Thought i'd give TBI a try on the ole 2f

[Sputnik40]

Nice write up. Will have someplace to go when mine breaks down someday. I have the same ICU out of an astrovan - but as I bought it secondhand don't recollect all the details - but was told it was reprogrammed?

If not fuel pressure - did you adjust the timing with the proper wires disconnected so as to give you non advanced conditions?

Mine seems to idle a tad high sometimes - but I've never complained with the fuel economy I get and fact that it just chugs uphill all day long...

 

[badass]

troll, ya i am using the stock retun metal lines, this is probably an issue, i will do what you said, how hard was it to drill out the tbi to access the idle speed screw, what size drill bit did you used, any tips??

Also, wll changing the 5/16 return line help with idle as well or solve rich running?

What did you do to fix your rich running, i would think the computer would automatically adjust the fuel mixture.

 

[badass]

I'm under the impression you don't have a fuel pressure guage? If so do this.

Take the fuel return line off and put the hose into a bucket. See if it runs better. Most likely if you try to use the metal fuel return line back to the tank it is not big enough to flow enough fuel back to the tank and it backs up. Just make sure you watch the bucket. That fule pump flows a lot of fuel. It will fill the bucket up in no time. If the restriction is the problem just run 5/16 hose from the TB back to the tank.

If this works you will need to buy a t-fitting and run the line into the fuel filler overflow line. NAPA has the fitting.

If you have a fuel pressure gauge check the inlet fuel pressure. Should be around 12-15psi. With a restriction in the return it will get up to 20-30psi. Not good.

also troll forgot to say that i think my downey kit came with a t fitting, but i'm not clear on what your saying i am supposed for?? can you clarify.

 

[badass]

Nice write up. Will have someplace to go when mine breaks down someday. I have the same ICU out of an astrovan - but as I bought it secondhand don't recollect all the details - but was told it was reprogrammed?

If not fuel pressure - did you adjust the timing with the proper wires disconnected so as to give you non advanced conditions?

Mine seems to idle a tad high sometimes - but I've never complained with the fuel economy I get and fact that it just chugs uphill all day long...

i havent played with timing yet really, just sorta eye balled it and set it to where i think is right for now. I'm not sure what wires i'm supposed to disconnect for setting timing.

 

[Trollhole]

troll, ya i am using the stock retun metal lines, this is probably an issue, i will do what you said, how hard was it to drill out the tbi to access the idle speed screw, what size drill bit did you used, any tips??

Also, wll changing the 5/16 return line help with idle as well or solve rich running?

What did you do to fix your rich running, i would think the computer would automatically adjust the fuel mixture.

That plug sucks getting out. Be prepared to throw crap. DOn't even think about doing it on the truck. I drilled a small hole. 1/8 and worked my way up. at 1/4 you shoud be able to see exactly what you should and shouldn't be drilling. You just need to make a hole in the cap and not screw up the torx screw underneath. Personally I'd drill a big enough hole to get the torx bit in there and leave the rest of the plug. A dremel tool works wonders finishing getting the plug out.


Well once you have pulled the return off and run it in a bucket or if you have a long enough hole back in through the gas filler and tested it to make sure this is the problem then yes I'd run 5/15 all the way back. Worked for me. It solved my rich idle issues.

Computer can only do so much.

 

[badass]

That plug sucks getting out. Be prepared to throw crap. DOn't even think about doing it on the truck. I drilled a small hole. 1/8 and worked my way up. at 1/4 you shoud be able to see exactly what you should and shouldn't be drilling. You just need to make a hole in the cap and not screw up the torx screw underneath. Personally I'd drill a big enough hole to get the torx bit in there and leave the rest of the plug. A dremel tool works wonders finishing getting the plug out.


Well once you have pulled the return off and run it in a bucket or if you have a long enough hole back in through the gas filler and tested it to make sure this is the problem then yes I'd run 5/15 all the way back. Worked for me. It solved my rich idle issues.

Computer can only do so much.

alright troll sounds good, so now i'm pretty sure that should solve the rich running, and now i know how to fix the idle adjustment. Can't do much right now, got a cal test tomorrow, and classes won't end till 730 so next update will probably be wednesday my off day. Later and thanks man, really helping me out.

 

[badass]

Also, forgot to ask, troll my cold start is not working, so no high idle, and she won't crank and idle without my help, so is that becasue i need to adjust the idle screw??

How about the cold start, why is it not idling at 1200 rpms like it is supposed to??

 

[Trollhole]

Also, forgot to ask, troll my cold start is not working, so no high idle, and she won't crank and idle without my help, so is that becasue i need to adjust the idle screw??

How about the cold start, why is it not idling at 1200 rpms like it is supposed to??

Aint gonna idle with it shooting twice the amount of fuel it needs down the TB. One thing at a time. Check fuel return issue first.

Did you hook the wire to the starter so the computer knows when to add the enrichment?

 

[badass]

Aint gonna idle with it shooting twice the amount of fuel it needs down the TB. One thing at a time. Check fuel return issue first.

Did you hook the wire to the starter so the computer knows when to add the enrichment?

well i won't be home till later tonight so haven't touched it yet, but i'm going to do the return line as soon as i get home, do you think 5/16 is sufficient or should i go bigger?
Also how did you get the 5/16 to go into the tank? Was the fitting on the tank the right size?

Regarding the purple wire (from the gm harness) that is supposed to hook to the starter, which wire is it supposed to hook up to on the starter? Is it the black and white wire (toyota harness) that only gets power in starting mode?

Does hooking up that wire actually affect the idle speed during cold start?

 

[malcb]

Also how did you get the 5/16 to go into the tank? Was the fitting on the tank the right size?

I was interested in the return problem, I can see it being an issue in the future and wondered were the 5/16 pipe could go but the answer was in Trollhole's post and it's clever. Post 40.

"If the restriction is the problem just run 5/16 hose from the TB back to the tank.
If this works you will need to buy a t-fitting and run the line into the fuel filler overflow line. NAPA has the fitting."

I think that will save me some time and trouble.

 

[badass]

the downey kit came with a t fitting, so basically run a 5/16 line back to the tank, utilizing the t fitting, run one line to the tank and another to the fuel filler overflow line. Right??? Now i haven't looked at the tank yet, but is there a spot to plug the line into the fuel filler overflow line or do i need to tap into it.

 

[too tall]

i havent played with timing yet really, just sorta eye balled it and set it to where i think is right for now. I'm not sure what wires i'm supposed to disconnect for setting timing.

You disconnect the tan w/black stripe to set the timing . I agree with the return line maybe being the problem with running rich. I ran new feed and return lines when I did mine . The computer does need a little run time to calibrate so running it after you set the timing (at temperature) is a good idea. good luck .

 

[Trollhole]

well i won't be home till later tonight so haven't touched it yet, but i'm going to do the return line as soon as i get home, do you think 5/16 is sufficient or should i go bigger?
Also how did you get the 5/16 to go into the tank? Was the fitting on the tank the right size?

Regarding the purple wire (from the gm harness) that is supposed to hook to the starter, which wire is it supposed to hook up to on the starter? Is it the black and white wire (toyota harness) that only gets power in starting mode?

Does hooking up that wire actually affect the idle speed during cold start?

5/16 is fine. I have seen two TBI systems connected the same way and both acted different with the return line. My system uses a crappy poly tank. The barb fitting at the tank was just to small to use. Granted it accepted a 5/16 line the barb opening was really small. AT first I thought I could still use the stock hard return line so I just plumbed the barb fitting out and used a t fitting for the fuel overflow hose going to the fuel filler tube. Still had an issue, wasn't as bad but my fuel pressure was over 15psi at idle. SO I decided to run a continuous piece all the way from the TB to the tank for return. Worked great.

Yes the wire only needs power when starting. It's what tells the computer to add extra fuel. Don't hook this up to a constant 12v as the computer will think your an idiot and just keep adding more fuel than what is necessary.

 

[Sputnik40]

Wow - the more I follow the problem discussions the more I understand....

If I recollect correctly, you need to disconnect the brown wire that runs to the distributer in order to set proper timing (this disconnects the computer from advancing the dizzy). Not sure how well setting the timing would work with all the other problems - but it won't run right if not set closer that eyeball to correct. I'd give it a shot and set in the low to mid teens.

I think I'm still using some of the metal return lines - will have to look. Same plugs for the last several years - and it doesn't run rich?

 

[Trollhole]

Wow - the more I follow the problem discussions the more I understand....

If I recollect correctly, you need to disconnect the brown wire that runs to the distributer in order to set proper timing (this disconnects the computer from advancing the dizzy). Not sure how well setting the timing would work with all the other problems - but it won't run right if not set closer that eyeball to correct. I'd give it a shot and set in the low to mid teens.

I think I'm still using some of the metal return lines - will have to look. Same plugs for the last several years - and it doesn't run rich?

Bill I think a lot of it has to do with the fuel pump and what kind you have. Also return lines on an old cruiser can be a pain. Especially if it had a Weber prior and the PO didn't cap the line off and it filled with mud.

I'm still amazed at how much fuel comes out of that return line.

 

[badass]

Bill I think a lot of it has to do with the fuel pump and what kind you have. Also return lines on an old cruiser can be a pain. Especially if it had a Weber prior and the PO didn't cap the line off and it filled with mud.

I'm still amazed at how much fuel comes out of that return line.

Troll, i just ran the return hose straight into 2 gallon tank, and dam that son of a bitch filled up fast, but no more clouds of black smoke, only when i first started her up but nothing like before, night and day difference. Doesn't smell like she's running rich at all. However i still have no idle, and no COLD START HIGH IDLE, so i think drilling the tbi will be a must.

Otherwise, she runs extremely smooth, amazing throttle response, very happy so far!!!

Any ideas on the no high idle with cold start, also she's throwing one code, 43, ESC module not receiving knock sensor signal, the knock sensor is hooked up though.

Thanks man, great help so far!!

 

[Trollhole]

I'm not sure about the ESC module. I don't have one. My knock sensor wire comes straight out of the ECU. Not that mine is hooked up. lol.

You might also try resetting your AIC. Generally it controls the air going into the TB at idle. It could be bad or not wired up correctly. Recheck you connections. I would think Jim @ Downey would have instructions for resetting it.

It's not going to hurt though to drill out the plug and crank the idle up a bit. You don't want to rely on this for your idle control though. Those butterflies are conneted to the throttle position sensor which sends a signal to the ECU. The ECU is not gonna like thinking it's open all the time.

 

[badass]

Troll, i drilled the hole out and can have it hold a idle but don't like doing it this way...

Something is definetely wrong with my cold start idle, i will look into that. However, even if the cold start doesn't function, shouldn't it at lease IDLE at normal rpms??

How did you get yours to idle normally? were you able to achieve a good idle with the stock gm prom? Thanks.

 

[badass]

Troll or anyone, can someone post a pic of how the cable linkage for the gas pedal works??? I am having a hell of a time trying to figure out how the dam thing hooks up correctly. I am using the downey gas pedal.

 

[Rocky_LC]

BA -

How much would you estimate the whole shootin' match will cost - in both $ and time?

Thanks -

Rocky