• From: Elverson, PA
  • Registered: 2017-08-15
  • Posts: 1,142

Topic: Bi-fuel (CNG/Gasoline) 6.(x)l Vortec engine control

B.L.U.F.: what engine control system would I need to run this engine standalone, if I were to put this into a racecar? I believe the OEM GM injection system (like rails and injectors) is likely still present, just never used.

BACKGROUND:
I purchased an Express 3500, originally from GM as Bi-fuel, but which had the ability to run on gasoline deleted when built - before delivery.

Regardless, it came with a gasoline tank and lines underneath. The tank had rusted at the fuel pump opening.

The engine control system that remained switched from CNG to gasoline about every 100 starts - regardless that the ability to actually run on gasoline had already been deleted. I could get it to start again: I had to disconnect the battery cables and connect the ends together, and when I reconnected the battery it would run again; until one day, when it just didn't.

That - the switching - was a design feature of the Bi-fuel system. In original, complete configuration, it would switch to the _other_ fuel - whatever hadn't been used when running or starting, which is why the tank had about a quarter tank of gasoline in it. I removed the gasoline tank and lines as I had intended to add two CNG tanks to extend the vehicle's range beyond the f'n ~90 miles the onboard tank gave it, but I wound up scrapping those two Civics because I needed sort-term money.

Conveniently, it came with a 4L80e transmission, which I need for a different vehicle.

So that leaves a GM 8-cylinder engine with ~90k on it, that ran really well - until it didn't start.

So many engine swaps. I have to think this would be a reasonably original candidate, though definitely not straightforward. It came in a 1-ton Express, so it's pretty strong; and probably a gas hog.

The van still has the cat- that wasn't deleted - so I think I zero out the purchase price of the van when I scrap the shell.

Any ideas?

  • From: Queens, NY
  • Registered: 2014-05-17
  • Posts: 604

Re: Bi-fuel (CNG/Gasoline) 6.(x)l Vortec engine control

if its all there, maybe can just get a gasoline ecu that would have come with it. Otherwise probably like Holley terminator system. Or more DIY like rusefi, megasquirt, speeduino, etc... If harness is there, would splice the end of it to the ecu of your picking.

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  • From: Elverson, PA
  • Registered: 2017-08-15
  • Posts: 1,142

Re: Bi-fuel (CNG/Gasoline) 6.(x)l Vortec engine control

So from what you mentioned, I think I'm looking for an ECU from a GASOLINE ONLY Express 3500, yes? That would make sense to me.


I asked a GM Service advisor what would have been deleted on the line when the gasoline portion was deleted, but it had been so long since manufacture, that dealer never sold or serviced any of them, so he had no idea what would still be there, or what would have been removed on the line.


Conveniently, with respect to fuel injection rails, I can just open up the dog box and the hood and look - when I get a minute. I think I see two different color plastic things on the one bank that's easier to see, but I don't know exactly what they are; I'm wondering if one set is coils, not injectors. Dunno.


Thanks for the input!

  • From: Queens, NY
  • Registered: 2014-05-17
  • Posts: 604

Re: Bi-fuel (CNG/Gasoline) 6.(x)l Vortec engine control

Lemon_Newton-Metre wrote:

So from what you mentioned, I think I'm looking for an ECU from a GASOLINE ONLY Express 3500, yes? That would make sense to me.


I asked a GM Service advisor what would have been deleted on the line when the gasoline portion was deleted, but it had been so long since manufacture, that dealer never sold or serviced any of them, so he had no idea what would still be there, or what would have been removed on the line.


Conveniently, with respect to fuel injection rails, I can just open up the dog box and the hood and look - when I get a minute. I think I see two different color plastic things on the one bank that's easier to see, but I don't know exactly what they are; I'm wondering if one set is coils, not injectors. Dunno.


Thanks for the input!

Had another thought also, the harnesses would have labels, like the engine harness. see what it shows up to be. As well as the ecu should have labels, there is probably ecu tag list somewhere saying what each does.

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This car....Is said to have a will of it's Own. Twisting its own body in rage...It accelerates on.
1978 Opel/Buick Isuzu(C>B>C>B) , 1996 Nissan Maxima OnlyFans (B) , Sold 1996 Ford Probe GT(B),