flibuoy Posted March 16, 2005 Share Posted March 16, 2005 This is probably easy for someone: Engine is 94 w/Painless harness, ECM has VATS removed Engine sat over 2 years but was running when donor hit. Cranks and almost starts.....not quite enough of ?, sorta like a cold carbed engine with no choke, acts lean new:complete Delco opti, coil, ICM, wires, plugs test ok: MAP, MAF, TPS, various circuits, fat spark at plugs, noid light OK on all injectors fuel pressure 45#, drops a bit on crank, raises if return blocked no obvious vacuum leaks questioning the IAC which appears very dirty, stuck or stiff. Does the IAC have enough input to prevent the start? No default value for limp home as other sensors? Too lean a mixture can come from not enough pulse width too I imagine, but this should be ECM controlled. Easy way to answer is to get a new IAC but you see list of "new" above that did not answer. $$$ If that isn't fix then ? The list knows I have been ready to finish swap a LONG time, but for the failure to start... John Quote Link to comment Share on other sites More sharing options...
mark Posted March 16, 2005 Share Posted March 16, 2005 Check you power to the ignition system. Make sure you have power when cranking and when key is at the RUN or ON position. I had a similar problem. Had power in the ON position but no power to the ignition when cranking. It would try to start When the key was released from cranking because the ignition system got power just as the motor stopped turning. Also, check the spray pattern on the injectors. Could have a clogged injector that still checks out OK electrically. Hope that helps. Don't give up. You'll figure it out. Mark Quote Link to comment Share on other sites More sharing options...
flibuoy Posted March 17, 2005 Author Share Posted March 17, 2005 solid 12 volts in crank...it trys to start in start position, no change as key released note the injectors are brand new from SLP Quote Link to comment Share on other sites More sharing options...
jbc3 Posted March 17, 2005 Share Posted March 17, 2005 What mod level is your motor? Couple of thoughts off the top of my head... Did you have the motor apart? Cam/Crank position correct? If the motor actually sputters like it's firing, What does the FP do when the motor tries to start? (not just during cranking) What size injectors did you get, did you change the injector size in the program? Try a squirt of gas in the intake and see if it fires. You already checked the spark at the plug so the opti is good. I helped a friend recently that had a similar acting starting problem, but he had a large cam 242/256-109 and 50lb injectors. The engine was actually flooding, so we took a ton of fuel out at start-up to fix the problem. Then changed the oil! Have you pulled any plugs to see if they are wet? I don't think that the IAC will cause the motor not to start... may not idle fine but should start. You said the MAF etc test fine, so I would assume you're sensor fuse is fine. Good luck, Jody Quote Link to comment Share on other sites More sharing options...
flibuoy Posted March 17, 2005 Author Share Posted March 17, 2005 Oh happy days..... Just fired it.....held throttle full open....fired right off....and I had suspected TOO MUCH air! Once it fired it was very smoooth and eased down to near a stable idle, but had to shut off after few seconds since no water in it at all. Pick up lower hose later today I ordered and get water in it and I believe I can lick anything minor that shows up. I feel same about IAC as you noted...may not be good idle quality but should not prevent start....there is possiblity that MAP vacuum source was plugged....there was loose gasket material from old gasket in top of throttle body under the plate...hmmm John Quote Link to comment Share on other sites More sharing options...
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