Just finished putting everything together for the conversion, 5.7 vortec, and NV4500. But for some reason the engine will only start for a few seconds and then die. For those few seconds it runs great but thats all I get, a few seconds. I'm about stumped, the only code I can get is that my EVAP system has low input. If anyone can offer any help I'd appreciate it.

sounds like a fuel problem to me!;)

Sounds like your fuel pump is not running once the engine fires. It certainly runs when you put the key to "on", to pressurize the lines, but it seems to be cutting off once it fires up...

Probe the voltage at the pump and the fuel pump relay, and that should give you a place to start.

what year motor and vcm are you useing? how many seconds would you say it runs? one or 2 then it might be the vats (vehicle anti-theft system) did you do anything about that? i have a 99 vortec in my jeep. i run a 97 vcm to get rid of advance evap and vats systems.

Yeah, Fuel pump was one of my first guesses too. But since it's external I can feel that it's still pumping when the switch is at run. And I know it's the right pressure as well. I talked with someone from BTB Products today who mentioned the VATS but he acted like the only solution was to mail him my computer with a check for 285 dollars for reprogramming (and a wait of at least 5 weeks.) The engine I was told is a 96 and the 'puter is unknown except for that it is for an automatic, which I was told a dealer could reprogram for a manual. This is my first time messing with any computer controlled anything so if anyone knows anything else at all about the whole reprogramming process or what year computer would work best with this engine it'd be great. Thanks for the help so far anyway!

you do not have to have the computer reprogramed if it had a auto and you are going to a manual. the other way around you do. i bet it is your vat's system. sunray engineering in wetherford tx knows how to bybass the vats so you do not have to have the vcm reprogrammed but i can't remember how he said he did it. you might contact them and see what he says. when i first hooked up my 99 with the 99 vcm it did what you said yours is doing. it would cranks and imidiatly shut off. it was the vats system. i went with a 97 computer and it got rid of it. wngrog knows sunrays # so check with him.

Thanks, I e-mailed wngrog and look forward to the results. My only fear is the ominous feeling that this is but the first of many worms to escape from the can I am opening. But who cares it's too much fun. One more question, what is the best type of line to run from my charcoal canister, fuel line, vaccum line, what exactly? Thanks again!

If the engine truly is a '96 it does not have a VATS system. Can you download the VIN from the VCM and confirm what year it actually is. It certainly does sound like the VATS.

And high5 is correct -- you don't need to reprogram the VCM when going from an automatic to a manual. BTB just wants to get your $$ My '96 5.7L Vortec and NV4500 have run great for almost five years now.

Yeah, I have not had even a remotely pleasant experience with BTB. And no, I don't know how to pull the VIN. I don't know if the computer is a '96 or not, I have just been told that the engine is. They both came from a very reputable local salvage yard, but I don't think they're a matching set, you see I didn't purchase them, a friend did and then sold to me, so I don't know exactly if any of my model years are correct. By the way Medusa, are you the one with the Green Colored FJ with the very detailed website? If so let me tell you nice job, and you've been very helpful to me for a while now. Thanks again!

wouldn't be the neutral saftey wires not tied together? just wondering since it's an auto engine/computer that was switched to a stick.

dave

It is my understanding that the VIN is programmed into the VCM. When I start my OBDII scanner, it automatically reads and then displays the VIN number. If you can get the Vn from the VCM, you should be able to determine the model year.

I hate these third party engine deals. I bought a '99 5.7L Vortec from a guy and later discovered that the block was broken:mad: :mad:

Originally posted by BarnWrencher
I talked with someone from BTB Products today who mentioned the VATS but he acted like the only solution was to mail him my computer with a check for 285 dollars for reprogramming (and a wait of at least 5 weeks.)
:laughing: :laughing: :laughing:

Originally posted by davefj40
wouldn't be the neutral saftey wires not tied together? just wondering since it's an auto engine/computer that was switched to a stick.

dave

yes the neutral safety switch wires get tied together. i run a th400 but i did mine anyway. i don't need no stinkin nuetral safety switch! :D

Neutral safety swich is a good idea, but I'm not going to look into it until I solve a slightly more pressing problem. I had a local dealer run the service number on my computer today and found out that even though it and the engine were sold as a pair, the computer is for a 98 S-10. now I really don't know the dynamics of everything the computer does but it doesn't seem to me that a V8 '96 will work with a V6 '98. So I found supposedly a 96 V8 computer for salvage and I'm going to try it tomorrow. Does anyone know if these computers have a born on date or anything. Someone told me if they sit up to long with no battery they reset, but I didn't believe 'em. I hope I'm right. Guess I'll find out tomorrow.

Originally posted by BarnWrencher
Neutral safety swich is a good idea, but I'm not going to look into it until I solve a slightly more pressing problem. I had a local dealer run the service number on my computer today and found out that even though it and the engine were sold as a pair, the computer is for a 98 S-10. now I really don't know the dynamics of everything the computer does but it doesn't seem to me that a V8 '96 will work with a V6 '98. So I found supposedly a 96 V8 computer for salvage and I'm going to try it tomorrow. Does anyone know if these computers have a born on date or anything. Someone told me if they sit up to long with no battery they reset, but I didn't believe 'em. I hope I'm right. Guess I'll find out tomorrow.

well if it is an auto tranny vcm you better worry because it will not start at all if you dont.

This VCM should be a perfect match to my driveline. transmission and all. My wiring harness doesn't have any neutral safety switch wires anyway. If it does, someone got to them before me.

Originally posted by BarnWrencher
This VCM should be a perfect match to my driveline. transmission and all. My wiring harness doesn't have any neutral safety switch wires anyway. If it does, someone got to them before me.

the nutral safety wires are in with the wiring for the tranny position sensor connector on the side of the tranny. atleast it is on mine. once you get the new computer if the motor won't turn over then that is where i'd start looking.

Great, it sounds like a plan to me. Thanks.

I believe there were two computers used on the Vortec in '96. The numbers on these are: 16208546 & 16244210. In '97 there was one computer: 16229684. I just verified my '97 has this number on the computer. Any of these computers will work for your 5.7LTR Vortec. Any security feature in these computers can be bypassed in your harness. I am not sure how to do this yet because GM is out of the service manuals for the '97 Vortec - which is the one I have ready to drop into my FJ40. You do not have to reprogram for the manual transmission as Jack stated. There is a feature that will shut off fuel pump if oil pressure reads too low, but I think you said you can feel your pump working. If your engine turns out to be a '98 or '99 5.7 LTR the above three computers will still work and actually are the best solution because of Pass Key security.

Greg

I got py computer today from another junkyard, it completely did the trick. Everything is running like a sewing machine now. Thanks for all the help.

Originally posted by BarnWrencher
I got py computer today from another junkyard, it completely did the trick. Everything is running like a sewing machine now. Thanks for all the help.

cool! glad everything worked out.

Good news, Barnwrencher.

Your experience should be remembered. A common solution to the VATS problem in '99 and newer engines is to replace the VCM with a '96 or '97 version. What do the junkyards do when they later sell the '96 or '97 engine that they previously raided the VCM from? It seems now to be very important to make sure that you know "from whence came the VCM".:mad3: