Injector noise

[DANZIGS]

Well I finally got some time to play with the caprice this weekend and did the TBI mod that I have been wanting to do for some time. I put a 3/4 inch spacer between the TBI and intake manifold, 3/4inch because it was homemade. I also made the stock fuel pressure regulator adjustable. Put it back together, took it for a ride and WOW. What a difference in response. There is a problem though, at least I think. It seems the injectors are clacking louder now, but again I never payed any attention before when I had the air cleaner assembly removed. Or is it possible the fuel pressure is set too high? I do not have an in line gauge or fitting to read the pressure. TBI on this year (89) did not have a shrader valve. Any ideas or is it possibly normal? I know with certain vehicles you need a screw driver to place against the injector body and your ear at the other end to hear it. This I can hear standing back from the motor with the air cleaner removed.

[CD Smalley]

Sounds like the pressure is way up. You need to get a guage on there to see what you're getting and quick.

[DANZIGS]

Am I putting the gauge on the inlet or the return line? It's more of a slight grrrrrr noise not a clacking noise like previously stated. Sorry for any confusion.

[CD Smalley]

Gauge needs to be on the inlet side. The TBI injectors can take more pressure than the TBI pump can deliver. My 89, with the VaAFPR, will spike to 25psi when the vacuum drops.

[DANZIGS]

By putting it on the inlet side wouldn't it be reading the pump pressure and not the pressure from the regulator? Besides the noise from the injectors, you say it should be able to handle the pressure though? I just don't want them to fail when I'm 20 miles from home. I'll be installing the gauge asap regardless just to know where I'm at pressure wise. The car is running so much stronger now. It continues to pull right to the shift points now. I like the little 305 again.

[DANZIGS]

Ok, I picked up an inline pressure gauge for 15 bucks at autozone and installed it on the inlet side. I was getting 11.5 pounds and I cranked the regulator to the max of 12.5 pounds ( it's the stock regulator). I was getting 10 pounds stock, and I would like 13.5 but throttle response is awesome now. The injector noise is a little louder but the sound is contained with the airlid back on. This mod only cost me the price of the fuel pressure gauge! I cut my own gaskets with material from work and made the spacer out of the same thick high strength plastic they make thresholds out of at ice rinks ( I work at one too). Thanks for the info CD Smalley.

[CD Smalley]

Pics please!!!!

[DANZIGS]

Just give me time. The digital camera is getting fixed and my cellphone camera sucks. I'll post picks of the regulator and how to modify it, along with the spacer. Thanks again for the gauge info.

[DANZIGS]

Hopefully this helps for now until I get the pics up. I used several websites to aid in the regulator modification, some more detailed than others. Be patient with me because I'm not that computer savy. I really don't know how to add a link, no laughing . I typed in yahoo search engine, MODIFYING GM TBI, TBI FUEL PRESSURE REGULATOR etc, be creative in your search entrys and you will you see several listings of how to mod your own or purchase aftermarkets that will include pics. Modifying the regulator was really simple. Once removed you will see the spot weld in the bottom of the regulator bowl where you will need to drill out. Once drilled, the cup inside the bowl will fall out and you will be able to see how the screw turns. Just don't push hard with the drill. You cut a notch in the screw so you can turn it with a standard screwdriver once reassembled. Counterclockwise to raise pressure and clockwise to lower. I made a mark on the side of the bowl where you see the set tab for a refernece where it was located to start with. Plus once I reassembled the bowl back on the injector pod, I turned it so you can see the set tab when the TBI is back on the car. Mine is now cranked all the way up. To remove the regulator, you need to remove the top injector pod. I had the whole TBI removed to do this because I was adding the spacer plus it's a lot easier than doing this on the car. The online sites that I referenced said the gasket can be reused but noway with mine being 19 years old. I saved it the best I could and traced it out on gasket material (not the real thin stuff, this was almost like real thin cardboard which would allow some compression). I then coated the material with permatex spray copper gasket sealer which is gas resistent. For the gauge, Autozone sells a gauge that splices in the line for 15 bucks in their performance section. It says not for fuel injection but with a TBI you won't exceed the psi limit (15psi). Like CD Smalley said, install it in the inlet line not the return. I spliced in along side the valve cover where the line was straight and unobstructed. For the spacer I used the TBI mount gasket and traced it out on the plastic I had, then jigsawed it out. I drilled the 3 bolt holes out and the bores were done on a drill press with a 44mm bore bit. The cutter used for door knob holes and such. The bores on the throttle body are actually 43mm but 44mm was as close that I had. I got 1 inch longer bolts and traced another TBI gasket out. That gasket I did not coat with anything because it was not under pressure like the injector pod gasket. I've always had a dropped 14" open element air cleaner on the TBI so with a 3/4 inch TBI to air cleaner housing spacer (purchased from Autozone) and the stock housing spacer the air lid will clear the hood. The plastic used for the spacer is actually 5/8 inch thick and with the gaskets the stock linkage bracket will work fine without any modification. I just had to readjust the TV cable slightly. Fuel lines connected back up with a little finnagling. I also cut a standard screwdriver shaft about 2 maybe 2 1/2 inches long to adjust the regulator with the TBI on the car. Not real easy to turn on the car but I got the feel for it now. You maybe able to replace the regulator screw with a longer one but it is a hard to find thread at that size, being 2 1/2 inches long. It's an M6 with a .75 fine thread. .75 fine thread is the hard to find M6. Plus you would still have to modify the screw part in the regulator housing because the factory one has a welded on washer to ride on the cup surface. Again I will get pics up but I hope this helps for now. Check it out. It was definitley worth doing. Like I said before, my car was getting 10psi , and from what I've read these motors, 305 or 350 like 13 psi. It pulls a lot harder now.