I need some help!!!! I have a 1989 Formula 5.7L, the car will start just fine, but if you turn it off and then try to restart it, it will crank, but wont start. If you wait 10 minutes or more, then it will start just fine. Any suggestions?

 

Welcome aboard thirdgen.org.

In order for an engine to run, it needs air, fuel, compression, ignition, and exhaust, in the proper proportions at the proper time.

It isn't likely that having been running and shutting it off would affect air, compression, exhaust, or event timing. So, that leave fuel, ignition, and proper proportions.

Heat is a known affector of electrical stuff. Fuel delivery, ignition, and fuel proportion are all done via electrical stuff - fuel pump, ignition, injectors, and the computer itself. Of those, the most likely to be affected by heat after being shut off is the ignition and injectors.

So, I'd check the coil and the distributor pick-up. But, I wouldn't rule out the fuel pump, either. When it won't start, see if you have spark and/or fuel pressure problems.

 

Well this it the weird thing, it does it when it's cold. I can go out, start the car, turn it off and then try to restart it and it won't unless you wait 10 minutes or so. So heat isn't involved.

 

We're talking about the heat created by the engine, not the ambient outside air temps. There's a tremendous amount of heat created in many different places just from a simple start and run for 1 minute.

Like the ignition module located inside the distributor - if it's old, the grease worn off it's plate, or has an issue from past heat cycles, it can build up electrical resistance really fast (less than 10 seconds even) - resistance is heat in electrical gadgets. Can make it not operate at all until it cools down again (the 10 minutes you experience).

Ignition module can be tested any local parts store chain - start there.

 

Well my mechanic has been working on it for 3 weeks and is getting puzzled (the 1st week was taking the remote start/alarm out). We have changed the module, the distributor, the fuel pressure is fine, plugs and wires are fine. He has been busy this past week and hasn't been able to mess with it much, but I thought I would check on here to see if anyone has had problems like this before or have any thoughts.

 

The word "mechanic" says it all.

 

Thanks for the help camaronewbie!!!!

 

So is there anyone who isn't an arrogant a..hole on here that can help? And when i mean "mechanic" i mean a trusted family friend who knows what he is doing. We have talked to several other people around town here and no one has any ideas. For those who are seriously trying to help me and give me advice.....thank you!!! My guy was also saying there was a loss at the injectors? So something from the ecm to injectors possibly.

 

I would try putting a gage on the rail to see if it holds pressure. If it doesn’t you could have a leaking injector or two. If it starts up after 10-15 min could be a small leak giving you a flooded condition. Just a thought. Hope you figure it out, good luck. Maybe someone will chime in with a little more experience with this.

 

My 89 GTA does exactly the same and has done for a couple of years. Starts very easily when cold but switching off at any time will always mean a wait of maybe 10 minutes before it will restart. Otherwise it will just crank and crank. I've replaced all the usual suspects: no change at all. Fuel pressure is fine but doesn't hold it very well after switching off. I'm almost certain now it's a leaking injector(s). I just live with it (it's not a daily driver) until I can find time to replace the injectors.

 

Hey diffusion and justcruzin, thanks. I was talking to one of my friends last night and he was saying the same thing and that it possible could be a bad seal around the injectors. The guy i bought it off of had it for 3 years and only put around 50 miles on it. So because it sat for so long, it makes me think that it could be the seals.

 

Hey Jwohlf I think your headed in the right direction with the injectors. However the seal or o-ring would make it leak from the rail. Call one of the vendors hear I'm sure they can help and their input is free just the cost of a phone call

 

try a coolant temperature sensor. If it reads wrong it will always think the engine is cold and add too much fuel. It's located right on the front of the motor under the throttle body.

 

We have narrowed it down to probably being the injectors (might have 1 or 2 bad and causing problems). Its not getting gas. Like i said, it starts just fine the very first time, but if you shut it off and try to restart it, it just cranks and doesn't fire. If you wait 7 minutes or so, it will finally fire (stutter a little until it gets enough gas and then runs fine).

 

Well, at the risk of being considered a charter member of the AAH Club, I'll chime in again.

First, you didn't indicate how long you were talking about between starting, shutting it off, and trying to start it again. A reasonable assumption would be you were talking about starting it, running it for some length of time (going to work, the store, etc.), shutting it off, and then not being able to start it again soon after. Now that we have more details, let's try again.

How do you know it's not getting gas? Does it crank & crank, with no hint of trying to start, and then when you pull the plugs they are dry like the engine was shut off after being run? More details, please.

I doubt one or two bad injectors would cause anything like this. It should start on the other 7 or 6 cylinders, unless an injector is shorting out the circuit for all of the injectors. Still not likely, as both banks would have to have this condition at the same time.

Have you put a fuel pressure gauge on it when it is acting up? If you aren't getting fuel pressure, it probably won't start. I had a Bonneville that was hard to start sometimes, fired right up other times. The fuel pump was bad. After replacing the fuel pump, it would always start right up. You may not have a bad fuel pump, though - it could be an electrical problem with the fuel pump power circuit.

 

Yeah it was all a misunderstanding and sorry I didn't provide enough information. I'm not totally mechanically incline, so I didn't know what all to say and I apologize now if I don't explain something correctly. I was and am very frustrated because i just bought the car in march and haven't got to drive it. The previous owner had it for 3 years and had only put around 50 miles on it. It ran rough but i knew it was because of the gas being old. The battery had to be jumped, so when i test drove it I never shut it off to restart it. I drove it home (30min drive) and stopped at a gas station, ran inside and came back out and it wouldn't start. 30 min later it restarted, but because of the bad gas, it wouldn't stay running and once it died, it wouldn't restart. I didn't find out til later once it was at the shop, that you can start it, immediately turn it off and try to restart it and it wont start unless you let it sit 7-10 minutes. So i had the car towed to my friends place (who I know he knows a lot about working on cars, but found out that this was way over his head) and we changed out the module (didn't help). So the next day i drove it to my mechanics shop. He first put some good stablizier in the tank to help the gas and we removed the remote start/alarm that was installed (that didn't help, plus i didnt want the damn thing because i know they cause alot of problems). Also while checking the car over he noticed the distrubuter gears were wore down, so he changed that. Its not throwing any codes. He checked the fuel pressure and its all fine. He has hooked up a diod to the injector and its not lighting up like it should, so that is where he is at. This week he is going to look into and test the injectors more and see why there is a loss at the injectors. At the very begining when you try to restart it, it cranks but doesn't try to turn over. If you wait a couple of minutes, at the very begining it acts like its getting just a small amount of fuel but not enough to turn over, then back to just cranking. If you wait 7 min or more, then it will fire, but its chugging for a few seconds and then runs and idles just fine and normal. I'm sure i'm leaving something out, so if i remember i will sure and post it.

 

I wonder if the fuel pump relay is bad and causing at least part of your issue.

When you turn the key to ON - you should hear the fuel pump whine for 2 seconds - it's priming the system by pumping fuel up to the injectors, so they have fuel to fire with. If the pump doesn't prime, the car will still start, but takes a few minutes of cranking - because there is no fuel at the injectors.

What happens - is that the fuel pump has a back-up circuit through the oil pressure sending unit (OPSU) - when the OPSU senses oil pressure (after a few moments of cranking) it will start to run the fuel pump, and thus it takes a few moments for the OPSU to sense oil pressure, and a few moments for the fuel pump to get fuel up to the injectors so they can fire.

Anyway - might be something to look at - fuel pump relay and/or the connector for it.

 

I do know that when I first start it, I let it prime (and i hear it priming), but what is sad is I don't remember if it does when i try to restart it. I will check that out when I go out to the shop next time.

 

You've received some great input here. One problem for less exprerienced DIYers is putting all this great input into a plan that you can follow. I would start by connecting a spark tester, noid light and fuel pressure gauge to the engine. Start it and run it about as long as it takes for it to not restart. Shut it down and try to start it. When it doesn't start, look at fuel pressure, is it normal(40-45psi)? Look at spark, is it bright? Look at injector pulse. When you verify that these are all okay, pull a plug and look for it to be fuel soaked. If one looks okay, try another. Is suspect you will find a few soaked with fuel.

Check spark on a few wires, at the plug end. Check injector pulse on both banks.

 

Could it be sending fuel to the injectors after the engine shuts off, and flooding it?

 

I knew I was leaving one detail out. While trying to restart it, if someone sprays some fluid in somewhere (see told ya i don't know a whole lot...lol) it will start right up and run normal.

 

Thanks doc. I do know that the fuel pressure is normal and the noid my mechanic connects is not bright (he told me that was a problem and that the noid should glow bright).

 

To me, "crank" and "turn over" are the same thing - the starter makes the crankshaft rotate.

"Start", "run", etc., indicate the combustion process is making the crankshaft rotate without the aid of the starter.

Sounds like the starter will "crank" the engine, but it will not run. Occasionally, a cylinder or two will "fire", but not enough for the engine to "run". Does that sum it up?

I would suggest getting a fuel pressure gauge on there so you know what the fuel pressure is at all times. I suspect it is not coming up to where it should be when you're having these problems. An intermittent relay or intermittent pump would explain it. I would tend toward the relay, since it continues to run when you use starter fluid (the oil pressure would come up sufficiently to power the fuel pump without the timed relay).

 

I didn't notice that you could start it with starting fluid. That throws the leaky injectors theory out the door. Ohm testing the injectors may well show shorted injector coils. If not, you may have a poor ground causing the injector drivers to overheat, or a bad ECM. If the injectors test okay, I would suggest detaching and raising the injector rails so that you can see the injector spray patterns and watch for the spray to be weak.

The question sticking in my mind is whether the car is drivable and continues to run normally if you don't shut it down. Bad injector windings would cause the engine to run poorly once they go low. A poor ground affectimng the quad drivers would eventually cause the engine to stall. There are minor differences between cranking and running. The key differences being the EST is in bypass mode during cranking and injector timing goes high to provide added fuel for starting. If the engine wont start with the failure present, how does it continue to run?

Someone mentioned CTS(coolant temp sensor) it's possible that this sensor could be faulty causing crank fuel to be insufficient at normal engine temps. Generally though I would expect bad CTS data to affect drivability. If you have bad injectors delivering insufficient fuel to start, the cold start injector may be the difference needed to get the engine running. The cold start injector will only operate at low engine temps. It could be that this what is making you wait 10 minutes.

Some things for your mechanic to think about.

 

Well I know he changed out the ECM to see if it made a difference and it didn't, so he put my old one back in. He also had tested the ohms on the injectors and 2 where at 10 the others were either high or low (15 was the highest and 7 was the lowest one). So he thinks the injectors are bad and that is what the problem is, so he is putting new ones in today. I'm crossing my fingers!!!!! (if its not them, then it was an expensive experiment)

 

Injectors should test at 12 ohms. Sounds like you definitely have bad windings. They will heat up and take down the injector pulse. The thing is though that this always causes the engine to run like garbage. Ive never seen an engine that would run well with bad injector windings. That's why I asked if the engine ran okay until you shut it off.

 

It ran a little rough and would idle really low when i first bought it and drove it home. At stop signs and stop lights I would have to put it in neutral so it wouldn't want to die on me. The gas was atleast a year old and so we put fuel stabilizer in it and it idles fine now. I haven't driven it since i took it to the shop. I guess we will know soon enough sometime today once the injectors are swapped out. Trust me i will let you all know when i find out....lol

 

Let us know how those new injectors do.

 

Well it looks like the new injectors fixed the problem!!!!! Now I just can't wait for the weather to get better so I can take it out and drive it. Thank you everybody for your suggestions and help!!!!!!

 

Excellent news and happy motoring!