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Digitalchaos

Registered User
After going for a fast paced 10 minute drive, I stopped in a store for approx. 10 minutes. When I came back out and cranked the engine, it turned over a number of times then the cranking slowed. I stopped, and tried 2 more times before it started with a slight chugging.

The hesitation could be from worn starter bearings, but a friend noticed significant black smoke out the exhaust pipes while cranking.

This problem does not occur whenever the car has been sitting longer than maybe 5 - 10 minutes. I have never seen the black smoke before, but its probable that it has occured w/o my noticing during similar episodes.

Obviously a rich mixture on startup, but what would cause it? Along with this problem, it also seems to take longer than it should for my engine to start when cranking, warm or cold. There were no codes.

Thanks for your help..
 
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i had the same problem. I have a fuel presure guage on my car and i noticed that with the stock injectors they would have full pressure but when the car is off the rail would read 0psi after about 5 min. The rail should stay presurized for about 30min at least. It seems like the injectors are leaking...causing fuel to puddle in the head and cause a rich start problem...causing that black smoke. My car did the EXACT same thing. i swapped to new 42lb injectors and the problem was solved. Thats just my experience.

also...my crank sensor is stock, and from time to time when i pull my codes i get a code 211 in the memory. The crank sensor could be crapping out on and off while cranking, but this is just a guess. However the upshift arrow never comes on.

Anyways, try sending your injectors out to be backflushed for about 9 bucks each. I have this 3m fuel injector cleaner that works like a charm. Its a profession product and the can is hooked to the fuel rail..and the car is run off the can. The solvent in the can is some nasty stuff that cuts right through the gum inside the injectors and also clean the intake valves and such. Great product, but pricey for 30 bucks. You aslo need some special hoses and stuff, but most midas and meineke places do this service as well. I have a brand new full can if you need one, its not easily available to the public.
 
Thanks fastsc92. I was starting to suspect this especially after a search, as it takes a little longer to crank cold and the black smoke I saw today.

I was considering using an injector cleaning product, but I am concerned with damaging the plugs or even worse gaskets with one of these products. I had intended on using a product that is mixed into the gas tank, as it would be difficult for me to use one like you mentioned at this time. I have heard barrymans recommended, though I would like to know more to reassure how safe it is.

I also considered that it could be the fuel pressure regulator. Where exactly is this unit in the SC? A pic perhaps?

Thanks again..
 
the regulator is on the fuel rail..in the back right behind the return plenum where the ic tubes go into the lower intake. I have an extra stock unit if you think yours is bad.

as for the cleaner...anything that gets added to the tank, i wouldn't think it would have a shot at working. This 3m stuff is top of the line and is what the pros use. Its not hard to hook up, you just need one hose which connects the can to the fuel rail. You unplug the fuel pump and ran the car on the can until the car dies (about 5 min). I've done it to my friends stang and it worked great.
 
Might also be your cam sensor beginning to go. I would imagine if you have never changed the crank sensor the cam sensor would be in the same boat. Cheap fix relatively and easy to do. Disconnect the electrical connection to it...remove the 2 screws and replace with new one and hook it up. 10 minute job. Located where you would expect the distributor to be.
 
I should have also added there is a slight smell of gas upon some startups.. I have not detected it often enough to remember if it was specific to warm or cold.. could be both.

I found a post detailing the use of an LED test light to detect proper cam sensor operation, would this detect the beginning of an error?

Thanks for the helpful info..
 
Ok I located the FPR but I see it is underneath what looks like the intake plenum. Is there a way to check this unit w/o disassembling the intake, and eliminate it as a possibility?

Could the FPR cause all of the same symptoms as leaking injectors.. including a rich mixture at startup?
 
Digital, I read on a post somewhere that if you pull the vacuum line going to the FP Regulator, that if fuel comes out of it then it needs to be replaced. You would THINK that if it is leaking that you MIGHT be loosing fuel pressure out of it. Replacing it might not be a bad idea if it never has been, and if you end up pulling out your injectors cause it will be right there...
 
Yes, if the diaghram inside the FPR is compromised it will leak various amounts of fuel into the crankcase through the vacuum hose.

I was able to locate the regulator last night, but unfortunately I observed it to be behind the supercharger under the intake plenum coming off the lower IC hose. This not only makes the FPR likely impossible to access without removing the top half of the engine bay, but it also looks like the vac hose can't be removed from the FPR.

I wonder if removing the windshield cowl will allow access to the vac hose connection on the aluminum piping..
 
just pull the blower..its 3 bolts, loosen the collar nut, pull some hoses..and everything comes off together. Then the reg can be seen and checked. I doubt that is the problem. Just pull the hose off the intake side from the reg. and see if there is gas in there. If there is then its bad, but i think its fine. The hose comes off both the reg and the intake. I would still put my money on leaky injectors, that depressurize a little and cause a rich mixture at restart.
 
I pulled mine by way of removing the cowling (Wiper arms and 6 screws). There is huge amounts of room to access the FPR, at least on my 90', with it removed. That thing (Cowling) should be on a hinge on our cars. :rolleyes: What about Duffy's cam sensor theory? Can that cause this if the injectors are pulsing at the wrong time, essential flooding the engine possibly??
 
You can see it under the 3 vacuum lines about 1/3rd the way from the bottom of picture....this is with the cowl removed...Ooops, and wiper motor assembly..
If it is an injector, then it will be easier with the SC/Plenum/Adapter Assembly removed as that is how I replaced my injectors (Which wasn't my problem - IAC)...
 

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if it was a cam or crank sensor problem then it wouldn't run right during cold start or idling for that matter. He states that he only has a problem after its been running and shuts it off for a matter of 5 min. I'm telling you i had the exact same problem and it was leaking injectors. Once i had mine professionally cleaned...they were fine, and the problem went away. I'm just being logical here. If it was a crank sensor or cam sensor, then it would happen while driving and idling as well. Just my 2 cents.
 
Thanks for the info bob, I was thinking about removing the cowl also. I also am leaning towards the injectors or perhaps FPR as opposed to an electrical issue, but these are still possibilities.

The exact symptoms I seem to be noticing include:

Extended cold crank times - this means my engine seems to crank over more than it should before starting. How long? Maybe 6 seconds. Multiple key attempts make no difference. I don't know how long it should take as I have not yes recieved a response to my other thread about cranktime, but I am guessing it should be 1 or 2 seconds max.

Slightly extended warm crank time and periodic slight chugging during last cranks - this essentially means that it also takes about the same crank time to start when warm, if slightly less. I also notice that if its been off only for around an hour or less, the engine tends to 'catch', 'chug' or basically not rev to life like a normal cold start. It is not severe.

Rich mixture when warm start - This is not my observation. A friend noticed the other day there was very black smoke immediately after a warm restart. The smoke lasted maybe 3-5 seconds, and was partially during cranking. I don't know if it occurs every warm start, or even if it occurs cold. Its only been looked for once.

Very slightly rough idle - I have solid motor mounts, w/o them I might not even notice this. While idling, there is very slight roughness which can be felt every 1/2 to 1 second when the windows are up, the car is sitting still, the radio is off, and you are paying attention. It is not enough to observe any difference in the tach. Could easily be normal for a 96k engine.. plugs/wires new and proper.

This is all I notice. There are no codes. Cylinder balance test passed 4 times. I want to rule out the FPR because I don't think it could leak fuel into the cylinders, which seems to be whats happening to cause that black smoke. This leaves the injectors and a possible randomly bad cam sensor signal, at least to my knowledge. I think I can test the cam sensor with an LED test light. If I can find enough evidence against the injectors, I will likely run a bottle of Barrymans through the gas tank and look for a difference. If I can definately narrow it to the injectors and all else fails, I will run a bottle of cleaner through the fuel rails.

Thanks again for the help everyone!
 
Was just asking Fast92, yeah that sounds logical and I wasn't sure on the cam sensor, so thought I'd throw it out there and ask..
 
hey digital...

I know our problems with our cars are very similar....and I've been thinking lots about the both of em..... for mine I am thinking the TB..now for you

If I where you...just for process of elimination(takes time but cheap)I would change my 02's..change my fuel filter...dump Slick-50 fuel treatment into half tank 92 gas...

If she still persists...I would take the Blower off...buy new TB gaskets...inspect the TB sensor...Inspect the Blower itself for leaks...inspect the intake manifold gaskets...fuel reg...and at this time...I would also take off my fuel rail...and send the whole rail with injectors in to be refurbished!!!!

Also while the Blower is off...u can peak at all the hoses and valves that live behind the SC!!!!

I am sure You probably have done most of this already and I know this is VERY time consuming....but compared to shop prices...this will cost u next to nothing...and u can rule out alot of things that can cuase an Intake leak....I hope I have returned the Favor alittle bit!!!

Good Luck
 
Ok I just pulled the hose to the FPR to eliminate it as a potential source of this problem. There was no evidence of fuel upon immediate inspection, I turned the key to on and there was no fuel, I started the car and ran it for a brief period 3 times, there was no fuel. The FPR looks relatively new. I believe it can be eliminated as a problem.

This leaves the injectors then? As I said, it runs rich upon warm startup and sometimes slightly stumbles, and crank time is slightly extended.

I guess I am going to try some fuel system cleaner.

Other thoughts anyone?
 
I just finished a tank of Chevron Techron concentrate; it smoothed out small idle irregularities but a day later it has made no impact to cranking time.

Additionaly, the problem seems to be worsening slightly, at least when cold.

I am concerned that with continued oil contamination by fuel likely due to long cranking, excessive wear will occur to the cylinder walls.
 
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