First off thanks to everyone for all the previous help. I have a 305TPI in an 89'IROC-my problem seems simple yet I can't figure it out. Here is what I've got going on...

My oil is thinned down with a good amount of gas,the car is running extremely rich.I have a hot start problem as well as hard starting when cold. When it does fire up it smokes because of the excess fuel I guess. The idle will hover around 750 then kicks up to around 1500-2000rpm where it stays!I have changed the oil and filter,cleaned the distributor and cap,new plugs,wires are ok,tried another ecm,and have made sure I'm at tdc with no luck. Here are my questions...

I understand that these problems point to injectors leaking. But aside from the injectors,can a cts or something else make your car switch to open loop at idle and dump all that fuel into the oil? If my timing were that far off I think it would be very noticeable--the car seemed to run fine one day then like **** the next. How could a fairly sophisticated system like TPS change so much in one day-makes me not want to take it ouside of a few miles from home! Thanks everyone.

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*1989 IROC Z(White)
>305 TPI/700R4
>Flowmaster 3" Catback
>K&N Filters
>50k miles

 

Actually your symptoms point straight at the fuel pressure regulator diaphragm being ruptured. Pull the vacuum line off of the fuel pressure regulator (it is located near the back of the passenger fuel rail and is black in color if it is stock, and has a cap that is held on with 8 (I think) torx screws and has a vacuum port and line on it) and see if gas spews out of the vacuum port when you turn the ignition on. You shouldn't need to actually run the car if this is the problem. If the diaphragm is ruptured, as soon as you key the ignition to run and the fuel pump starts to run, gas will spew out all over the place..... This is a fairly common problem with TPIs (and other EFI engines) and is fairly easy to fix.

If it is indeed the regulator diaphragm, you can purchase a Holley Adjustable regulator and it will come with a new diaphragm (as well as the adjustable cap assembly). Or you will need to purchase a GM replacement one which is fairly expensive and may require buying the entire regulator even though all you need is the diaphragm. At least if you buy the Holley one, it will be adjustable and you can use it to tune a bit......

I also must warn you that you really shouldn't be driving the car at all with fuel in the oil. The fuel will severely limit the oil's ability to do it's job and could ruin the reciprocating parts and bearings in the engine. So get it fixed ASAP!!

Well, there's an idea for ya
Good Luck!!

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

 

When you say spewing everwhere from the diaphram,would that also contribute to leaking into the crankcase and oil? That is definately one thing I never thought of,and will check it out in the morning!

Thanks Matt87GTA,
Niko

 

Well, when the vacuum line from the plenum is on that port on the fuel pressure regulator, it will be allowing the fuel that is getting past the regulator diaphragm to go into the intake manifold and get sucked into the engine (if the rupture is bad enough, it will be pumping the fuel into the engine) which will make it run extremely rich. And that excessive fuel will find it's way past the piston rings and into the crankcase since the fuel pump tends to run a bit before and after the engine is running. It will also create a hard start condition since that excessive fuel will get the spark plugs wet and prevent them from firing properly. If you want to verify that your hard starting condition is due to an overly rich mixture, try depressing the throttle plates a bit while you crank the engine over if it won't start. If it starts easier with the throttle plates open, it is telling you that you have a rich condition during start up since the ECM will be providing the same amount of fuel for starting even with the throttle plates open slightly (if you floor the throttle completely during cranking, it will go into 'Clear Flood' mode and not provide any fuel. That mode is there for situations where the engine is flooded since you don't want any more fuel if the engine is already flooded). But with the throttle plates open during cranking, the engine will be getting a lot more air which will be leaning out the mixture and allowing it to fire. I have seen this type of problem many times with EFI engines and the car will exhibit the exact conditions you describe.

Good Luck!

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

 

Do us a favor and don't crank the car with the vacume line disconnected.

A fuel leak 3 inches from the distributer is a bad thing.

-- Joe

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/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
1989 Formula 350 4-bolt mains, Forged .030 TRW pistons, SLP 51010 Roller Cam, Comp-cams roller lifters,
Summit 1.5 roller rockers, World Products Sportsman II 2.02/1.60 heads, Edelbrock TPI Intake,
Cloyes Double Roller, timing chain, Mellings oil pump: 13.5 @ 100.23 MPH

Since close of track : Ported SLP runners, Ported Plenum, AFPR, Autometer 100lbs gauge, A/F ratio gauge.

http://www.joesperformance.com

 

I checked the regulator and diaphram this morning and there are no visible signs of leaking in that area.It seems that if the timing is off and the car is in open loop from a bad sensor it's possible,but this seems like alot of fuel to me. I have no codes,but can a bad cts or other sensor can cause this??

 

Potentially, yes. Likely? Tough to say.

First thing to try is start it, then pull the vacuum line from the FPR. If you get gas out of there, SHUT IT DOWN and you've found your problem.

If not, then you've got fuel going past your rings. Why?

Too much, possibly. Rings that haven't seated yet, maybe. Too much fuel because of a bad CTS (get your car on a scanner to see!), a leaking injector (if your injector leaks when you shut it off, this could easily be your source of fuel in the oil), etc...

Start with the easy stuff first: check FPR, scan to see what temperature the ECM believes it is while it's running.

 

Is your SES light on? If you have a sensor that is reading that far off, you should have the SES light on and some codes stored that you can scan and work with..... I still really don't think the CTS could cause the engine to run that rich even if it was reading way off......

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

 

I wanted to post an update and thank everyone.A bad cts can cause all the problems I was having.I couldn't believe one sensor could do all that,replaced the sensor(again)and everything cleared up.A miracle for sure,definately proves not to overthink things-

Niko

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*1989 IROC Z(White)
>305 TPI/700R4
>Flowmaster 3" Catback
>K&N Filters
>50k miles