aklim, since you asked, let's start at the beginning of this thread. The OP, a noob to the C4, came here asking about an 89 with a broken ignition and lost key, his words, looking for advice/opinions on the car. I gave mine that the vats system was probably compromised, based upon the broken ignition cylinder (my assumption that it is the ignition cylinder that is broken) and car only barely starting (5seconds). I told the OP that he aught to research the vats system to see if it was something he could or would want to deal with.

You called me out on the vats because the car does try to start and vats normally prevents that. I gave you a sarcastic response (probably wasn't called for, but here we are.) My assessment is based on the broken ignition cylinder AND the fact that the car tries to start with either a missing key or a non vats key. That strongly indicates that some sort of hack was attempted to bypass the vats because yes, if vats was working correctly, under these circumstances the car should not start, yet it tries. Hence the vats is compromised as it tries to start yet won't stay running. There may be, probably are, other issues.

I advised the OP, a noob, to the presence of the vats system and that he aught to look into it. I also thought, without any real knowledge, that this car would be beyond a weekender mechanic and require more than changing spark plugs and wires to make it run and so said that advanced mechanical skills might be required. The OP has since indicated that he has these skills, however electronics and wiring are not everyone's forte, so I wanted him to be aware of the vats.

Neither of us knows what the real issue is with this car, but I do know that vats can be an unsympathetic biatch to get straightened out when it flips out. This is especially true of the early systems (they got better as time went on). . As they age (the first ones are now 35 years old) electronic components in the ecm change value slightly, connectors get dirty changing resistance values presented to the ecm, the key pellet isn't read correctly, again because of dirt/corrosion or just worn parts. So even a stock, untouched system, can have "issues." Some issues are not that much fun to run down and I wanted the OP to be aware.

We obviously disagree on how much, if any, vats is involved with this car's issues. That's ok. But as you know these cars can present myriad electrical gremlins and vats is one of them. So I warned the OP. Is this car "flooding out" as suggested by the current owner? Who knows? Probably ran good when he parked it, right? Says everyone selling a non running car. Or "it's an easy fix." "You can get a bonded title." If everything is so simple, easy and cheap why don't the sellers do it? We all know why, because it ain't true and they are lying. Sorry, got off topic. Yes, vats does get a lot of unnecessary blame, but in this case I think it just might be warranted to at least think about it. YMMV

 

And I doubt it is VATS simply because it started. I have personally owned 2 VATS cars. I cover the pellet and it will not even crank, never mind run for 5 seconds. IDK about it being compromised. I always assumed it either gives the signal to crank or it doesn't. I also don't know how to test the VATS theory out that it kills a running engine. I might suspect the fuel pump circuit since it primes but doesn't seem to keep running, making me think it ran out of fuel after the prime. Maybe the circuit wasn't being energized because it thought there was no ignition pulse? Maybe bad ignition module that fires up for a few seconds? Maybe a fuel pressure check might answer some questions?

2 things. I wasn't trying to "call you out". Merely questioning the logic. 2nd thing, how do you expect me to read words and know there was sarcasm without you stating it first? I don't read minds or I'd definitely be doing things different. From what I see, if you do falsify the signal via a hack, it should crank unless there is something exotic done. I have seen way too many posts that jump on the VATS bandwagon and want to bypass it simply because the car has issues. Failing to get it to work after that, maybe try some diagnostics. THIS and THAT is sposedly how VATS works. IF it is right, even if you put it in run and externally power the starter to crank, there won't be injector pulse so how would that fire for a second? Do you see a REASONABLE way to get the injectors to pulse without a valid signal?

I believe that there are 2 circuits. If enough oil pressure is detected, it will also power the pump. That is a BACKUP circuit. IIRC, the main circuit is from the ECM detecting ignition cycles? I'd look at fuel pressure first before I jump on VATS somehow working out of it's usual pattern of killing the injectors after running a few seconds.

IF the resistance changes, for whatever reason, I would think it goes into what the 2nd article calls a "Tamper" mode and shut down for 4 minutes but again, nothing about running. So even if it went into a "Fail" mode because someone hacked it, that is "tomorrow's problem" and allow the car to run. Kinda why I think it has something to do with fuel being cut off. Fuel, not injector pulse. As far as issues being fun to run down, IMO, it isn't a "some" question. I haven't seen any issues being fun to run down myself but maybe I am funny that way and prefer no issues to any.

Only thing I can think of that causes a flood is too much fuel and not enough spark. Not sure how he is determining that. As far as what the seller or PO says, frankly, I go the other way. I believe the PO or seller is a liar and/or a moron. If I buy a car for more than "junker" prices, IOW one that if it fails, I pull the plates and walk, you can be it gets a PDI from a professional. I have seen someone skim on the transmission filter and change fluid ONLY because they want the buyer to think it is fresh fluid, BY THEIR OWN ADMISSION. My first car purchase introduced me to a car with a lumpy cam. Only thing was the silt in the transmission and a couple of bad cylinders from a PDI.

 

I went ahead and traded for the car. I got it in the shop and have been able to mess with it for a few minutes. When I turn the key on I hear the fuel pump run for a couple seconds. I put a fuel pressure gauge on it. No fuel pressure. I sprayed a little starter fluid in the intake wile cranking it. It fired right up. It will run as long as I am spraying starter fluid in it. The fuel pressure went up to 25 lbs or so wile the car was running. As soon as I quit spraying the starter fluid it dies. Every time I cycle the key I can hear the fuel pump but it won’t raise the fuel pressure gauge. I rented it from orilies so I’m not sure how good it is. Thoughts??

 

If it won't have pressure, 3 things come to mind, Defective pump, bad pulsator (did you replace it and with what?) or leak where the diaphragm is or injectors (unlikely since it runs and didn't hydrolock)

 

I have an update and a couple other questions. I can start the car with starting fluid but it won’t keep running. I have the correct fuel pressure and the plugs are firing when I crank the motor over. My injectors have power on both wires at each injector. I do not have a way to check for pulse. The key that is in the ignition does not have a resistor in it so I assumed that the problem was the vatts but what I have read on other forums is that the vatts will keep the motor from turning over. There are two wires that have been pulled out of the ignition and were stripped and twisted together. I am assuming that those wires are the wires that read the resistance in the key. So all that being said I am wondering if I do indeed have a vatts problem or not. I have no way to know if there has been anything done to the computer to turn off the vatts. I am not concerned about having a security system in this car I would like it bypassed because of what I read about the problems people have had with the vatts. Any help would be greatly appreciated.

 

If engine cranks, it's not vats

 

I would start by pulling the fuel pump assembly and replacing the pump. Inspect for debris in the tank and clean as necessary. Use compressed air to blow out the feed and return lines. Replace the fuel filtered wrll.

 

You really need to know if the injectors are firing. Since it runs on starting fluid and you said you have good fuel pressure, I'd assume they are not. You can try starting it and then pull a plug to see if it's wet with gas. You may also be able to borrow a noid light set from an auto parts store. They are lights that flash when the injector pulses. Also if you have a multi meter that reads duty cycle you can use that or you can just measure voltage across the injector which should drop at least a couple volts when they are firing. One side of the injectors has +12V, the ECM grounds the other side for a few milliseconds to fire the injector.
While it's normally true that VATS will prevent the starter from engaging, sometimes people bypass the VATS starter enable relay when it goes bad. If that was done, it will turn over but not fire the injectors.

 

I rented a tester for the injectors. My injectors are not firing. I have power on both wires but when I plug the node tester in and crank the car it doesn’t flash the light.

 

So now you need to troubleshoot the injector issue. I would guess VATS but it could also be a distributor trigger issue. Do you have the service manual? It will have the steps for troubleshooting.
You can download the '87 version here: https://www.dropbox.com/s/wmizdbj1cj...20SM_.pdf?dl=0
It essentially the same as '89 for this issue.