Miltish

My first post so excuse me if I muck this up.
I've got an 86 that is having some cold idle issues. Trouble staying running when cold. Starts quickly idles about 1100 then shuts off. As though I may have a fuel pressure or fuel supply issue. In-tank pump, new in-line filter, new injectors. In trying to pull the codes, my service manual indicates that the service engine soon light should come on when the key is turned on and go out when cranking. Mine comes on for 1-2 seconds when the key is first turned on and then goes out. Is this normal or should the light remain on? I'm sure I'll have more ?'s as I go fwd but gotta start somewhere. Thanks

Tod Stiles

The SES light should be steady illuminated when the key is in the run position with the engine not running. It should go out with the engine running unless a code is set.

Miltish

That's what I thought. mine comes on for same amount of time it takes to pressurize the fuel line. IE: about 2 secs and then goes off. Any ideas?

Tod Stiles

If you have the FSM you're going to want to look at chart A-1 and A-2 in section six. It all revolves around shorts and opens in the ECM circuit/solenoids and ultimately a ECM problem.

But before going there I would check the usual suspects blown fuse or other obvious problem. I would check to see that the battery is good and is well grounded to the body and engine. The ground are often a problem. make sure the charging system is good. Sounds like it runs for long enough that you can put a voltmeter on the battery and see if it's charging.

Could all be part of the same problem or the running problem could be a separate issue but you got to get the ECM working right first.

Miltish

Thanks Todd!
I'll check that out and be back.

billschroeder5842

2 seconds illumination is pretty normal after start-as long as it goes off. Don't chase this rabbit as you wont get to your problem.

When you say, the car shuts off am I to assume that it dies as in "restart required?" What happens if you "feather" the gas pedal after start? Does it die anyway or can you keep it going?

Miltish

yes, I can keep it running or if it dies I can restart and feather, eventually the car will warm up and run.

I should add some background, this car has had the cats removed the egr valve removed and covered with a plate and the air system taken off. a new ECM installed a while back and a hypertec chip installed.

Tod Stiles

Except that's not the symptom. Unless I'm misunderstanding the OP, the ECU is failing at powerup. I'd be interested to know how you would proceed. If I misunderstood the OP, my apologies.

Tod Stiles

Do you know if any of that was done to try and cure the running problem? Depending how the EGR was removed, that could give you a code.

Miltish

I don't know the entire answer. I believe the cats came off because they were 20 + years old and the car was registered in AZ and didn't need inspection. The car has had a history of surging at idle but don't know if that lead to the EGR and AIR removal. trying to find codes is what lead me to look at the service engine light. Honestly were it not for that, I probably wouldn't have known, you turn the key the pump starts and the light goes on when the pump stops the light goes out. You turn it to crank and the car fires up. it runs smooth for a couple seconds then cuts out. it almost seems like it is burning the fuel already in the rail but no more is being pumped in to refill it.

Tod Stiles

Sounds as though the FP is starting OK. (runs for a couple of seconds with key in "run"). Can you put a pressure gauge on the fuel rail while it runs to see if the pressure drops?

RF1

Any codes stored in the ecm?

Miltish

sorry, been out of pocket for a few days. Here is what I know. Fuel pressure goes to 40 with key on and immediately starts dropping, maybe takes 60 seconds to go to zero. SES light is on while pump is on. Goes out 2 secs later. Car fires right up and settles down to about 800 rpm with 36-38psi fuel pressure. When I try to open the throttle. Pressure climbs to 40ish psi momentarily and car hesitates. if i hold the throttle cracked, the car dies, if i release it, I get a slight increase in rpm as it settles back to idle. ECM won't go into the diagnostic mode and so I can't pull codes. when I ground the AB terminals the cooling fan starts and the Over drive light comes on but no SES light and no code 12 flash. to try and fix the fuel pressure issue, I have changed the pump, the regulator, the filter, pulled the fuel rail with the injectors including the cold start injectors and pressurized the system per the FSM. no leaking injectors, I have looked at the lines and the fittings no apparent leaks, and done the test where you pinch the return, the pressure and then both lines. Nothing keeps the pressure from falling. Got a new Delco pump and a new FP gauge coming tomorrow. If that doesn't work I'm going to pull all my new FIC injectors out and send 'em back with my cold start injector for a test. I'm treating this like 2 separate problems. 1 system won't hold pressure. 2 car won't accelerate from idle. OK three problems. MY ECM won't act right. i.e.: no steady SES light pre start, and won't go into diagnostic mode. Any ideas are WELCOME!

Tod Stiles

I would get the ECM figured out first, you don't know what's going on without it working correctly. I wouldn't worry too much about losing pressure with the engine off for now. Although it's defiantly desirable for it not to leak down so fast, if everything else is OK that won't affect the running much. Seen this many times.

I'd start with the typical culprits, grounds and so forth and then go to the non-scan diagnostic check in the FSM to find out whats going on with the ecm. Page 6E3-A-8 in my 86 book.

Miltish

Thanks, I'll check it out.