Hi everyone, first post, and I need help. Bought an 82 with crossfire injection a couple weeks ago that had been sitting up for about 2 years. You can pour fuel into the throttle bodies, and it will crank and run like a champ, but will not put another drop of fuel out until its about to die. It will then inject from both injectors, just a second or two injection, sometimes stays running, most of the time dies on me.
I had a TBI truck in the past, and the fuel pump was the problem I experienced with it. The fuel pump was putting out 10 lbs, but I went ahead and changed it to an 85 vette pump and cleaned out the tank good. Filter was good. Nothing different up front. Fuel pump relay turned on with the key to pressure up, then started pumping good again when turning the engine over. Pulled both throttle bodies apart and checked the injectors, cleaned them good, put back together. Fuel pressure good at the throttle bodies. Adjusted TPS to .530 reading on multimeter. Checked codes and got a Code 15 and a Code 34. Installed a new MAP sensor, installed a new coolant temp sensor, installed a new ignition module. Checked all wires going into these sensors and they all seem ok. Cleared Codes. Still doing the same thing.
The guy I got it from said it was professionally restored three to four years ago, and I think Corvette South in Meridian, MS did most of it. Anyway, looks to be pretty well done from all I can tell. He did say that it had some kind of security system on it that shut it down on him once until he put the key in the door and did something.
I know I'm going to feel really dumb once I figure out what it is. Would prefer to keep the fuel injection for gas mileage and longevity if possible. This is my first Vette, and I want to drive it! Please feel free to e-mail me. HELP!!!

 

You said you installed a 85 vette pump into your 82? If that is so, the 85 pump is a much higher pressure than the stock Crossfire TBI pump (TPI vs TBI). I may have misread it though.

Will

 

the 85 pump is what you want .that part is good but you may have a ecm problem.i would do some reading here http://www.crossfireinjection.net/index.htmi also would join http://www.crossfire.homeip.net/inde...re.homeip.net/

 

make sure you don't have any vacuum leaks. With the 832 vacuum lines in those things 1 is bound to leak. I had similar problems with my computer controlled carb '81, the vacuum leak will throw off the computer and make it idle like poo then die. Fixing the vacuum leaks fixed everything.

 

It could be a couple of things. Lets start from the beginning so you don't get confused.

Check the basics. Are all the fuses okay? Example fuel pump, 2 TBI fuses and the one fuse by the ECM?

Next we need to figure out if the ECM is working or if its something after the ECM thats the problem.

Lift the hood and remove the air cleaner. When you first get into the car turn the key to "on" but don't crank it. Do you hear the fuel pump buzz for about 2 seconds (from behind you)? Immediately after the fuel pump buzz do you you hear a noise from the injectors (like a short buzz sound) for about two seconds? The buzz from the injectors is the prime pulse. If this doesn't happen your problem is likely in the ECM or the wiring to the ECM.

I'm not going to get into more until I hear back on the above.

Just a note of caution, don't mess with any of the settings on the TBI's.

Jim

 

Hi again, and thanks for input! The fuel pump relay turns the pump on with the key, its buzzing in the tank, but there is no prime pulse of the injectors. All the fuses test ok, except for the instrument light fuse, which does not have power on either side of the fuse slot for some reason. Pulled one of the injector fuses and cranked it by pouring in gas, one injector shot when it was dying and the other did not. Replaced fuse and both started shooting again.
On the TPS, I took notes of where it was set (.570), should I go ahead and put it back? Only reason I adjusted was that I was told this was out of tolerance by a local mechanic (30+ yrs), but it is still having the same problems as when I first started. I definitely won't adjust anything else til its running.
Guy I got it from said there is a factory security system on it that I am going to try and check out tonight if I can get off work in time. Think this could be the trouble?
I am also going to check the 832 vaccuum lines. When it died after running 30 seconds or so, I heard vaccuum running out of something under the dash. Figured it was the a/c controls or a tank for them under the dash, but now it sounds more like I better look at this.
One more question: On the smog system pipe that runs down by the RH manifold and exhaust tube, where is it supposed to end? Some nut has cut it off with a torch and tied it to the fuel return line with a zip tie. Know this is getting very confusing, but I am trying to make sure I have all the loose ends tied up before I pull the trigger on a new ECM.

 

So are both injectors spraying now? No prime pulse is almost always the ECM, fuses, connections or Oil Pressure sensor.

The TPS should be at .528 plus or minus .007. I don't think .570 will cause the problem you are having. Just to make sure you do mean .570 not 5.70 right? And be sure its in the range of .570 because if its much higher then that your car won't start...ECM needs this reference accurate. I went back and fortth with some one trying to gets something fixed a while back and it turned out he had his meter set wrong. The TPS range is .528 to 4.5 at wide open. Maybe you should reset it.

The vaccum leak under the dash may or may not be a problem. Its all feed through the vaccum connect point on the intake just behind or near the rear TBI on the driver side. Unplug the vaccum line there and plug the port on the block...eliminates all vaccum leaks while you try to figure this out. its probalby why you got the MAp code. If there isn't enough vaccum pressure in the mainfold because of a leak the system may not send fuel. You will know once you plug it off. You should have a constant 20 psi on the hose going to the MAP.

I am not sure if its your alarm. i have never had a problem with my alarm. I would think nothing would happen if the alarm was tripped. I see nothing in the diagram that indicates the alarm kills the fuel pump relay. It interupts the starter.

The only think that kills the signal to the fuel pump relay and fuel pump is the oil pressure sensor. Its bell shaped and located on the driver side just behind the exhaust manifold. That sensor detects if there is is good oil pressure. If the oil pressure is low or gone it will kill the fuel pump. When you crank the engine does the oil pressure on the guage climb above 12? It could be your problem... clean the connector.

Re: Pipe. Thats the smog pipe it takes from the engine and puts hot vapor into the exhaust near the cat converter. It won't cause your problem.

More later..

 

This may help

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Both injectors are spraying, connector on the Oil pressure sensor has 12.87 volts across it, and is jumping up to over 40 lbs of oil pressure while turning over. Thanks for the diagrams!!!

 

Your confusing me. So do both injectors now spray when you crank the engine?

Note in the test above that the ECM gets a reference pulse from the distributor. If you are not getting a prime pulse or spray on crank follow the instructions. I have seen a bad or loose connection on the distributor on the driver sdie cause this problem. The reference gets sent to the ECM, follow the wires on the diagram to the appropriate connector. make sure the wires are not broken or corroded. You need to go step by step incase something you do temporarly resolves the problem. Example clean the connector on the distributor then try to start it. Don't go ahead and clean the distributor connector and ECM connector at the same time because if this works temporaily you won't know which of the two fixed the problem. do that with everything, one disconnect or repair at a time, eg plug off the vaccum port and try it, don't do two things at the same time.

 

No, sorry. They only spray when its dying. They are acting together. Still no prime pulse at all, will only start when fuel is poured in.
After looking at troubleshoting and diagrams, I am leaning toward ECM being bad. Will check connections first to be sure.

 

If its the ECM. Check the prom first, make sure its seated properly. The problem with these cars you never know what the previous owner did.

Just in case you already don't know it, there are several large connectors behind the cover on the firewall passenger side, follow the TBI and IAC wires and you will see where they go in. Open it up and clean the connector.

That tube you mentioned goes into the cat converter...is your cat gone?

 

the vac noise you are hearing maybe for the headlights.the switch is on the dash between your legs .

 

I have an 82 also. Here's a few problems I have had. 1. Fuel gauge reads more than half a tank when there is no fuel in tank. 82 corvettes have an inner liner that is made out of a plastic. With time the plastic liner will collapse slightly at the rear of the car area. When this happens the sending unit float will hang up on the liner. When this occurs the gauge will read falsely because the float on the sender unit cannot drop towards the bottom of the tank. I put a thread on this a few years ago and how to fix the situation. You may do a search. 2. The other issue may be the rubber tube that is connected to the electric fuel pump and the metal tube that that comes out of the neck of the top of the pickup assembly. This rubber tube with time becomes sloppy and brittle to the point it will just fall off. If this happens the fuel pump will work but it is just pumping it inside the tank. I would at this point concentrate on the fuel pump issue. To remove the pump without dropping the tank do a search as I posted how to do this without damaging the filler area or paint. After reading your post twice had you replaced the fuel pump with the 85 on this car? If so did you replace the fuel filter that mounts to the inner frame in the frame area that is just behind the front right tire. This is a filter about an inch and three eights round and about two inches long. This filter may be old and clogged
Good Luck!

 

If you are trulyconsidering coverting it to carbureted, this is the route I would take. I did mine 2 years ago and never looked back. I went thru 2 phases of top end upgrades before I stroked it to a 383. Even with top end upgrades you will be pleased with the results.

 

Just came out of the shop. Plugged off the main vaccuum port, no difference. Checked the 430 circuit, distributor reference pulse, at the ecm. Digital voltmeter did not register accurate voltage, but the bar under the numbers was jumping the whole time I was cranking on it. Hooked up an analog voltmeter, and the needle fluctuated some but slowly built up to a constant voltage of about 1.5 volts and seemed to hold there. Hooked the digital up again and the bar was jumping up and down quick, so I think its getting pulse. Checked continuity in all wires running from distributor to ecm, all good. Checked continuity in wires running between ecm and the injectors, both good. Hooked it all back up and still doing the same thing. ECM connectors were tignt and looked ok just looking at them.
I am headed back out in a minute to look for the factory security system. I did find the theft fuse and pull it, and the car still did the same thing. Tried to set the security system off by locking the doors with the key and popping out the T-top, but it didn't go off. I don't know if the security system is hooked up or not now. If it only affects the starting system, then it must be unhooked as the starter still runs fine.
Any more suggestions, or go ahead and try an ECM?

 

Are you 100% certain you have constant fuel pressure of 9-13 psi? If so it's likely the ECM. You did check the fuse beside the ECM right? Try pulling the fuse and cranking just for curiosity.

Lastly can you get a test light on each injector connection and see if it pulses while you crank the engine. No pulse would confirm am ECM problem. If there is a pulse it suggests fuel pressure maybe the problem.

 

If you are tired of guessing maybe you should go ahead and buy am ECM. It's cheap? Just over 100 bucks. Swap out your prom, they don't come with one.