aftermarket fuel pressure regulator options for TBI

[woody80z28]

Yeah, that's the Camaro bay with a 750 Edelbrock. The carb's days are numbered...going EFI soon. The 600cfm I had choked it to 5" of vacuum at WOT, but the 750 is lazy at lower rpm/throttle. No way to fix that with a carb.

The fuel feed bypasses the regulator and the extra fuel flows through the reg and out the return. That way there are no restrictions in the fuel volume between the pump and carb.

 

[vipergtrdj]

ahh I see. I can't seem to figure out this crappy regulator that I threw in my system. It reads 12-13psi, but it runs like its getting 18-20psi of fuel pressure. The engine is literally flooding itself, nothing but gas smell from the exhaust, Very rough idle as well. but if I turn the regulator so the pressure is around 8-9psi, it runs amazing. I know with the bad o2 sensor it will run a little rough, but this is beyond a bad o2 sensor.

I tapped my fuel pressure gauge sending unit (the one on my pillar mount that I get all my readings from), on the feed line just before it goes into the TBI (about 2ft from the tbi unit). It is the only place I could fit it nicely, I want to clean my engine bay up some. Is this an accurate spot for a gauge reading or do I need one right next to the tbi?

also - what kind of efi system are you going with? I was browsing the EFI options for the TBI earlier today.

12/1/11 UPDATE - So I installed the new CTS, O2 sensor, along with a new transmission mount since I was under there. It still bogs and seems like it wants to stall at idle after its warmed up - but it saves itself. I will get some logs up tomorrow to see what the problem is. I did notice that the stock O2 sensor bung was on the straight pipe just before the cats, and I moved it to the drivers side header (thats were the o2 bung was) when I redid my exhaust. Could that be causing the issue? I did extend the harness for the o2 so the plug reachs and i tested the wires (soldered them together), and it works good.

 

[woody80z28]

I tapped my fuel pressure gauge sending unit (the one on my pillar mount that I get all my readings from), on the feed line just before it goes into the TBI (about 2ft from the tbi unit). It is the only place I could fit it nicely, I want to clean my engine bay up some. Is this an accurate spot for a gauge reading or do I need one right next to the tbi?

Is that elec FP gauge or an isolator? I want to make sure you aren't running a fuel line inside the truck to a mech gauge? That is a BIG no-no. Tapping in to the line 2' before the TBI should still give you an accurate reading...but if 13psi is flooding I'd suspect it is reading wrong.

also - what kind of efi system are you going with? I was browsing the EFI options for the TBI earlier today.

12/1/11 UPDATE - So I installed the new CTS, O2 sensor, along with a new transmission mount since I was under there. It still bogs and seems like it wants to stall at idle after its warmed up - but it saves itself. I will get some logs up tomorrow to see what the problem is. I did notice that the stock O2 sensor bung was on the straight pipe just before the cats, and I moved it to the drivers side header (thats were the o2 bung was) when I redid my exhaust. Could that be causing the issue? I did extend the harness for the o2 so the plug reachs and i tested the wires (soldered them together), and it works good.

Your new o2 location should be fine as long as it is a 3-wire heated o2. If it's a 1-wire it may not be getting hot enough to read correctly.

And I'm making my own DIY EFI setup with an OBD1 ECM and an MPFI intake, rails & throttle body setup from Edelbrock. That gives you the most control.

 

[vipergtrdj]

Is that elec FP gauge or an isolator? I want to make sure you aren't running a fuel line inside the truck to a mech gauge? That is a BIG no-no. Tapping in to the line 2' before the TBI should still give you an accurate reading...but if 13psi is flooding I'd suspect it is reading wrong.



Your new o2 location should be fine as long as it is a 3-wire heated o2. If it's a 1-wire it may not be getting hot enough to read correctly.

And I'm making my own DIY EFI setup with an OBD1 ECM and an MPFI intake, rails & throttle body setup from Edelbrock. That gives you the most control.

The fuel pressure gauge inside the cab is electrical. So no gas line going anywhere but from tank straight to tbi, and back . The o2 I got is a stock replacement 3wire one. I am guessing once I get some logs hopefully can narrow down the possibility. I am also going to swap out the fuel pressure regulator with a Mallory or aero one next week. I wonder if all my problems are related with this regulator - Would running a 15psi spring in the stock housing hurt at all even if it is not tuned 100% with my mods? or would the computer be able to learn and adjust it fine?

The reason I ask about the 15psi spring is because I ordered a gasket kit with everything, for a tbi for this intake and tbi unit I got off eBay. Figured I could do the TBI mods, gasket it, clean it up and make it look nice and start from scratch but figured I could replace the old warn spring inside with a 15psi one for now.
'
I would also be interested in seeing the setup once you get it all together - sounds like its definatly worth doing.

 

[vipergtrdj]

So I was just cruising youtube - and found this video ... http://www.youtube.com/watch?v=5j6kJGSEQFE ..... the truck idles at the beginning and sounds similar to mine. It drops in idle then catches itself before stalling. This one has more mods then me, but idles similar.Starting at 20seconds in you can hear it idling down then up. Is that just normal idling ?

 

[woody80z28]

Mine did that when it was stock, but doesn't do it now. IIRC it did in P and in D so I don't think it had anything to do with the auto...but now it is fine with the 5spd. Might just be a difference in the fuel PSI now that the pump is new and I know the pressure is stable.

I'm still wondering why you dont just convert your stock TBI regulator to be adjustable with a bolt. It costs less than a buck for a bolt if you already have the drill bit and tap to do it, and if you need a heavier spring you can get one for less than $20. I forget exactly how much mine was but it was cheap.

 

[vipergtrdj]

Mine did that when it was stock, but doesn't do it now. IIRC it did in P and in D so I don't think it had anything to do with the auto...but now it is fine with the 5spd. Might just be a difference in the fuel PSI now that the pump is new and I know the pressure is stable.

I'm still wondering why you dont just convert your stock TBI regulator to be adjustable with a bolt. It costs less than a buck for a bolt if you already have the drill bit and tap to do it, and if you need a heavier spring you can get one for less than $20. I forget exactly how much mine was but it was cheap.

I have been thinking about it - and I am just gonna convert it on the TBI unit that I ordered off eBay. For a dollar can't really go wrong. The spring I got adjusts anywhere from 8psi up to 30psi or something. Its from TBIchips. On a non adjustable regulator its around 15psi (depending on regulator condition).

I also got a log from earlier today. It looks like im running super rich at idle (BLMs hover around 90), and top end I am lean. I also noticed that my desired TPS value stays at 1.00, and actual TPS value moves depending on my TPS. Is that normal for the desired TPS value to always be stuck at 1.00?

I have attached the log from tunerpro if anyone is able to take a quick look at it. http://www.mediafire.com/?bfij1w3t0j6w065

I wasn't able to attach it to the forum because it was too big.

Edit - I just realized that I may need to reset the computer before having an accurate log since I never reset it after replacing the oxygen sensor ..... I took it out again a little earlier and the SES light came on, then when i came out of the store to leave it was off again. It was doing this when the old O2 was in, so I think it still has the code stored and hasn't reset itself?

 

[woody80z28]

Desired TPS 1.00 is normal. I'll try to take a look at the log when I get on my other computer. The code will clear itself after 50 key cycles after ot has been fixed.

 

[vipergtrdj]

Desired TPS 1.00 is normal. I'll try to take a look at the log when I get on my other computer. The code will clear itself after 50 key cycles after ot has been fixed.

ok. I wasn't sure if it was 1.00 or not. I had disconnected the battery and all was good afterwards, it seemed to idle better as well. Tomorrow the new TBI unit and rebuild kit come in so I don't think this log is going to help much since I will be using a better fuel pressure regulator (set for a constant 15psi). I won't get around t oinstalling the new TBI unit till Tuesday night. Tomorrow night I am going to clean it all up, and do the ultimate TBI mods to it.

I am going to take some pictures as I progress with the TBI mods.

 

[vipergtrdj]

well I did not get a chance to take pictures since it was dark and rainy outside when I was swapping things over. I did the ultimate TBI mods, and shaved down the tb shafts and all that. I also installed my injector pod spacer, all new gaskets through the entire TBI and new injector screens, and I made the stock regulator adjustable. Now with the regulator screw all the ways out, I am at 7psi for pressure, and with it all the ways in I am at 7psi according to my gauge..... I do have a mechanical gauge that I am thinking about putting in close to the TBI unit, to see what my pressure is. Other then the 7psi the truck feels great to drive. Very responsive compared to before.

I think the mechanical gauge I have is 1/8" NPT, but I would have to check. Is there a fitting I can use to put in a mechanical gauge right next to the TBI unit? Maybe something a parts store would have in stock? I have AN fittings going into the TBI right now, since I have braided lines.