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Discussion Starter · #1 ·
I recently bought a 90 RC for a decent price but the TBI it has is awful. I regularly go camping in the mountains and this thing barely pulls its own weight much less a little pop up. So I just installed a 4 barrel, new distributor and all that fun stuff. The only issie now is the fuel pump only turns on for a split second to prime the line then shuts off. Does anyone know how to wire this so that it will work properly?
 

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howdy and welcome // well for one the 14 psi out of the pump will drown the carb out , the ASD relay that turns the pump ON gets its signal from the TBI Dist pickup , l can tell you didnt "think" this thru before ripping its guts out , so the ASD relay can be bypassed to Key power , your still gonna need a fuel pressure Reg with return line to drop the fuel pressure to 5 to 7 psi , or you could drop the tank and throw the pump away and either run a frame mounted pump or engine mounted , theres a Whole Howto writeup on how to do all this stuff [ which l cant find ]

l would have tried to fix the TBI problems first then gone from there
 

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I really dont understand why people get rid of TBI and go to a carb.....keep in mind that if you hook the fuel pump up to key power it will run anytime the key is on...so if you crash and the engine shuts off your fuel pump will still be pumping, that can be rather dangerous. A 90 engine may still have the cam eccentric behind the block off plate for a mechanical fuel pump or you can buy a kit to add it, or as DODGEBOYS said add a regulator with return line to what ya got. You didnt mention if you have a 318 or 360 or what size 4 BBL carb you got, but I suspect you're not going to be too impressed with how it runs.
 

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Discussion Starter · #4 ·
I already got a regulator ive done a lot of research before I bought everything. The TBI wouldve been more trouble than its worth all the o2 sensors have been removed because the person before put an aftermarket exhaust and they just cut the wires. I'm 17 I don't know how to tune a TBI in my opinion something I know how to work on is more reliable than something I can't. The motor in it is a 318, i bought a edlebrock performer dual plane and I already had a 650 cfm carb from my nova thats out of order right now. And I ordered a holley truck avenger carb so I won't flood all the time when off roading. Another point, that TBI fowls my plugs every 2 weeks. And the research ive done you need a scan tool to tune it and you can only tune it so far. So that asd relay is that an internal deal or is that a relay I can find on the firewall or the fender? I believe i have 4 relays on the fender 1 of which is the starter relay, the others I do not know.
 

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ASD is on the fender, it fouls plugs because its running full rich because of the lack of 02 sensor. No scan tool needed to "tune" it, yes it is true that you are pretty well set with factory timing and cam, however unless you were going to swap cams anyway that's a non issue. The 470 truck avenger would be about right for a 318. 650 is too much imo. TBI only has one 02 sensor, if headers have been added you can add a bung to install it, I'm not trying to talk you out of carb just trying to help you understand why you're TBI isn't working. Be prepared to tear that Holley apart when you get it as all the holleys I've ever gotten are way too rich out of the box.
 

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Discussion Starter · #6 ·
Ok, yeah i know I just don't like edlebrock carbs as much I find them harder to tune. Well thanks for the help on the relay I'll let you know if I figure it out.
 

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Discussion Starter · #7 ·
Also I said that wrong ive already bought and replaced the o2 sensor with a new one and it still runs super rich thats why I said screw it and went with a carb
 
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