87 cranks but won't start
Thread Starter
Heel & Toe
Joined: May 2006
Posts: 16
Likes: 0
From: McKinney Tx
87 cranks but won't start
Two weeks ago I purchased an 87 vette. It's high mileage (200k) but ran strong and was a great price. The high mileage almost scared me off until I found out that the car was a one owner daily driver. Besides I wanted a toy to wrench on. So I decided to take the plunge.
I got it home and sometimes it will crank but not start. Other times it fires right up and drives great. After reading some in the forum about similar problems I checked for FUEL, SPARK and AIR. The fuel pump comes on when I turn the key for the 2 seconds and then turns off. So I checked an injector with a noid light and didn’t get any lights (by the way is a GM PFI noid light the correct one? It fit the connector but… what does PFI stand for?) Next, I checked for spark with a tester and didn’t have spark either. I removed the coil, but it looked brand new. Where should I start? ECM? Opti?
If the vette doesn’t start then no amount of trying will bring it to life. I have to wait about 30 min and try again. If I’m lucky then it will fire up.
Before someone posts with the usual FSM comment I have one on the way, but I would like some advice for the holiday weekend.
Thanks in advance!
I got it home and sometimes it will crank but not start. Other times it fires right up and drives great. After reading some in the forum about similar problems I checked for FUEL, SPARK and AIR. The fuel pump comes on when I turn the key for the 2 seconds and then turns off. So I checked an injector with a noid light and didn’t get any lights (by the way is a GM PFI noid light the correct one? It fit the connector but… what does PFI stand for?) Next, I checked for spark with a tester and didn’t have spark either. I removed the coil, but it looked brand new. Where should I start? ECM? Opti?
If the vette doesn’t start then no amount of trying will bring it to life. I have to wait about 30 min and try again. If I’m lucky then it will fire up.
Before someone posts with the usual FSM comment I have one on the way, but I would like some advice for the holiday weekend.
Thanks in advance!
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Fortunately your 87 doesn't have an opti. You can test the spark coil by pulsing 12v across the primary with a .05 -0.1 mfd capacitor across the primary. The secondary will spark if ok. Remove the spark module inside the distributor and have a parts store test it. If ok, then check the pickup coil in the distributor for ohmeter continuity. Check the inj1 and inj2 fuse in the fuse block by the passenger door. The ECM may be defective as it pulses the injector coils. The VATS module may be defective, the part of it that notifies the ECM that the correct ign key pellet is present and to pulse the injectors. Let us know what you find.
Thread Starter
Heel & Toe
Joined: May 2006
Posts: 16
Likes: 0
From: McKinney Tx
Thanks jfb, I'll start the process tomorrow. Not sure how I missed the no opti thing...
I bought the car through a consignment place and someone attempted to break in while it was on the lot. The VATS had to be worked on and the ignition switch was replaced. However it does make me wonder…
I bought the car through a consignment place and someone attempted to break in while it was on the lot. The VATS had to be worked on and the ignition switch was replaced. However it does make me wonder…
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
You are going to need a fuel pressure guage. You hear the pump but don't know what kind of pressure your working with. Pressure should be 36-40 psi. If pressure is good and the injector fuses check o.k. then the noid light will tell you if the harness is o.k. when you attempt to crank. Take the FP fuse out and check for spark first by using a spare spark plug and use each wire getting about 1/2" away from the exhaust manifold while some one cranks on the engine. If there is spark you will see it pulse a blue spark against the manifold. If all 8 spark and the air passage is not blocked (good filter), I would suspect a fuel problem. Anywhere in the fuel system could be the problem but without the fuel pressure guage, it's just a guess at what it is. Could be failing pump, clogged strainer, bad pulsator, leaking fuel line, clogged filter, clogged injector, blown fuses (injector and CSV), and in '87 bad CSV plus more.
Last edited by RRT vette; May 28, 2006 at 07:25 AM.
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Next time you try starting it and have a problem, hold the gas pedal all the way to the floor and see if that makes a difference. All the above advice is good 
BTW, I have several noid lights and the GM PFI (port fuel injection) is the right one, and one I use on my 87. Our 87s are batch fired...meaning each bank of injectors fire (receive their signal) all at once, one side then the other.You should be able to plug your noid light in as an example on #1, crank engine-see light pulsing, #3, crank engine-see light pulsing, etc. You probably know this, and I don't wanna sound like I'm talking down, just wanted to let you know.
BTW, I have several noid lights and the GM PFI (port fuel injection) is the right one, and one I use on my 87. Our 87s are batch fired...meaning each bank of injectors fire (receive their signal) all at once, one side then the other.You should be able to plug your noid light in as an example on #1, crank engine-see light pulsing, #3, crank engine-see light pulsing, etc. You probably know this, and I don't wanna sound like I'm talking down, just wanted to let you know.
Last edited by rick lambert; May 28, 2006 at 08:01 AM.
Thread Starter
Heel & Toe
Joined: May 2006
Posts: 16
Likes: 0
From: McKinney Tx
All good suggestions. Thanks guys. I'll pick up a fuel pressure gauge today. It seems to be basic equip for most troubleshooting.
Rick don’t worry about offending me…I didn’t know much about C4 systems until two weeks ago. Stupid questions will be the norm for a while… I tried pushing the gas in like you suggested but no joy.
I was wondering which system would result in no spark and no injector pulsing, intermittently? VATS? ECM? It does start sometimes, but when it is acting up I have no spark and no injector pulsing.
Rick don’t worry about offending me…I didn’t know much about C4 systems until two weeks ago. Stupid questions will be the norm for a while… I tried pushing the gas in like you suggested but no joy.
I was wondering which system would result in no spark and no injector pulsing, intermittently? VATS? ECM? It does start sometimes, but when it is acting up I have no spark and no injector pulsing.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
VATS will disable the starter. So if it cranks everytime you turn the key then rule out VATS. A faulty connection to or at the ECM will give this problem you stated. When cranking the distrubitor sends refrence pulses to the ECM. From there the ECM will use that information to send pulses to the injectors. I would check connections at the distrubitor too.
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Thread Starter
Heel & Toe
Joined: May 2006
Posts: 16
Likes: 0
From: McKinney Tx
Originally Posted by RRT vette
A faulty connection to or at the ECM will give this problem you stated. When cranking the distrubitor sends refrence pulses to the ECM. From there the ECM will use that information to send pulses to the injectors. I would check connections at the distrubitor too.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
You cannot rule out VATS when your starter motor cranks the engine because the VATS module does TWO things when it detects the correct value resistance pellet in the ignition key. It closes the start enable relay allowing 12v to go to the clutch safety switch (gear selector sw if automatic) and it sends a signal to the ECM to allow pulsing of the injectors. Rare, but it is possible that the VATS module closes the start enable relay but doesn't signal the ECM to pulse the injectors. You might have a poor connection from the VATS relay to the ECM and it takes little effort to unplug the ECM and either plug it back in, or if you have some electrical contact spray, wipe some across the contacts of the ECM and plug the ECM back in. DO NOT use an eraser on the gold plated ECM board fingers!!!!!!!!!!!!!!!!!!!!
Last edited by jfb; May 29, 2006 at 12:31 PM.
Thread Starter
Heel & Toe
Joined: May 2006
Posts: 16
Likes: 0
From: McKinney Tx
Originally Posted by jfb
You cannot rule out VATS when your starter motor cranks the engine because the VATS module does TWO things when it detects the correct value resistance pellet in the ignition key. It closes the start enable relay allowing 12v to go to the clutch safety switch (gear selector sw if automatic) and it sends a signal to the ECM to allow pulsing of the injectors. Rare, but it is possible that the VATS module closes the start enable relay but doesn't signal the ECM to pulse the injectors. You might have a poor connection from the VATS relay to the ECM and it takes little effort to unplug the ECM and either plug it back in, or if you have some electrical contact spray, wipe some across the contacts of the ECM and plug the ECM back in. DO NOT use an eraser on the gold plated ECM board fingers!!!!!!!!!!!!!!!!!!!!
Thread Starter
Heel & Toe
Joined: May 2006
Posts: 16
Likes: 0
From: McKinney Tx
Well I just went out to work on the problem and the car started right up
I don't really don't want to do anything else because I won't know if I have fixed the problem or not! At least when it is not firing I would have a small amount of confidence that I had fixed the problem.
Today is more humid in dallas, I think I will begin tracking if it starts when the humidity is high. Maybe a flaky connection just needs a little moisture in the air. I'll post what I find the next time it doesn't crank. Then again it could just be the phase of the moon. Three straight days of not cranking and then bang, it starts 4 times in a row!
I don't really don't want to do anything else because I won't know if I have fixed the problem or not! At least when it is not firing I would have a small amount of confidence that I had fixed the problem.Today is more humid in dallas, I think I will begin tracking if it starts when the humidity is high. Maybe a flaky connection just needs a little moisture in the air. I'll post what I find the next time it doesn't crank. Then again it could just be the phase of the moon. Three straight days of not cranking and then bang, it starts 4 times in a row!
Thread Starter
Heel & Toe
Joined: May 2006
Posts: 16
Likes: 0
From: McKinney Tx
I switched gears and changed the turn signal flasher, which meant that I had to remove the ECM.
I cleaned the pins and connector with some electrical cleaner while it was removed.
So far the car still wants to start. I'll post again if/when it decides to act up.
Thanks for the advice everyone
I cleaned the pins and connector with some electrical cleaner while it was removed.
So far the car still wants to start. I'll post again if/when it decides to act up.
Thanks for the advice everyone
Safety Car
Joined: May 2006
Posts: 4,290
Likes: 140
From: Salem NH
Originally Posted by Dr. Funkenstein
Two weeks ago I purchased an 87 vette. It's high mileage (200k) but ran strong and was a great price. The high mileage almost scared me off until I found out that the car was a one owner daily driver. Besides I wanted a toy to wrench on. So I decided to take the plunge.
I got it home and sometimes it will crank but not start. Other times it fires right up and drives great. After reading some in the forum about similar problems I checked for FUEL, SPARK and AIR. The fuel pump comes on when I turn the key for the 2 seconds and then turns off. So I checked an injector with a noid light and didn’t get any lights (by the way is a GM PFI noid light the correct one? It fit the connector but… what does PFI stand for?) Next, I checked for spark with a tester and didn’t have spark either. I removed the coil, but it looked brand new. Where should I start? ECM? Opti?
If the vette doesn’t start then no amount of trying will bring it to life. I have to wait about 30 min and try again. If I’m lucky then it will fire up.
Before someone posts with the usual FSM comment I have one on the way, but I would like some advice for the holiday weekend.
Thanks in advance!
I got it home and sometimes it will crank but not start. Other times it fires right up and drives great. After reading some in the forum about similar problems I checked for FUEL, SPARK and AIR. The fuel pump comes on when I turn the key for the 2 seconds and then turns off. So I checked an injector with a noid light and didn’t get any lights (by the way is a GM PFI noid light the correct one? It fit the connector but… what does PFI stand for?) Next, I checked for spark with a tester and didn’t have spark either. I removed the coil, but it looked brand new. Where should I start? ECM? Opti?
If the vette doesn’t start then no amount of trying will bring it to life. I have to wait about 30 min and try again. If I’m lucky then it will fire up.
Before someone posts with the usual FSM comment I have one on the way, but I would like some advice for the holiday weekend.
Thanks in advance!
You need a scanner
If you get no DRP's than the ecm won't fire the injectors. Best tool really is the scanner. If while cranking you see no DRP, no RPM fluxuation you've isolated it to an ignition problem. Could be the module, pickup, etc.
-- Joe
Thread Starter
Heel & Toe
Joined: May 2006
Posts: 16
Likes: 0
From: McKinney Tx
Originally Posted by anesthes
You need a scanner
-- Joe
-- Joe
Thanks Joe. I got the Helms in Friday and quickly came to the same conclusion. Every troubleshooting diagram that has to do with the distributor or fuel injectors or ECM gets to a point and says to connect a scanner. Good to know that someone else thought the same way! So I was thinking about the ALDL OBD1 cable found here:
http://www.aldlcable.com/
Has anyone had a good or bad experience with this?
I have an old desktop laying around with a serial port so I was going to check the system with serial first, but my laptop only has USB (this seems to be a typical problem on the forum).
Does anyone have any good experiences with USB to serial adapters working with the ALDL cable?
Safety Car
Joined: May 2006
Posts: 4,290
Likes: 140
From: Salem NH
Originally Posted by Dr. Funkenstein
Thanks Joe. I got the Helms in Friday and quickly came to the same conclusion. Every troubleshooting diagram that has to do with the distributor or fuel injectors or ECM gets to a point and says to connect a scanner. Good to know that someone else thought the same way! So I was thinking about the ALDL OBD1 cable found here:
http://www.aldlcable.com/
Has anyone had a good or bad experience with this?
I have an old desktop laying around with a serial port so I was going to check the system with serial first, but my laptop only has USB (this seems to be a typical problem on the forum).
Does anyone have any good experiences with USB to serial adapters working with the ALDL cable?
I've made a few simple aldl cables. THe last one I used I got on ebay from poland. Was like 35 bux.. I use a keyspan usb to serial adapter on my new laptop, as it's USB only.. I've used datamaster, and tunerpro.
Both work great.
-- Joe
Thread Starter
Heel & Toe
Joined: May 2006
Posts: 16
Likes: 0
From: McKinney Tx
Thanks Joe, I'll look into it. I found several schematics online for the cables and I'm handy with a soldering iron (EE by profession), but I don't want to end up in the situation of debuggin my new cable and by ECM at the same time. I'm still not sure if the ECM is behaving!
Instructor
Joined: Jun 2006
Posts: 194
Likes: 0
From: Hartselle Al
I’m not reading all this, so I’m just going to ask. Does the car have spark from the distributor? If not, have you tested the ignition module?
Since you’re new, I think its under the cap for that model.
Since you’re new, I think its under the cap for that model.
Thread Starter
Heel & Toe
Joined: May 2006
Posts: 16
Likes: 0
From: McKinney Tx
That's the part that has me puzzled... when it is acting up I don't have spark or injector signal. I'm still a bit foggy on if the ICM would interupt the signal from the pickup coil. Then again I'm a bit foggy on the whole system still. I'm still drinking from a firehose. I know that the O'Reilly in town would test the ICM for me, but with it being an intermittant would it be worth the trouble?