84 corvette crossfile injection issue
Thread Starter
Heel & Toe
Joined: Jun 2010
Posts: 21
Likes: 0
From: Navarre Florida
84 corvette crossfile injection issue
Hello,
I have a 1984 Corvette with the factory crossfire injection system and I am having some issues. The problem I am having started after I let the car set up for about 2 weeks, I drove it to work one morning and the car ran absolutely fine but when I got ready to leave work that afternoon, the fuel system was not delivering any fuel into the intake. I thought it was perhaps a fuel pump issue so I replaced it and had the same results....I decided to leave the car in the parking lot and come back to it later in the week after work and when I cam back to it, the car fired up as if it had never had a problem so I drove it home. I tested cranking it up at the house over the last few weeks and ran fine up until a few weeks ago now.
After it started acting up again, I tried resetting the car by removing the battery and I still had nothing...I ended up replacing the ECM module and that did not even fix the problem.
So far, I have found that the whole ignition seems to be down because I could not even get the engine to run with starting fluid.
Has anyone else had this problem before out of their Crossfire injection?
Thanks for your time, I really appreciate it!
Jareth
I have a 1984 Corvette with the factory crossfire injection system and I am having some issues. The problem I am having started after I let the car set up for about 2 weeks, I drove it to work one morning and the car ran absolutely fine but when I got ready to leave work that afternoon, the fuel system was not delivering any fuel into the intake. I thought it was perhaps a fuel pump issue so I replaced it and had the same results....I decided to leave the car in the parking lot and come back to it later in the week after work and when I cam back to it, the car fired up as if it had never had a problem so I drove it home. I tested cranking it up at the house over the last few weeks and ran fine up until a few weeks ago now.
After it started acting up again, I tried resetting the car by removing the battery and I still had nothing...I ended up replacing the ECM module and that did not even fix the problem.
So far, I have found that the whole ignition seems to be down because I could not even get the engine to run with starting fluid.
Has anyone else had this problem before out of their Crossfire injection?
Thanks for your time, I really appreciate it!
Jareth
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
No, I have never had that problem out of my Crossfire Injection before.
Sounds like you've wasted a lot of money throwing a lot of parts at it...for nothing so far. Shall we start down a diagnostic path now? If you're interested...
Start by checking for spark, rather than guessing. Do you know how to test for spark?
Sounds like you've wasted a lot of money throwing a lot of parts at it...for nothing so far. Shall we start down a diagnostic path now? If you're interested...
Start by checking for spark, rather than guessing. Do you know how to test for spark?
Race Director
Joined: Dec 2000
Posts: 17,551
Likes: 26
From: El Paso Texas
You likely have a failed ignition module. Remove the module and have it tested. Any parts store can do this. But above all, troubleshoot and stop guessing / throwing parts at it.
Before spending one more penny on it, I want to know how many lbs of fuel pressure you have at key on (should be 9-13, but they won't run correctly below 10). The fact that you replaced the pump is immaterial.
Use a spark tester also and test for spark. Given that it won't fire on starting fluid, your no-start is likely igntion/emissions related.
Post results.
Before spending one more penny on it, I want to know how many lbs of fuel pressure you have at key on (should be 9-13, but they won't run correctly below 10). The fact that you replaced the pump is immaterial.
Use a spark tester also and test for spark. Given that it won't fire on starting fluid, your no-start is likely igntion/emissions related.
Post results.
Race Director
Joined: Dec 2000
Posts: 17,551
Likes: 26
From: El Paso Texas
No, I have never had that problem out of my Crossfire Injection before.
Sounds like you've wasted a lot of money throwing a lot of parts at it...for nothing so far. Shall we start down a diagnostic path now? If you're interested...
Start by checking for spark, rather than guessing. Do you know how to test for spark?
Sounds like you've wasted a lot of money throwing a lot of parts at it...for nothing so far. Shall we start down a diagnostic path now? If you're interested...
Start by checking for spark, rather than guessing. Do you know how to test for spark?
Beat me to it by a minute. 
Thread Starter
Heel & Toe
Joined: Jun 2010
Posts: 21
Likes: 0
From: Navarre Florida
You likely have a failed ignition module. Remove the module and have it tested. Any parts store can do this. But above all, troubleshoot and stop guessing / throwing parts at it.
Before spending one more penny on it, I want to know how many lbs of fuel pressure you have at key on (should be 9-13, but they won't run correctly below 10). The fact that you replaced the pump is immaterial.
Use a spark tester also and test for spark. Given that it won't fire on starting fluid, your no-start is likely igntion/emissions related.
Post results.
Before spending one more penny on it, I want to know how many lbs of fuel pressure you have at key on (should be 9-13, but they won't run correctly below 10). The fact that you replaced the pump is immaterial.
Use a spark tester also and test for spark. Given that it won't fire on starting fluid, your no-start is likely igntion/emissions related.
Post results.
I will check for spark for sure and see if I am getting anything. I do have good fuel pressure now since I replaced the fuel pump, the pressure was low with the old pump which is why I changed it out.
I will get back with you after I see if I have spark.
Really appreciate your help!
Thread Starter
Heel & Toe
Joined: Jun 2010
Posts: 21
Likes: 0
From: Navarre Florida
No, I have never had that problem out of my Crossfire Injection before.
Sounds like you've wasted a lot of money throwing a lot of parts at it...for nothing so far. Shall we start down a diagnostic path now? If you're interested...
Start by checking for spark, rather than guessing. Do you know how to test for spark?
Sounds like you've wasted a lot of money throwing a lot of parts at it...for nothing so far. Shall we start down a diagnostic path now? If you're interested...
Start by checking for spark, rather than guessing. Do you know how to test for spark?
Luckily I have not wasted much money at all, the ECM was given to me.
I hate playing the guessing game on things, after all, I am an electronics tech but I have been a bit lazy on this problem.
I will check for spark and get back with you.
Thanks again,
Jareth
Heel & Toe
Joined: Oct 2012
Posts: 22
Likes: 0
What about the oil pressure switch? It is in the valley right behind the intake. My understanding is it is tied into the fuel pump relay and will not switch the pump on unless there is oil pressure. During a no start i would try bypassing the switch.
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Thread Starter
Heel & Toe
Joined: Jun 2010
Posts: 21
Likes: 0
From: Navarre Florida
Thread Starter
Heel & Toe
Joined: Jun 2010
Posts: 21
Likes: 0
From: Navarre Florida
Le Mans Master
Joined: May 2006
Posts: 9,226
Likes: 9
From: Irvine Ca
Your injectors 'should' be firing with 11psi. Good for you for checking that possibility
Thread Starter
Heel & Toe
Joined: Jun 2010
Posts: 21
Likes: 0
From: Navarre Florida
Thanks,
Jareth
Race Director
Joined: Dec 2000
Posts: 17,551
Likes: 26
From: El Paso Texas
The oil pressure switch is wired in PARALLEL, NOT SERIES with the fuel pump circuit. It is there as a backup in case the fuel pump relay fails. It will supply voltage in the event of relay failure to the fuel pump circuit once the engine reaches approx. 4 psi during cranking so the engine will still start if the relay quits.
If the relay is functional, the engine will start and run with ZERO oil pressure....well, until it seizes anyway. The oil pressure switch is NOT a failsafe to "save" the engine in the event of a drop in oil pressure, nor is it required to start the car if the relay is functioning. Bypassing it is a complete waste of time.
See Factory Service Manual for wiring diagrams.
Pro
Joined: Oct 2012
Posts: 613
Likes: 3
Oh Dear God....this old wives tale just won't die, will it?
The oil pressure switch is wired in PARALLEL, NOT SERIES with the fuel pump circuit. It is there as a backup in case the fuel pump relay fails. It will supply voltage in the event of relay failure to the fuel pump circuit once the engine reaches approx. 4 psi during cranking so the engine will still start if the relay quits.
If the relay is functional, the engine will start and run with ZERO oil pressure....well, until it seizes anyway. The oil pressure switch is NOT a failsafe to "save" the engine in the event of a drop in oil pressure, nor is it required to start the car if the relay is functioning. Bypassing it is a complete waste of time.
See Factory Service Manual for wiring diagrams.
The oil pressure switch is wired in PARALLEL, NOT SERIES with the fuel pump circuit. It is there as a backup in case the fuel pump relay fails. It will supply voltage in the event of relay failure to the fuel pump circuit once the engine reaches approx. 4 psi during cranking so the engine will still start if the relay quits.
If the relay is functional, the engine will start and run with ZERO oil pressure....well, until it seizes anyway. The oil pressure switch is NOT a failsafe to "save" the engine in the event of a drop in oil pressure, nor is it required to start the car if the relay is functioning. Bypassing it is a complete waste of time.
See Factory Service Manual for wiring diagrams.
Last edited by GQ-ROD; Nov 14, 2012 at 07:56 PM.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Extended Cranking time -especially when the oil is hot. Normally, when you "key on", the pump runs ensuring proper pressure in the system. While pressure remains in the system for hour...even days, it isn't at spec w/o the pump running and the first couple fires of the injectors will quickly kill that pressure. in short, w/o the relay functioning, there won't be enough pressure in the system to fire the engine, and there won't be until the oil pump can build about 4 PSI, trip that switch, and the fuel pump will then turn on. In cold weather, 4 PSI can come quickly. With HOT oil, it could take some cranking.
You're not kidding. That "lore" is a persistent bastard.
Pro
Joined: Oct 2012
Posts: 613
Likes: 3
Extended Cranking time -especially when the oil is hot. Normally, when you "key on", the pump runs ensuring proper pressure in the system. While pressure remains in the system for hour...even days, it isn't at spec w/o the pump running and the first couple fires of the injectors will quickly kill that pressure. in short, w/o the relay functioning, there won't be enough pressure in the system to fire the engine, and there won't be until the oil pump can build about 4 PSI, trip that switch, and the fuel pump will then turn on. In cold weather, 4 PSI can come quickly. With HOT oil, it could take some cranking.
You're not kidding. That "lore" is a persistent bastard.
You're not kidding. That "lore" is a persistent bastard.
Race Director
Joined: Dec 2000
Posts: 17,551
Likes: 26
From: El Paso Texas
Although....on a Crossfire....pressure will fall off to zero in a couple of seconds after the pump stops running. Quite normal. Regulator is a "pass through"....ie....metered orifice variety.