SC Warm start problem, after at least 90 minutes sitting
 

Hello all,

I know CIS warm start is a FAQ but I really did search and didn't find anyone with exactly my situation. Here it is:

78 SC with 37000 miles. Starts immediately when cold. also starts immediately within 30 or 60 minutes of being parked. However, getting closer to 2 hours, it will crank and crank for 45 or 60 seconds before it starts. It does always start, eventually, though. The timing seems to depend on how cold it is, if it's colder it won't have to sit as long before having trouble starting. It seems like if I pump the gas pedal a bit it will start more quickly, but it still cranks a lot during this 2-5 hour time window. If the car has been sitting more than 5 hours or so, it starts fine again.

Most of the people with similar problems seem to have issues within 5-15 minutes of shutting down the engine, where mine takes more like 2 hours, so I'm wondering if that indicates something different.

Thanks in advance for your help,

Pumping the gas peddle won't help, but it's usually either or both the fuel pump check valve, or the fuel accumulator.

+1

mine does the same thing. if you turn the key to ON, then lift the air flow meter plate for about 3-4 sec., it should start without pressing the gas pedal.

start problems
 

After that 2-5 hour period, try putting the ignition to on, reach in the air box and push up on the throttle plate for a second, hopefully youll hear the fuel squeal noise. Then try starting it. If it starts easy, I would guess its the fuel accumulator or the fuel pump check valve. The only way to know for sure is to do a fuel pressure test. You can buy one from JC Whtiney for about $60. Just make sure its for CIS ignition if thats what you have.

Thank you, I will try the throttle plate lift. Then I'll do the pressure test if necessary. Thank you everyone for your input.

CIS troubleshooting........
 

Andy,

Need a little bit of info:
1). You said it starts easy when cold, does it start immediately after sitting overnight? How many times (start) in the morning to get it running?
2). I re-read your post several times and I'm not sure I'm getting a clear picture of the problem. Without knowing the fuel pressures, most of our suggestions are based on conjectures. This may not be an effective way but sometimes people get lucky.
3). How long have you experienced this starting problem? Just recently? When the fall temperature arrived?

Thanks, Tony

The problem is related to one of two things - fuel accumulator or the check valve in the fuel pump. I had same problem with mine - driving me crazy - Embarassing when you are at a restaraunt and a bunch of kids come over to check your car out when you are getting ready to leave. Need I say anymore.

Steve

Had same problem. Fortunatelyfor me fuel accumulator was the easy and cheap fix. try it and you may luck out.

an easy way to test your accum. is to unscrew the bottom hose and see if fuel is leaking out the bottom of the accumulator.

Don,
Not to be stupid but is fuel leaking GOOD or BAD?
Glenn

BAD. It means the accumulator has a ruptured diaphragm; the accumulator must be replaced. I just did this on my '78 early this summer - solved the problem.

Jerry M
'78 SC

Where do you find the accumulater? I can not find it in my Bentley manual.

I had the same problem on a Carrera 3.0. The fuel pump had already been replaced so I fitted a new fuel accumulator. Starts first time hot or cold every time

on the left side of the engine bay, just north of the fuel filter. it looks like some sort of military surplus thingy

replaced mine 2 months ago. did not enjoy the process but had all back together in an hour or so

im wondering if the amount of time it takes for the no-start problem to develop -- 2 hours -- is directly related to how bad the fuel accumulator is. if its slowly loosing pressure, then the fuel is vaporizing slower....if quickly loosing pressure, fuel vaporizes faster and then you run into pizza shop for a slice and come out 15 minutes later and no start

i think what happens is it gets a vapor lock because of heat and a lack of sufficient pressure. then the car is too warm for the cold start valve to come on and help start it. lifting the plate primes the system again. i guess starting does not raise it high enough to bleed it or it takes a long time.
just another not, my brother had my car before me, he replaced the WUR for another reason and he said his hot start problems went away. just letting you know this can also cause it although it is not the common fix

Until you get it fixed, try just short duration pulls on the key; say 2 seconds or so, instead of one 45 second one.

You're describing the same problem I experienced for quite a while on my 3.2 motronic ('85 Carrera). After doing a fuel pressure check, I found that residual pressure was dropping down to 0 after about 5 minutes; it should remain at 14 lb 20 min after shut down.
On mine, was either leaking injectors or bad check valve on the electric fuel pump. Because it would stall out a few times after starting it if I pressed on the gas, that made me believe it was flooded from leaking injectors.
Pulled injectors & sent them for cleaning. Received them back yesterday & residual pressure is now good. Will button up the rest of the engine tonight & take it for a spin... I think I've solved the problem; if not, I'll focus on the check valve on fuel pump.
regards,
jlex.

Not Exactly..........
 

Don,

When you detach the bottom fuel line of the fuel accumulator, there will be fuel dripping out from the accumulator and from the detached fuel line. Why? Because the botton fuel line is attached to the main fuel return line. There will be always fuel in the lower chamber of the fuel accumulator (good or bad). You need to pressurized the delivery line to the fuel accumulator to check the condition of the diaphragm. Unplug the bottom port (FA) and cap the detached line.......run the FP for a few seconds and observed if fuel will drip out from the bottom port of the FA.

Tony

if this is done and fuel leaks from the bottom, the accumulator is bad?!?! i'm having the same problems and want to fix it.....its getting annoying