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Old 04-01-2007, 03:44 PM
dieselcruiserhead dieselcruiserhead is offline
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Need some help with 1986 GM 305, TBI or Carbed???

Hi Guys,
Just scored a van last night, 1986 305, 700R4, G-20 model van but it's only 5 lug wheels and a 10 bolt in the rear... ? Only $350 and 67K original miles and actually has a pretty good body (minor surface rust) and interior. Not sure what I am going to do with it, maybe put the setup in something... I am actually psyched to maybe have as a van as I like that setup (the smaller motor, faster gearing and the OD for cruising)...

Got it so cheap because it has been sitting for 10 years.. So I took my time, even changed all the fluids even though they all look pretty good, and it fired right up.. Only thing is that, whether its Carb'd or TBI, it is dumping fuel down, can borderline almost not even run because there is too much fuel... I'm sure the sitting was not good for the fuel system..

I was under the impression that TBI started in 1987.. But on this van, even though it is an 86, if it is TBI, it has some clicking and electrical harness plugged into the carb/throttle body... Has an O2 Senson off one of the manifolds, and what looks like a heat riser on the pass side manifold. It is a van so a little hard to get in there and see for sure, even with dog house removed.. It has a HEI, but I know these came on both carbed and TBI models.. It has a mechanical pump, but a metal line from the pump to the carb/TBI unit that looks like it might be higher pressure than the normal carburetted pressures... I thought TBI were electrical pumps for some reason. Then, I found something that looks like it probably is a computer under the driver's seat...

So it is starting and running, but again literally dumping fuel. Almost as soon as it starts. I am wondering if it has an overfueling setting for cold starts or something like that that it is stuck on?

Do TBI units go bad? Are they interchangable, all years? This one looks different than the one I have seen on a '90 4.3 V6... I have a friend with a few V6 TBI units lying around. These are probably the wrong size / rating for the 305 V8 TBI? I guess my options are go to the JY and find a 305 and pull the TBI unit off that and bolt it on is probably easiest?

Thanks guys,
I really know little/almost nothing about these...
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