1985 Corvette will not start (No Spark)
Thread Starter
Heel & Toe
Joined: Apr 2013
Posts: 18
Likes: 0
From: Blue Island Illinois
1985 Corvette will not start (No Spark)
My '85 is in the shop at the moment (don't have the time to work on it myself). It cranks and whatnot, but there's no fuel going to the fuel rail. The mechanic checked the fuel pump, but it works just fine. He bypassed it with some cables and managed to get fuel into the rail, but it is still not starting. As the title states, there is no spark. I gave the mechanic my FSM (one of the nice ones in the blue binder). Any input?
Safety Car
Joined: Aug 2009
Posts: 3,752
Likes: 276
From: Melbourne, Victoria, Australia
My '85 is in the shop at the moment (don't have the time to work on it myself). It cranks and whatnot, but there's no fuel going to the fuel rail. The mechanic checked the fuel pump, but it works just fine. He bypassed it with some cables and managed to get fuel into the rail, but it is still not starting. As the title states, there is no spark. I gave the mechanic my FSM (one of the nice ones in the blue binder). Any input?
If the fuel pump does not run check the fuel pump fuse and that the thick red wire on the fuel pump relay connector has 12 volts from battery, if there is no power the fuseable link may have failed.
Thread Starter
Heel & Toe
Joined: Apr 2013
Posts: 18
Likes: 0
From: Blue Island Illinois
There was no noise coming from the fuel pump when we were starting it. The fuse is fine. I'm assuming the problem is with a wire, but that still doesn't address the issue of when the mechanic powered the fuel pump via cables and then tried starting it. Still didn't start with fuel in the rail
Safety Car
Joined: Aug 2009
Posts: 3,752
Likes: 276
From: Melbourne, Victoria, Australia
The distributor cap has the coil inside, there is a conductor that goes thru the cap that the rotor button touches. That is a common failure point, i have had my 85 cap arc and burn thru and was amazed it would even run.
So check you have power to the distributor, also try disconnecting the tacho wire. From memory there is a tach filter located on the driver side one of the bell housing bolts.
Get your shop manual out and use a multimeter to test the ignition coil and the module.
You have either no power to the distributor (plug on the side of the cap) or the coil and or the distributor module is faulty.
So check you have power to the distributor, also try disconnecting the tacho wire. From memory there is a tach filter located on the driver side one of the bell housing bolts.
Get your shop manual out and use a multimeter to test the ignition coil and the module.
You have either no power to the distributor (plug on the side of the cap) or the coil and or the distributor module is faulty.
Safety Car
Joined: Aug 2009
Posts: 3,752
Likes: 276
From: Melbourne, Victoria, Australia
Another thing to try, the ecm can get itself in a knot trying to adjust things to compensate what it thinks is the problem.
Disconnect the battery (or ecm plug near battery) for ten seconds and reconnect, it may just work after that.
I have come across this in the past, after going thru the usual checks i found disconnecting/ reconnecting the battery solves most issues.
Disconnect the battery (or ecm plug near battery) for ten seconds and reconnect, it may just work after that.
I have come across this in the past, after going thru the usual checks i found disconnecting/ reconnecting the battery solves most issues.
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Melting Slicks
Joined: May 2010
Posts: 2,082
Likes: 3
From: Conowingo Maryland
not trying to be to much of a SA but this is elem stuff. the guy working on it should have the basic checks down in 10 min. these cars are about as easy as can be. Sure there can be broken wire or something like that but the basic are so easy
Thread Starter
Heel & Toe
Joined: Apr 2013
Posts: 18
Likes: 0
From: Blue Island Illinois
Another thing to try, the ecm can get itself in a knot trying to adjust things to compensate what it thinks is the problem.
Disconnect the battery (or ecm plug near battery) for ten seconds and reconnect, it may just work after that.
I have come across this in the past, after going thru the usual checks i found disconnecting/ reconnecting the battery solves most issues.
Disconnect the battery (or ecm plug near battery) for ten seconds and reconnect, it may just work after that.
I have come across this in the past, after going thru the usual checks i found disconnecting/ reconnecting the battery solves most issues.
The mechanic was rather busy so he didn't look that in depth. I would assume he went through the basic checks. I'm going to run the info, recommended by gerardvg, over to him tomorrow. Hopefully he can check into it more.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The ECM will not turn on the fuel pump until it sees reference pulses from the distributor. If the pickup coil or ignition module is bad you won't get those pulses. Check wiring and connectors around the distributor.
Put a timing light on it to see if you have spark. If so, then the distributor is OK and the problems is elsewhere.
Put a timing light on it to see if you have spark. If so, then the distributor is OK and the problems is elsewhere.
Thread Starter
Heel & Toe
Joined: Apr 2013
Posts: 18
Likes: 0
From: Blue Island Illinois
The ECM will not turn on the fuel pump until it sees reference pulses from the distributor. If the pickup coil or ignition module is bad you won't get those pulses. Check wiring and connectors around the distributor.
Put a timing light on it to see if you have spark. If so, then the distributor is OK and the problems is elsewhere.
Put a timing light on it to see if you have spark. If so, then the distributor is OK and the problems is elsewhere.
Burning Brakes
Joined: Jun 2003
Posts: 849
Likes: 1
From: dubuque iowa
i have to agree with one of the above posters here i'm afraid, seems like pretty basic diognosis stuff but why worry about the lack of spark anyhow when the first order of things to address would be fuel... ya ya i know you can jump that but that doesnt fix it and what others are trying to tell you is that they may be one and the same problem or at least associated.
ok now on the fuel pump.. when he jumpers it has fuel but where is he jumpering it? fp relay or right at the tank? that could tell alot right there. also did he try just giving it a good ground without the hot wire ?
as far as no spark others have told you simple verify there is even power to the distributor and go from there.. so far i really havent heard anything verified for further diognosis.
also you say jumpering it he had fuel at the rail, how do you know? how much pressure? did it hold or bleed back down fast? you have to put the effort in to diognos and cure one problem at a time.
ok now on the fuel pump.. when he jumpers it has fuel but where is he jumpering it? fp relay or right at the tank? that could tell alot right there. also did he try just giving it a good ground without the hot wire ?
as far as no spark others have told you simple verify there is even power to the distributor and go from there.. so far i really havent heard anything verified for further diognosis.
also you say jumpering it he had fuel at the rail, how do you know? how much pressure? did it hold or bleed back down fast? you have to put the effort in to diognos and cure one problem at a time.
Last edited by ladystoy69; Jul 24, 2013 at 04:39 PM.