back on Friday to him. I will keep everybody in the loop as to what transpires !

[ossiblue]

It doesn't take much to activate the fuel pump via the air sensor switch, that's why I suspect ignition. If it happens again, try opening the air box (with the ignition switch "on") and pushing up gently on the plunger inside--that will start your fuel pump. If you immediately hear a squeal, your system is pressurized and the residual pressure is likely o.k. If you need to wait a few seconds before you hear a squeal, the pressure is suspect. Either way, now try to start the car. If it doesn't start now, it's likely an ignition problem as there is fuel going into the cylinders.

[Porchcar guy]

Thanks Ossie,
I can hear the pump running when I turn the key to on. I will try the plunger tonight after I drive her and let her sit for 20 minutes. As I said above, she cold starts first crank and hot starts the same....

[ossiblue]

Originally Posted by Porchcar guy

Thanks Ossie,
I can hear the pump running when I turn the key to on. I will try the plunger tonight after I drive her and let her sit for 20 minutes. As I said above, she cold starts first crank and hot starts the same....

Okay, you've got another problem there--your pump should not be running with the key in the "on" position unless you jumped the terminals at the fuel pump relay. This does not affect your starting problem necessarily (unless your injectors are leaking), it's a safety issue. Once you get the starting situation cleared up, get the fuel pump circuit fixed--it's probably a bad relay or the wire to the air sensor has been disconnected.

If your pump is actually running when the key is "on", then the system is being pressurized and that should take care of a low residual pressure situation but go ahead and run the plunger test to ensure fuel is at the injectors. It's beginning to sound more like an ignition problem the more tidbits you add. Don't forget to get the pressures checked regardless of what you find.

[T77911S]

if the connector is removed from the back of the AFM, it will run all the time, but that will not help if it vapor locks. my pump runs all the time and i sometimes have the hot start issue, although the faster starter speeds has helped that.

lift the plate as ossi has said, then see if it starts

[Porchcar guy]

bump

[boyt911sc]

Originally Posted by Porchcar guy

bump

We need feedback. This is a two-way communication. What has your mechanic done so far to solve the problem? Or the car still sitting at home? Keep us posted.

Tony

[Porchcar guy]

Guys, sorry for the delay. Mech is out of town, just found out this am before I took her to his shop so she is still sitting in the garage. His other mechs won't touch her this week so I have her for now. I plan to try some of the things discussed here over the weekend when I have time. I own a retail shop and work 6 days a week so Sunday is my day to do stuff :=). Been reading Bentley as my homework.Thanks for all the help and I will follow up next week after he looks her over. Going back to my original premise...she starts cold first time and hot starts first time...was going to take her yesterday to work...started up first go and pulled out of the driveway. Heard a clank and saw a rectangular something on the ground behind the car. Picked it up, it was the mirror glass from drivers sideview. Small chip in corner ...Grrrrrrr....Pulled her back in and drove my Camaro...gosh, if wasn't for bad luck ...there would be no luck at all !!