I am haveing a few problems on my 86 IROC....all sensors are new, all relays are new, almost everything under hood is new....(car was is real bad shape)

1: my fuel pump comes on after the car is turned off, and key in hand. I have changed the relays & plugs (most were bad anyway) and oil pres. switch, is there a 2nd oil pres. switch for the fuel pump? I'm having issues with MAF burnoff, I've asked about this befour, and still chaseing after the problem, now the pump runs longer than it did befor.

2: The car is running pig rich with new injectors (22lb), new prom (AC for a 89 350) new computer, and new MAF.

I have been working on these for a little bit, so any help is helpfull.

thanks,
joe

 

The first problem is thinking your car has a 350 engine. It doesn't, at least not from the factory. Check the 8th digit of the vin number, If its a f, like it will be, and you are certian nobody did a engine swap on it, then its a 305 tpi. If this is the stock 305, then your rich problem is going to most likely be them injectors. 22lb/hr is for actual 350 tpi's. You need 19lb/hr injectors, and a 305 ecm/prom. Ecm you need is a 1227165. Call a dealer and get the proper prom for it, cause I don't remember it's number. After you get all this done, go over your basics. Plugs/wires, tps voltage, timing, etc. Good luck!

 

I put in a 89 L98, and everything that gos with it.

 

Alrighty then. Well, Now I would say do a fuel pressure test on it. Make sure the pressure isn't too high, possibly from a bad fuel pressure regulator.

 

The Code 36 is likely being caused by the fuel pump running after shutdown. Search some old posts and you'll find the full explanation.

The usual cause is the auxiliary oil pressure switch. You should be able to disconnect the large tan wire from the oil pressure switch and isolate it. Teh fuel pump will still run via the relay and you car should run normally. If the situation changes, and the pump no longer runs on (twice) you probably should replace the oil pessure switch. If the situation does not change, the relay and its wiring are suspect.

 

I did change the oil pres. switch (not to say that its good, its not like you can get a bad part) should I run the car with the TAN wire disconnected?

the fuel pres. is at 48PSI

 

Yes u can run the car as Vader described

Fuel pressure line off should be 43.5.

later
Jeremy

 

the PSI reading I got was with the vac. line hooked up and car running. should this be changed?

 

Well no wonder you're running so rich... 48 psi with the motor running and vacuum line connected is really like running 51 or 52 psi (it will change with changes in vacuum) Which is also like using ~24lb/hr injectors.

Set the fuel pressure to 43.5 psi with the motor running, vacuum line dis-connected, then go for a drive to let the ECM re-learn.

 

also disconnect the battery and step on the brake pedal to drain any voltage capacitance from the system.

 

I will check all this by the weeks end (if not raining) and I will post back.

Thanks for all the replys,
joe

 

After unpluging the tan wire (I think I got the right one) the fuel pump comes on for 1 sec. (after turning the car off) then gos off, is this right?

Fuel pres. is at 45 w/vac. line off and car still running, still pig rich, what should I look into next?

 

Why did you unplug the tan wire? I'm not sure which wire you're talking about, maybe the one for ECM timing control?

It sounds like your fuel pump is working normally.

If you have an AFPR turn the fuel pressure down to 43.5 psi.

 

The only relay I can think of that activates on shutdown is the MAF burnoff relay, which activates for about one second.

When you hooked everything up, are you shaw you didn't hook the wiring for the MAF burnoff, into the fuel pump somehow?

I know it sounds strange, just trying to think of things that activate after the car is shut down.

 

[QUOTE=mnorton;3103804]Why did you unplug the tan wire? I'm not sure which wire you're talking about, maybe the one for ECM timing control?

I unpluged it per Vaders post, fuel pump used to run for long time (about a min.)

Aussie GTA: I dont think so, because when I did it I changed the plug ends too, and I did them one at a time.

Also the motor cranks about 10 x's befor it will start, even when hot.

 

The tan/wht wire is a 12volt supply connected to all the following:

1. Fule pump relay
2. MAF
3. Oil Pressure switch
4. Fuel pump
5. ECM

Which:

1. If you disconnect it at the Fuel pump relay the MAF, fuel pump, and ECM fuel pump control won't work until the pressure switch closes which causes extended crank times.
   
2. It'll run if you disconnect it at the MAF, but not very well under load.
   
3. If you some how succeeded in disconnecting the one that goes to the fuel pump, that's a no brainer.

I wouldn't worry about the pump running on, as long as it doesn't stay on.
I use an '89 chip and my pump runs on as well.

What makes you think it rich? fuel, or gray smoke pouring out the tail pipe, explain.

 

the car runs fine under a load,(with the wire disconnected) the pump used to run on for about a min. or so. Vader was trying to help me chase down an impossible code 36. Something about the FP relay and the MAF burnoff switching funtions in the computer itself, (take a look at my post on: MAF burnoff, fuel pump relay mixup?)

The long cranking was happening even befour I unpluged the wire, I was thinking that the cranking and the rich smelling exh. were related.

 

Check the schematic. If the tan/white wire is removed from the auxiliary oil pressure switch and isolated (so it doesn't ground) everythinr will run normally. The only thing that will be different is that the oil pressure switch cannot power the fuel pump. As long as the FP relay is working properly, there will be no problems.

If the engine still runs exessively rich (how are you determining that?) the oxygen sensor is a suspect.

 

The exh. smells rich, to the point of burning my eyes...All the sensors are new, I got the sensor kit from TPIparts.net Is there a way to test the O2 sensor?