I have a sweet 91 RS convertible with a 305/auto. It is giving me some running issues. It is idleing high with a code 21 and getting harder to start. It has 162k for miles so it is time. I am thinking that the TBI unit needs some tlc. Should I get the kit and tare it apart myself? What about the injectors. I would rather just unbolt it and disconnect the lines and hoses and un plug the plugs and just bolt a new/rebuilt one down. I don't want to transfer anything over I want all new sensors. Are there places that sell such an animal and how much should I expect to pay. Holley makes a direct replacement for a 350 but not a 305. I just want it to run as good as it looks. Or should I just fix whats wrong with it and not waste any more money on stuff that doesn't need to be replaced. I was in the general engine form but after reading some from here I think I should have been here the whole time. I am eager to hear from everyone out there. Thanks

 

I would check the IAC first. if that checks out and you just want a factory rebuild go here http://throttlebodyinjection.com/

I used the same company for a q-jet once and it was flawless

 

If you plan on keeping the car I would suggest the injectors be cleaned. fuel injection connection aka FIC can clean and the TB itself have bushings installed as they tend to wear as they are cast alum. I would think a carb shop can do that. Add the rebuild kit and you will be fine.

 

Well it got worse. It was ideling at over 40 mph. It was a bitch to start too. Well after reading all the posts from this thread and the others I posted I decided to do what I origanally wanted to do. I replaced the tps and holey **** its fixed. I almost bought a new throttle body. I would still like to have the injectors cleaned but that will be later it is time to just enjoy the car. The 36 bucks I spent on the new tps was way to much but it was the best money I have spent on this car yet. Now that it is running good time to spend even more and upgrade the stereo.

 

Buy a big jug (20--24 oz) of Techron at most any auto parts house, pour it in a 1/2 empty gas tank JUST BEFORE YOU fill the tank. Drive until the tank is less than 1/4 full...and "Wallah!" cleaned injectors.

 

So I have pretty much decided to clean my TBI. I am buying the injectors and gasket kit from eBay. I just hope it is as easy as it looks and everyone makes it out to be. I have allready replaced the TPS should I replace the idel air valve just because? Is there anything special I should do or watch out for? Are the shaft bushings a problem? Should I put a spacer under it while I am at it or is that just a waist of money. My car is completly stock. Is there anything else that I sould do to improve the relieability and gas mileage? I know the engine is tired but I need it to last a little longer. I have spent alot of money on this car now I would like to just enjoy it driving with the top down not worrying if it is going to make it home.

 

One tip I can give is when you rebuild it, make sure all o-rings are sitting straight in the injector pod and definetly in the fuel line fittings, or it will leak and tightening things to stop it will just break everything, and it's very easy to cross thread the fuel fittings into the injector pods, so be careful of that

 

witchunter can clean and flow test injectors no need for new ones . that is unless the pintles are worn out .

 

Well the rebuild went great. My milage increased quite a bit. But now I have a Vortec 350 330Hp with a GMPerformance alu. smog intake and was wondering what I should do about the TBI? Should I just put 350 injectors in it? Should I just buy a whole TBI for a 350? What about 454 injectors? What about getting a Holley? Please give some input I just at an inpass and don't know the best rout to take.

 

With 330hp I would use a 7.4L TBI with 75 lb injectors(#2560) @ 20 lbs FP. supports 350 HP. Will require tuning. Watch the DC%. Keep in under 85%.

 

How do I get 20#s fp?

 

1. Start with a fuel pump capable of 25+ psi. The Delco EP241 is often recommended, as are various high-output Walbro pumps.

2. Add a stiffer spring to the fuel pressure regulator in the TBI unit, and adjust as needed.

 

I too use the Aero FPR as illustrated. Comes with 2 springs one 10-20 and another 20-50. Issue is the cost I recall about $125. Others are available. I think Kirban is another MFG. I would look at EBay for options at least. Issue is finding one suitable for higher pressure TBI. If you opt to make stocker adjustable by modding a source for one step higher than stock is topdownsolutions for spring. 15$ ?

 

What about a TBI from a Caprice with the cop car motor in it? Who makes a spring that is calibrated for 20 pounds or what ever you tell me I need. My TBI is fresh can't I just put 454 injectors in it, or even injectors from a 350.

 

Try it and see.

Try topdownsolutions as recommended above, or go to a hardware store with the original spring in your hand.

Match up a spring from the hardware store that has the same diameter and about the same length, but is just a little stiffer. Adjust your TBI regulator to suit.

Sure, you can put in different injectors. Doesn't mean you'll get the right fuel curve. 454 injectors might give you the fuel you need for full power, but I bet they're pig-rich at idle.

 

TB units come in two sizes 305-350 and 454. There is an assortment of injector sizes 45-85. Go to turbo City website and find out what they can offer on springs as well.

Aeromotive may have an assortment of springs as well. I run their 20-60 lb spring.

 

True to a point. the ECU drops PW and flips from synch to asynch fueling and idle gets funky. Solutions exist. Best of two is to use a VAFPR.