TBI Conversion Build

[big dump]

Well, the return T I bought didn't work out. It was too big of a diameter and didn't fit right, so I built my own.





I used 1.5", .120 wall aluminum. I had some friends of mine at the local hot rod shop bend it up for me in a few sections. Then I just cut it and taped it into place, fit and tested it twice, then removed and welded up. My aluminum welding isn't all that great, but it did the job, and didn't leak.

Got the rest of everything mounted up and connected, had a friend to help me with the wiring, while I plumbed the fuel lines and mounted the fuel pump.



I mounted the fuel pump underneath to the floor board because it was a nice open area away from everything. The power wire from the ECM to the fuel pump was run mostly inside the cab under the carpet, and then droped out right about at the rear wheels. I tied it into the frame rail and went up and over to the pump.



Finished all the connections and mounted the coil and map sensor up where they would clear the air cleaner.



Put the fuse in for the ECM and powered up the fuel pump in cycles to prime it. Fired up after cranking a few times. Seemed to run strong on initial startup, however after I timed it, I'm getting a surging idle, and it stumbles under load. I have a few ideas that I'm going to troubleshoot, and hopefully will be able to get the kinks worked out and get it back on the road.

First, I think that I may need to lower the fuel pump, as it is sitting above the level of the gas tank. After reading some posts on thirdgen.org, electric fuel pumps run best if mounted below the level of the outlet on the gas tank. Secondly, I may need to adjust the throttle plates on the TBI unit itself. The IAC is supposed to control the idle but the counts may be too high because of the throttle plates. Those are the only two issues I can see at this point. If any of you guys have experience with this, now would be the time to chime in. Any help is appreciated.

Thanks in advance.

[djracer]

with the tbi trucks I have played with I ran as much timing as it would take without pinging! they would not run timed to spec.

[manimal]

[QUOTE=big dump;2473780]Well, the return T I bought didn't work out. It was too big of a diameter and didn't fit right, so I built my own.





I used 1.5", .120 wall aluminum. I had some friends of mine at the local hot rod shop bend it up for me in a few sections. Then I just cut it and taped it into place, fit and tested it twice, then removed and welded up. My aluminum welding isn't all that great, but it did the job, and didn't leak.
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I am not understanding this set-up. Won't the gas from the return and filler collect in the tube and overflow?
-Lance

[Rust Buster]

Not sure if you already have this covered, but I couldn't tell from the pic, you'll also need a filter before the pump and after it. They are very sensitive to particles so you'll need a pre and post filter. I don't understand the return line either.

[big dump]

Sorry, I should have been more detailed. There is a 90° bend in the 3/8" inlet tube that extends beyond the arc and points down towards the tank.

[big dump]

And yes, there are filters in line. I'm still not sure that it is pumping correctly though, being that I mounted it above the fuel level. I plan on lowering it to see if it helps.

[watahyahknow]

Originally Posted by big dump

And yes, there are filters in line. I'm still not sure that it is pumping correctly though, being that I mounted it above the fuel level. I plan on lowering it to see if it helps.

that would bring the pressure up a little

[big dump]

Haven't had much time to post with the holidays, however, I got it all up and running with a couple of codes to trouble shoot. First I was getting a lean code, so I bumped the fuel pressure up with an adjustable fuel pressure regulator from Arizona TPI.

Link: http://www.aztpi.com/product.php?pro...&cat=10&page=1

That seemed to help for a day or so, then I started getting a rich code '45' at idle. I spoke with the guys at AZTPI about it and I may need to do some advanced programming to adjust the fuel curves in the ECM because my motor wants more fuel under load, but is getting too much at idle. For the meantime, I dropped the fuel pressure slightly, and it seems to be running really good around town. I also had another code pop up for low voltage at the TPS code '22'. I threw another TPS at it for $35.00, and that went away.

Overall, it's been running much better than with the carb. I think that for my engine, I need to do some more programming to get all the potential power out of it I can, however, for around town, it's running really good. I'll have to post on the difference in fuel economy once I run a couple of tanks through it.

What did I learn? A lot about the vehicle, and a ton about TBI systems in general. Also that it definately pays to take your time and try not to get frustrated, if you do, move on to another part of the project for a while and come back to what frustrated you with a clear head.

What would I do differently? I would probably only buy all the components off of a vehicle that I took them off of myself from a yard or donor vehicle. Donor vehicle would be the best. When the OE parts arrived that I bought from another member online, they came two weeks late, in a box that USPS re-packed and had a huge damaged sticker on it. When I opened it up, it was packed very poorly and many of the connectors were broken on the harness, and one on the distributor. This really forced me to buy a new harness, and some connectors that I could have avoided otherwise. I would also make sure to acquire all the parts I could up front so that I wasn't waiting on parts/returns in the mail.

Make a good comprehensive list, and check off as you go along. Make sure you also have another set of eyes to check you periodically, I was fortunate to have a good friend go over my work before fire up, and it fired right up because he caught a couple things I had missed. If you have the opportunity to have a chip burned locally to fit your motor, go that route. I did the mail order thing and will probably have to go back in the future and have one burned for my motor with the shop having my motor on their scanner so they can read all the information and make it perfect. There's only so much you can do online without the person doing the programming having your motor right there in front of them.

GROUNDS and VACUUM! Make sure you double check all your grounds and vacuum lines. A weak ground or a small vacuum leak can cause a HUGE headache on a tbi setup. Make sure you try to have some fun with this kind of project and work with a buddy if you have some favors saved up. It makes all the cuts, bruises and headaches much easier to deal with.

Anyone feel free to P.M. me with questions or comments.