Frankenstein Astro van

**fastblue231** · 07-06-2012

My name is Adam and im in Charleston WV. I have a Frankenstein Astro van; 93 body 98 awd frame 94 LO5 93 4l60e 98 borg warner 4472. 3:42 gears mostly everything is factory except the exhaust (open headers) and air cleaner (Edelbrock cheapo). I tuned my 86 olds delta years ago never really had much issues with it (mostly because its speed desity). This TBI 350 is tryin to get the best of me. Every thing seems fine except the AFR's. I can not get it to fuel right. The heavier the load the worse it seems. I put the LO5 injectors in the factory van throttle body because the throttle mechanism is slighty different. I dont see how this could be a problem Im fairly positive the bores are the same. Some one help me out before I slap a quadrajet on it. Or even better a 4bt in it.

**jameslleary** · 07-06-2012

Your not using the memcal from the 4.3, are you?

**fastblue231** · 07-06-2012

Naa used the whole computer that came outta the 94 c1500 with the V8. There were no tags on it must have been torn off at some point in the junk yard. I just stuck the adapter and 27SF512 in it this evening. Ive tried every program i could find that is remotely close. Still no luck. I did use the fuel pump outta the 98 van. Not sure what fuel pressure is. Ive tried higher and lower flow in the ecm and it don't seem to make much of a difference.

**jameslleary** · 07-06-2012

The fuel pump may be your problem. The 98 fuel pump is a high pressure pump for the Vortec...60 psi if I am not mistaken.
all small block TBI ran the lower pressure 13 psi pump. Only the 94-95 7.4 454 TBI ran the higher pressure port injection style pumps.

**EagleMark** · 07-06-2012

mostly everything is factory except the exhaust (open headers)

And your O2 sensor is in the collector, right next to open air? Not going to work...

Some one help me out before I slap a quadrajet on it.

We will help, but no reason to blurt out obcenities!

Or even better a 4bt in it.

I'd like to see that stuffed in there!

Ive tried higher and lower flow in the ecm and it don't seem to make much of a difference.

This is a setting not a tuning tool.

Find a stock bin for the motor and trans and go from there.

Go open loop or put an exhaust on or at least three feet of pipe after the O2 sensor.

Must check fuel pressure!!!

You changed the intake and throttle body so there may be a vacuum leak. Did you install and adapter? Sooooooooo many adapters cause vacuum leaks.

**jameslleary** · 07-06-2012

Originally Posted by eaglemark

we will help, but no reason to blurt out obcenities!

lmao!

**romac55** · 07-06-2012

How's that 60psi fuel pump gonna work on your Quadrajet ? LOL . I'd be checking the fuel pressure first ; sounds like it's away high . Be safe...Bob.

**jameslleary** · 07-07-2012

Originally Posted by romac55

How's that 60psi fuel pump gonna work on your Quadrajet ? LOL . I'd be checking the fuel pressure first ; sounds like it's away high . Be safe...Bob.

With what he has accomplished so far, I would say that he is smart enough not to try a high pressure EFI pump with a carb.

**1project2many** · 07-07-2012

You know, guys, I've used pumps capable of high pressure in TBI systems many, many times. As long as the volume of fuel it moves isn't greater than what the regulator can flow there isn't likely to be a problem. Just because a man is capable of lifting 100lbs doesn't mean he's lifting 100lbs every time he picks something up. As to using this pump with the carb you just need to install a bypass regulator to return unused fuel to the tank and knock pressure at the carb down to 7-10 psi.

OP, I agree that the O2 sensors should not be that close to fresh air. Disconnect the sensors and the ecm will not go into closed loop. If the engine runs better that way then close the exhaust or set your calibration to run open loop.

**EagleMark** · 07-07-2012

Originally Posted by 1project2many

You know, guys, I've used pumps capable of high pressure in TBI systems many, many times. As long as the volume of fuel it moves isn't greater than what the regulator can flow there isn't likely to be a problem.

I also use TPI in tank pumps in higher HP TBI engines with no issues, just has a higher return flow when fuel is not needed.

Even if the pump was stock though, fuel pressure is always a concern. Didn't meen to imply it was the pump.

**PJG1173** · 07-07-2012

Originally Posted by 1project2many

You know, guys, I've used pumps capable of high pressure in TBI systems many, many times. As long as the volume of fuel it moves isn't greater than what the regulator can flow there isn't likely to be a problem. Just because a man is capable of lifting 100lbs doesn't mean he's lifting 100lbs every time he picks something up. As to using this pump with the carb you just need to install a bypass regulator to return unused fuel to the tank and knock pressure at the carb down to 7-10 psi.

OP, I agree that the O2 sensors should not be that close to fresh air. Disconnect the sensors and the ecm will not go into closed loop. If the engine runs better that way then close the exhaust or set your calibration to run open loop.

X2 on the pump. I have a pump out of a 01 vortec in mine with the tbi regulator set at 13psi and I also have a vortec pump on my carbed toyota running 5.5psi through a bypass regulator. X3 on the exhaust need more pipe after the o2 sensor.

**jameslleary** · 07-07-2012

He didnt mention an extra regulator in line.
I too have ran carbs and and TBI off of MPFI pumps, I had to run an external regulator, though.
I agree with the o2 sensor being too close to open air...would be worse than an upstream exhaust leak pulling air in.
But, if he is running the Vortec pump straight to the TBI, this would cause issues as well.

**Six_Shooter** · 07-07-2012

Originally Posted by jameslleary

He didnt mention an extra regulator in line.
I too have ran carbs and and TBI off of MPFI pumps, I had to run an external regulator, though.
I agree with the o2 sensor being too close to open air...would be worse than an upstream exhaust leak pulling air in.
But, if he is running the Vortec pump straight to the TBI, this would cause issues as well.

A GM TBI won't need a secondary regulator, they are pretty good at regulating fuel pressure from a variety of fuel pumps.

**gregs78cam** · 07-07-2012

Originally Posted by Six_Shooter

A GM TBI won't need a secondary regulator, they are pretty good at regulating fuel pressure from a variety of fuel pumps.

I can agree with this, I have a MPFI pump in my TBI Truck using the factory('90) fuel lines, and TBI/regulator with no problems.

I did however have an issue with a bosch pump that would push enough fuel at a high enough pressure to overload the TBI regulator and make the engine run rich. I never got any real specs for it but it was from a AFI Kit that a buddy ordered.

**1project2many** · 07-07-2012

Sometimes people confuse what a pump can do with what is is actually doing. The only real time I've seen issues with a pump and TBI was a Walbro 255 pump on a model 700TB. Pumps were dying prematurely because the passages in the TB were not large enough and the pump was at some silly pressure all the time.

Even if the pump was stock though, fuel pressure is always a concern. Didn't meen to imply it was the pump.

I agree 100% with what you recommended. Just wanted to state what works in case anyone else had questions.