daviprit

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I've put a 98 LS1 engine into a 53 Chevy Truck. Before I sent the Computer off to get programed it would start and run but rough. I had the computer converted to Speed Density, Vats Burned out, and set up for an adjustable fuel regulator. I have a 70psi vortec fuel pump with Professional Products Rails and Regulator. Fuel Pressure Gague is showing 58psi. The engine will fire right up but starts going dead after about 3 seconds. During that time if you try to give it gas you can hear the motor trying to suck air but it chokes down and dies. I've tried hooking the fuel pump up direct to the battery bypassing the realy but still won't stay running. I hooked a scan tool to it and its not showing any codes or history of codes. I've also stuck a screw driver to the injectors to listen to them and as the engine starts dieing the injectors clicking slowly starts to slow down with the engine rpms. If anybody has any suggestions It would be greatly appreciated. I've also hooked up a VATS module to the Painless wireing harness to see if that would solve the problem but it didn't, it also has 14 volts when running for those 3 seconds and 12.2 while not running.

bczee

iTrader: (12)

I know the number 1 answer or suggestion for this type of problem is usually the VATS...

I know there has been a few threads with people saying that they had the VATS or Sim done and most of the time, going back, it was the VATS..

If it will startup and run for a few second.. you know that everything is connected right.. Sensors, fuel is there, spark, injectors... etc.. Who did the PCM programming ? maybe try that route again. Give them a call and work with them again on this..

daviprit

Fuel injection specialties, San Antonio, Tx did the programing. They asked me to hook a Scan tool to it and look for a VATS code but it wasn't there. Thats when I went ahead and hooked up a Vats Bypass Mod to see if in fact it was that but still the same thing.

Frost

iTrader: (45)

they could have turned off error reporting for the code but not actually disabled it, in which case it will do as you describe and not set a code. I have seen this more than 1 time before...

daviprit

But shouldn't it run if thats the case, when I put the Painless Wireing Supplied Vats Bypass Module on?

Old Geezer

iTrader: (3)

What's the FP gauge doing when it's dying?
How long, if any, did the engine/injectors sit, B4 you fired it up, again?

daviprit

Holds pressure right around 60 psi then after it dies it holds the pressure for a couple of seconds then it falls to zero. Then you can turn the key off and attempt to start it right back up and it will but only for a couple of seconds then it'll die again.

Big Geek

iTrader: (2)

This may sound silly but is the fuel pump getting the proper voltage?

Jim C.

daviprit

Haven't put a Volt meter on it but I'll check.

frojoe

iTrader: (10)

So fuel pressure dies like this, but you previously stated that even when the pump is powered directly from the battery, it still doesn't work?

daviprit

Correct. When its wired directly to battery bypassing the relay and computer it holds around 60psi but when you start the truck up it still dies after about 3 seconds and still has 60psi.

frojoe

iTrader: (10)

Does it constantly hold pressure for indefintily after the engine dies, or does the presure die off a bit after (i thought I remember you saying that the pressure does die off)?

I aswell lean towards the VATS issue. When it does start, how does it run? Catches really quickly and doesn't seem to have issues? When the engine is dying, is it slowly stumbling or does it just stop?

Also, I think when I tuned mine with HPTuners, there was no option for switching off a "thrown VATS code", really the only thing you could disable was the actual VATS-checking feature in the PCM..

sciff5

iTrader: (1)

I'm gonna say vats.. I used a vats bypass box for my RX7 and it still didnt work. I got Vats tuned out and the car started first crank and ran fine.

malott442

This may sound silly, but did you check your fuses? I had the exact thing happen to me and it was a fuse for the computer.........

Replaced the fuse, and 8 months later still hasn't happened again.........

Frost

iTrader: (45)

I don't know, but I have tuned 2 swaps that had the "VATS Bypass" module but I still had to shut it off in the PCM. One of those cars I was referring to in my previous post. I didn't think it was VATS because it didn't set the VATS code, but after I dug into the file I saw that error reporting was turned off for the the DTC (?) but VATS was left active in the PCM.

frojoe

iTrader: (10)

Exactly.. the VATS feature itself must be turned off, so if your tuner says to scan it to check if it's throwing a VATs code, well, I don't think there even is a DTC for VATS?

As for VATS modules, why bother? You're going to have to get it tuned anyways to wipe DTC's such as rear O2 sensors, EGR, etc, so why even bother with the module, why not go right to the source and turn of VATS?

Slvr00Bird

iTrader: (2)

I think it's a bad flux capacitor.. common on that year motor, especially in a truck..

Frost

iTrader: (45)

There is definitely a DTC for it if it is acting. Its in the 1600 area and includes theft deterrent in it's description.

frojoe

iTrader: (10)

My mistake, I just did not remember seeing it when I tuned a while back.

bgblockelcamino

iTrader: (9)

how are the grounds? i had it happen on my brother's vette. i left one ground wire off. after that it ran fine. just a thought.