Cranks but No Start

[green zr 1]

In the last month, ZR-1 has started and on warmup when the idle comes down to 700 RPM, it stalls. Got sys on gauges, battery light, no ses light. Replaced battery, cleaned grounds to frame under the battery, Engine cranks fine, battery light still on, no ses light. GM service manual says I should have ses light. Do not hear fuel pumps and did not get spark on last attempt. Air conditioning comes on sporadically during cranking. It has started sporadically and run fine a couple of times with no symptoms during these problems. Any help is appreciated. Thanks, Shannon Walton 1990 ZR-1#1066

[jonszr1]

I' m noyt totally sure. but take a look at the Vatts(security ) when you turn the key on what does the security light on the inst. panel do? the lack of the fuel pumps working steers me that way. I don't know if this helps .maybe someone else can chime in .If you don't solve it sun pm me and I'll give you a ph number to call on Mon . I know he could figure it out . Good luck.

[GrayZ]

check out your map hose..located on the rear of the engine...in the middle...my car had similiar symptoms...and we found out that the hose was collapsing...it was too soft and pliable...after replacing...many of my problems...vanished..like a ghost..

[tomtom72]

Man that's a lot of wierdness going on all at once! You did check the grounds at the back of the motor? What about the power distribution block just aft of the battery?.....The hood latch drain(?) empties out on to it, great idea GM! Mine was quite corroded, alot of surface stuff, I guess I got to it in time.

Seems to me something is not okay with wiring....too many sysmptom happening all at once, from seemingly unrelated sources. I mean what's the HVAC system doing coming on line when it's not called by you pushing one of the buttons? You checked the four ECM plugs...they are seated well?

Quickie test on the fuel pumps, put a gauge on the schrader valve at the front of the right rail & crank....should be 48 - 55 psi (?)...check the FSM for the figures...if it starts up let it run with the gauge on & see where the numbers settle out...again see FSM for the #'s. If it goes south quickly then do the diagnostic chart on the fuel pumps to find the problem.

Intermittant no spark? You could do an ohm test from one plug wire end thru the coil and out to the other plug wire end.....I think 25K ohms is good but I'm not positive on that figure. The control box, DIS module, needs a special tool to scan it, so I can't say anything except look in the FSM & maybe there is another way to do diagnostics on that system.

There is a thread on the VATTS system here, it's a great thread too! Go look at it & see if you have a commonality with it. I'm no good at VATTS, so I don't want to say something to point you in the wrong direction.

Do you have a scan tool? You could hook it up & do a KOEO scan just to see if there are any history codes that would throw some light on your situation. You can even do the jumper wire thing on the ALDL connector....again I'm ham fisted, I have "sausage fingers" so I use a scan tool or Gordon's jumper plugs on my car!

Sorry I can't point to any one thing for ya!

Tom

Oh yes....the map hose....I forgot!!!!

[tccrab]

Originally Posted by green zr 1

In the last month, ZR-1 has started and on warmup when the idle comes down to 700 RPM, it stalls. Got sys on gauges, battery light, no ses light. Replaced battery, cleaned grounds to frame under the battery, Engine cranks fine, battery light still on, no ses light. GM service manual says I should have ses light. Do not hear fuel pumps and did not get spark on last attempt. Air conditioning comes on sporadically during cranking. It has started sporadically and run fine a couple of times with no symptoms during these problems. Any help is appreciated. Thanks, Shannon Walton 1990 ZR-1#1066

I'm with TomTom, it sounds like you've got multiple perhaps unrelated problems.
First thing to check is the MAP sensor hose and the two hose vacuum connector under the throttle body on the drivers side. It's a goofy looking rubber thingy that connects the Metal PCV hose to the plenum and also a hose that goes up to the vacuum pump. Either one of these will cause rough idle and stalling.
The air conditioner going on all by itself to me indicates a problem with the battery or battery connections. When you remove the battery cable and put it back on the air conditioner always comes on, it's some kind of crazy default. If yours is going on all by itself this would seem to indicate that the power goes off and comes back on quickly. Do any of the dash lights dim just prior to the AC coming on?
If the battery light stays on this would indicate a problem with the alternator or charging system. This is probably related to the AC coming on, but can't for the life of me imagine how...
The no fuel, no spark sounds like VATS, but could also be related to a problem with the ECM. Try locking/unlocking the drivers door with the key a few times and also try one of the spare keys in the ignition. You may have a bad resistor in the key and/or corroded connections.

Electrical problems can be extremely difficult to diagnose, especially if the symptoms appear unrelated.
I'd call one or more of the ZR1 specialists, Hiabeck, Corey, etc., describe your symptoms, maybe they've seen something like this before.

Good luck!

TomC
'90ZR1 #792

[green zr 1]

Thanks, Guys. A little more info is needed. The battery was replaced last week. All the grounds were cleaned to the frame and seemed o.k. to the back of the block. Until this no start condition, everything has functioned normally. Battery light has stayed on, car still has the original alternator. Can the car start and/or run if the alternator bad? I also still get no ses light I have not unhooked the ecm connectors yet, and I wonder if that may be helpful. The car is stored in a very cold climate, and I have had corrosion on the ground straps that I just recently cleaned. Please throw any ideas my way. Shannon Walton ZR-1 1990 #1066

[jonszr1]

Did you ck the little magnet thingy on your ignition key? I got this funny feeling.......

[tomtom72]

I just read TomC's post & I have to write this before I forget it! Old age stinks!

I believe our ignition systems have a fuseble link. It's one of the wires on the terminal block that I talked about in my last post, actually I think that that block has 3 or 4 fuseble links connected to it. Also that you say "cold & damp" I think corrosion on all the connectors' pins, grounds and any exposed lugs used for the electrical system....I know, not a pleasant thought. The going on & off of the A/C is what makes me suspect voltage is being interrupted somewhere, some how.

Oh, yes a car with a way good battery can start & run without a working alternator....not for long but it will start & run.


Tom

[tccrab]

Originally Posted by green zr 1

Thanks, Guys. A little more info is needed. The battery was replaced last week. All the grounds were cleaned to the frame and seemed o.k. to the back of the block. Until this no start condition, everything has functioned normally. Battery light has stayed on, car still has the original alternator. Can the car start and/or run if the alternator bad? I also still get no ses light I have not unhooked the ecm connectors yet, and I wonder if that may be helpful. The car is stored in a very cold climate, and I have had corrosion on the ground straps that I just recently cleaned. Please throw any ideas my way. Shannon Walton ZR-1 1990 #1066

Shannon:

Relaced the battery?
What battery did you use?
Some batteries have posts on the top as well as the posts on the sides. If the post on the top contacts the ECM support all kinds of interesting things can (and do) happen.
You should unhook the negative battery cable if you intend to unplug the ECM. I doubt that the contacts in the ECM have corrosion, the plugs are sealed pretty well. I'd check the Fusable links as per TomTom's suggestion.

Is your Security Light on all the time or does it flash when you try to start the car?
If the Security light is steady, then VATS is what's causing your NoStart.

What part of the world do you live? If you're reasonably close to one of us active members, most any of us will drop by to take a look and offer advice. Sometimes a different set of eyes can spot a problem easier.
It's why it's called "The Brotherhood of the Beast".
I'm in the Sacramento CA area. Are you close?

TomC
'90 ZR1 #792

[green zr 1]

Tom, I just installed the correct AC Delco replacement battery and it has side terminals. The previous battery cracked and leaked a little acid on the frame and caused some corrosion which I have meticulously cleaned. In between these problems, the car has started and run perfect a couple of times, but the problem has reoccurred and is now a no start. It has also not been driven on a wet road in six years. All of the positive wire connections to the terminal block have been cleaned thoroughly, but I have not checked the fusable links. I was under the impression based on what I read in the service manual that if I did not have the ses light I could have a bad power connection to the ecm. The car is currently in my garage in Calais, Maine, one mile from the Canadian border, and I am on vacation in Northern Virginia this week. The security light flashes, does not stay on steady, so I have just assumed that it was not the VATS system but nothing would surprise me at this point. I am trying to resolve these problems as soon as possible, so the car can be moved to a much warmer location in the south before there is six feet of snow in front of my garage door. Please keep the ideas coming. Also, the map hose is clear and still connected at both ends and seems to be fine. Thanks. Shannon Walton ZR-1 1990 #1066