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Adam Mclaughlin 08-18-2003 06:35 PM

1996 Vortec Engine Swap - need Help
Okay guys.

I bought a 1996 Vortec 350 out of a suburban and I swapped it into my 1989 TBI Chevy truck.

I got the wiring harness, computer, complete motor and all of the sensors.

I hooked up all of the wiring as shown by all data, and I did this as follows.

The pink wires are hot when in run, the orange hot all of the time, and the yellow hot when cranking.

I have a the motor cranking when I go to start it, and I have spark, along with 48 psi of fuel pressure when system on, engine off.

The darn thing won't start. I have check engine light, so I know it is alive, but I am not sure why it won't start. On the injectors I show about 9 V when cranking from the open connector.

What gives? Does it have VAT that must be in the loop to make it start?

In other cars I have done similar swaps the machine at least starts and runs for 2 secs before the VAT makes it drop out. This thing does't do anything but crank.

I did pull the distributor out and re set it when I noticed my original one was cracked. I brought the motor to TDC of cylinder #1 and then aligned the distributor to point at pole #1 in that corner of the cap.

What gives guys? I got a couple of puts out of it, but other than that I have no signs of engine life.

I have access to another 1997 Vortec I could compare too, but this isn't helping much at this point.

Any suggestions out there?

I want to get my truck back on the road!


DoubleVision 08-18-2003 06:39 PM

Just to be sure, you did bleed the air out of the fuel lines?

Adam Mclaughlin 08-18-2003 06:56 PM

I cranked it like a son of a *****. I am sure that the pump circulated everything through the lines a couple of times.

I have fuel pressure of 48 at key in, engine off and just above 40 when in cranking.

What gives?

Is there some kind of special distributor alignment method that the chilton's book doesn't show me? I did it their way for a spell. Not even a sputter of life, which makes me think that the answer is something silly simple.


DoubleVision 08-18-2003 07:06 PM

if there`s air in the lines you can crank it here to 2050 and it`s not gonna start. the pressure reading you get can be air pressure. the fuel injection rail will have a valve stem, just like on a tire, that bleeds the air out of the system, look for it on your fuel rail, it should have a cap on the top of it that just screws off, remove the cap and press down on the center of the valve, but keep your face out of the way if you don`t you`ll get a face full. if it bleeds out air first, keep bleeding it until there`s no more air. This is why injected vehicles have these, if they run out of gas there has to be a way to get the air out.

bluesman123 08-18-2003 08:07 PM

I don't believe you have enough fuel pressure. 48 PSI will work for the old TBI system, but I believe the 96 vortec uses the MFI system that requires 63 psi. I did a similar swap with a 98 L31 into a 91 Sonoma, and had to replace the in-tank fuel pump. Once I got the higher pressure it fired just fine.


drlindz 08-18-2003 08:59 PM

I had a similiar problem once and it turned out to be the air inlet from the mass air flow sensor to the intake plenum. I DIDN"T HAVE IT HOOKED UP! LOL!

outlaw17 08-18-2003 09:20 PM

I was just working on a 99 Yukon yesterday and I tried to start it with the air plenum from the air filter and MAF sensor not on the engine and it would not start , do you have it on yours ?

Adam Mclaughlin 08-19-2003 08:50 PM

Yeah, we're going to try to change the in tank pump AGAIN!!

I got a junk yard fuel pressure pump this time, no kragens cheapies.

I did have the MAF disconnected for some tests, and on for others. I didn't notice a difference, the darn thing still wouldn't start either way.

Wednesday night I will drop the tank again and change the pump, then wire up everything else and see where we can go with it.

Wish me luck guys!


bluesman123 08-20-2003 10:16 PM

Be sure you get the right pump. If it doesn't come from an MFI system it won't put out enough pressure and you'll be back where you started.

Adam Mclaughlin 08-22-2003 09:13 PM

Hiya Fellas,

Okay, I got her runnng, but it runs very poorly. I am going back to the junkyard to get the wiring connector to connect up the scanner tool and see what the obd has to suggest.

I have noticed that disconnecting the MAP makes no diff, while every other sensor has an affect so this may be a place to start at....

Will know more by Saturday night.


capps 12-31-2004 07:43 AM

Adam how did your swap turn out? I am doing a similar swap with a 97 model vortec.

bluesman123 12-31-2004 05:09 PM

You sure picked the right year engine...from 98 on they get real difficult if you need to get it smogged. I had to "convert" a 98 to a 97 to pass the CA smog police, but I've been driving it for 9 months now and it's great.


Adam Mclaughlin 12-31-2004 10:32 PM

I got it all smogged last month. Was actually very easy, the only thing stopping me right off of the bat was the lack of EO number on the Air Raid air filter.

I was actually so impressed, or surprised by how little the ref knew, that I plan on taking my four more ASE exams to get the cert. so I can appear more competent to him. He didn't understand my wiring when I told him I went through the EECS program at Cal.

I used the original truck wiring harness out of the donor, as well as the original computer. No re-programming, or changing anything. Just hooking up the right wire to the right spot, and everything is well.

1996/1997 Vortec 5.7 in a 1989 Chevy K1500, using a 700R4 instead of the 4L60E.


capps 01-02-2005 07:27 PM

Did you have to change your fuel lines? I am going from a carb to injection on my build. The late model lines are on the driver side frame and mine are on the passenger side. It looks like it would be easier to run new lines on the driver side.

bluesman123 01-03-2005 09:56 AM

I didn't change my fuel lines, but I started with a TPI setup that already had steel supply and return lines. If your's started with a carb, I would change them. You will be going from 10-13 psi to 60-65 psi and there might be a connector somewhere that can't handle it.

It will definitely be easier to plumb it if the lines come up the driver's side.


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