1989 corvette won't start
Thread Starter
Navigator
Joined: Oct 2012
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1989 corvette won't start
Ok so this isn't even my car unfortunately I am not a corvette owner. 
I am trying to help my friend though and am posting this for him. It originally start about a year ago. After the car was drove for about an hour it would just shut off after it set for about 5 minutes it would start back up and run fine again. It went on like that for about a month. Then one day it wouldn't start back. Before I started helping him he already put a new fuel pump and filter a new ecm a new maf and I think that's about it. It will run on ether, and if the car sits for about 10 minutes it will catch and almost start then just die. It has good fuel pressure at the rail, and the noid light blinked on each injector. Also it is not throwing any codes. So anybody got any ideas? What should we test next or look for? Thank y'all for your time and help.
-Matt
I am trying to help my friend though and am posting this for him. It originally start about a year ago. After the car was drove for about an hour it would just shut off after it set for about 5 minutes it would start back up and run fine again. It went on like that for about a month. Then one day it wouldn't start back. Before I started helping him he already put a new fuel pump and filter a new ecm a new maf and I think that's about it. It will run on ether, and if the car sits for about 10 minutes it will catch and almost start then just die. It has good fuel pressure at the rail, and the noid light blinked on each injector. Also it is not throwing any codes. So anybody got any ideas? What should we test next or look for? Thank y'all for your time and help.
-Matt
Race Director
Joined: Apr 2002
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From: Anaheim CA
Check the ignition module in the distributor. It should have THERMAL grease under it, NOT dielectric grease. They get REALLY hot and fail. Come to think of it, they sometimes just fail, period. Take it apart, clean everything up and put new THERMAL grease under the module. If you buy a new module it should come with the correct grease.
A friend of mine had a similar problem (ran fine cold, died when hot) and it turned out to be a bad connection at the terminals of the ignition coil (in the cap of the distributor). The connector pins are crimped onto the wires from the coil and one of them was loose. He soldered all the terminals and hasn't had a problem since.
A friend of mine had a similar problem (ran fine cold, died when hot) and it turned out to be a bad connection at the terminals of the ignition coil (in the cap of the distributor). The connector pins are crimped onto the wires from the coil and one of them was loose. He soldered all the terminals and hasn't had a problem since.
Burning Brakes
Joined: May 2011
Posts: 838
Likes: 2
From: Louisville Ky
it's always the same routines to locate the root cause: either spark, or air/fuel delivered in the proper ratio. no start can be no fuel, or rich fuel. if in jectors blink, probably ecm is firing them ok.
check for a strong blue spark first. an intermittent spark is No spark.
if TPI engines have one inj leaking, it can foul several plugs during start. also pull vac line from fuel pressure regulator to see if fuel comes out, indicating a leak.
if you suspect it is over-rich, try the throttle open while cranking. just looking for clues at this point.
check for a strong blue spark first. an intermittent spark is No spark.
if TPI engines have one inj leaking, it can foul several plugs during start. also pull vac line from fuel pressure regulator to see if fuel comes out, indicating a leak.
if you suspect it is over-rich, try the throttle open while cranking. just looking for clues at this point.
Thread Starter
Navigator
Joined: Oct 2012
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He said it has a new ignition module already, but I'll check and see what kind of grease he used if any. It has a strong blue spark we already checked for that. Ill check the fuel pressure regulator this evening. We've tried starting it with the throttle in every position possible the only way it gets close to starting is leave it sit for ten minutes don't touch the gas and turn it over it'll start for just a second and die.
Race Director
Joined: Dec 2000
Posts: 17,551
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From: El Paso Texas
You need to run the diagnostics during a no-start event. What you're describing is indicative of an ignition system problem. Any parts store can test the module, and as mentioned above, ensure the base is clean and has a THIN coating of thermal grease under it.
When it won't start, tell us exactly how many psi of fuel pressure you have, and if you have spark (use a tester).
When it won't start, tell us exactly how many psi of fuel pressure you have, and if you have spark (use a tester).
Thread Starter
Navigator
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Well the car will not start at all right now so everything is a no start event right? And it had 45 Pei of fuel pressure and as soon as I get off we can take the ignition module to get tested. What would I use to test spark besides grounding it and watching the spark?
Race Director
Joined: Dec 2000
Posts: 17,551
Likes: 26
From: El Paso Texas
You can buy an inline spark tester at any parts store. They're under $10 at Harbor Freight.
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Race Director
Joined: Dec 2000
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From: El Paso Texas
Yes.
When you turn the key on (without cranking), do you get the 2 second fuel pump prime and full fuel pressure? If so, how long does it hold? What I'm looking for is a failed fuel pump relay, and weak oil pressure switch (secondary path). If the relay is failed and it isn't developing sufficient oil pressure during cranking to activate the secondary path, it won't start.....but spraying ether in causes it to run momentarily and build enough oil pressure to keep the secondary path closed, and thus the fuel pump energized.
You mentioned you get injector pulses....is this when cranking during a no-start event? I want to see if the TPS is shorted and you're in "clear flood" mode.
When you turn the key on (without cranking), do you get the 2 second fuel pump prime and full fuel pressure? If so, how long does it hold? What I'm looking for is a failed fuel pump relay, and weak oil pressure switch (secondary path). If the relay is failed and it isn't developing sufficient oil pressure during cranking to activate the secondary path, it won't start.....but spraying ether in causes it to run momentarily and build enough oil pressure to keep the secondary path closed, and thus the fuel pump energized.
You mentioned you get injector pulses....is this when cranking during a no-start event? I want to see if the TPS is shorted and you're in "clear flood" mode.
Thread Starter
Navigator
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We get code 12 over and over again. It holds like 45 psi of fuel pressure and according to the dash the oil pressure is over 4. We did find out the fuel pressure regulator is bad and we will replace it tomorrow. Could that cause all these symptoms?
Team Owner
Joined: Jan 2003
Posts: 20,314
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From: Summerland B.C. Canada
89 was known for failing injectors. Ohm test each one and post the #'s.
Quick test to see if they are doing any real injection, is to hook up your fuel pressure gauge, prime the rail, remove fuel pump fuse and crank the engine.
If they are injecting, your fuel pressure will pulse it's way down to no pressure.
Quick test to see if they are doing any real injection, is to hook up your fuel pressure gauge, prime the rail, remove fuel pump fuse and crank the engine.
If they are injecting, your fuel pressure will pulse it's way down to no pressure.
Burning Brakes
Joined: May 2011
Posts: 838
Likes: 2
From: Louisville Ky
if vac line is leaking, you may have the problem right there.
if you have a blinking node light it means ecm is operating injectors. but one of the several sensors tell it what the A/F ratio should be. if you unplug one, it will go to default, either to another sensor or to ecm memory.
try unplugging TPS. if no reaction, connect it, and unplug MAF. not sure if it should be using the 02 sensor right after shutoff, but if it is this will force the ecm to use another sensor, if I understand it correctly.
Race Director
Joined: Dec 2000
Posts: 17,551
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From: El Paso Texas
89 was known for failing injectors. Ohm test each one and post the #'s.
Quick test to see if they are doing any real injection, is to hook up your fuel pressure gauge, prime the rail, remove fuel pump fuse and crank the engine.
If they are injecting, your fuel pressure will pulse it's way down to no pressure.
Quick test to see if they are doing any real injection, is to hook up your fuel pressure gauge, prime the rail, remove fuel pump fuse and crank the engine.
If they are injecting, your fuel pressure will pulse it's way down to no pressure.
Now we're getting somewhere.
Thread Starter
Navigator
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Ill definitely try the ohm test and see if hold pressure with the fuse out. I pulled the vacuum line of the fpr and it smelled like pure gas indicateing the diaphragm is tore right? Ill try unplugging different sensors also and see if it changes anything. Thanks for all the help so far.
Team Owner
Joined: Jan 2003
Posts: 20,314
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From: Summerland B.C. Canada
If not, your fuel pressure gauge should notice a drop after rail prime and you may see gas exit reg nipple.
Thread Starter
Navigator
Joined: Oct 2012
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Ok finally got a chance to mess with it today. It will not hold fuel pressure after it primes. If we clamp off the return line it will hold pressure. So that means the fpr is bad right? That don't make sense though because the fore is brand new.any suggestions anything to try?
Safety Car
Joined: Jan 2004
Posts: 3,556
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Will it start up with line ( until it fires ) clamped to hold the pressure ?
