Better explanation of LB9 TPI problem

I've run out of ideas how to get a truck running correctly.  Its a 1982 Chevy pickup with a 1990-92 LB9 305 TPI engine.

It ran at one time as I've seen it driving but I bought it not running. They put in / removed some fancy alarm/remote start system and it never ran after that. After much trouble shooting I found the VATS bypass was labeled / installed  incorrectly. After I corrected that the engine started but would only idle. The fuel psi at the pump is 50-60. After I put a new diaphragm in the regulator I get around 40psi at the fuel rail engine not running.  At idle psi is 35-40 and goes up a little to 45 psi as revs go up(when I can get the revs to go up). I put on a new MAP sensor. The TPS tested good. I've checked for vacuum leaks.

After I rebuilt the fuel regulator the engine does run better. It now will run above idle if I very slowly open the throttle. There is just no power, if I open the throttle fast it boggs down and dies. Sometimes after it runs it won't start again for a few minutes. There doesn't seem to be any pattern to this, Hot or cold doesn't matter. As far as I can tell the ignition system seems ok. The manual I have does not say what the timing is set to. I have it set at 4 BTDC for now. That is with the timing adjust (TAN/BLK) wire disconnected.

I'm running out of things to check / replace. The ECM is a 7730 and it has a Hypertech sticker on it. The ECM itself is a remanufactured  Cardone ECM.

I'm guessing the engine is a 90-92 because it has a serpentine belt drive and alternator on the drivers side, has a MAP instead of a MAFS  and the ECM is a 7730. The last two are for 90-92 models as far as I can tell.

As I said I'm out of ideas. I have a higher PSI fuel pump 60-80psi, the one that came on the truck, and I'll put it back on today but I don't think that's the problem (I didn't have a fuel psi test gage before I bought the new pump, wasted $120 I think on the new pump).

Does anyone have any ideas?

Thank you
Doug  

copy and paste this link...

http://www.fastbird93.com/Diagnostics.htm

the lower right corner has the gm no start diagnostics...   everything is the same except for the ignition system..

check your messages above when logged in...  

Ok, checked the injector ohms. one was 2.9, one was 6 and another was 9.7. the rest were 14-16 ohms...could this be the problem?????

I hate to spend a few $100 if its not the problem. if it is what injectors to buy. It has full headers and a hypertech prom.

If a set of injectors is +500 then I'm going to revert to a carb.

Thanks
doug  

i grabbed this from another thread .... you will have to open the IMAGE in a new window to read all of it...

its an image.. not text... i think it might help....

 

oh.. this is what the bottom of the injector looks like...




this is a standard brand... FJ713....     but NOT a standard FJ713X


i have not found the bosch number yet....  

waynep7122,

Thanks, well I read this after I ordered a set of bosh III's from southbay. The post said the remans are junk but I've read good things here about FIC and Southbay. Really I have no choice since I can't afford new ones. Can't be worse that what I have.

I'll be really lost if this is not the final problem. Each thing I've done has helped a little (except the MAP) and I'm hoping this is the last thing. While I have it all apart I think I may as well replace the EGR just for the hell of it.  

Well I put in the new Bosch III's and it solved the problem. I think I had many problems and this was just the last fix. On a side note, I had to use the top 0-rings from the old injectors to keep them leaking from the fuel rail. The old ones are .01- .02" bigger. I'm not saying the wrong ones came with the injectors, it could be the fuel rail. I tried to look up the part number to be shure what year it was from but it doesn't match any PN I could find. 17083347 is stamped on the fuel rail.

Thanks to all
Doug  

Just want to give a big thanks to Wayne for all his help. It would have taken much longer if not for his help

Doug