love-my-V8-280Z Posted September 28, 2004 Author Share Posted September 28, 2004 Thanks, I have the Helms owners manual, and did not see where the oil pressure unit hooks up, and I don't think the PCM sees the fuel pressure. If you find I'm wrong you will have solved my problem. I'm thinking I have optispark problems, what do u think about this aveune? Also the fuel pump does not come on when I'm hoding the key.... Terry Quote Link to comment Share on other sites More sharing options...
80LS1T Posted September 29, 2004 Share Posted September 29, 2004 Ok heres a few things you should check.... Connector A on PCM... *Grounds at A18 & A2 good? Connector B on PCM..... *Battery+ @ B15 *Ignition Feed +12V key on @ B30 Connector C on PCM...... * Ground @ C32 Connector D on PCM..... *D1 Engine Ground *D3 Ignition Feed +12V key on These were all suggested as a possible "cranks but does not start" possible causes by ALLDATA. Especially the connector A because that is where your injector controll circuits are wired to. Now your fuel pump should turn on when cranking. I can not find the Oil pressure sensor wired into the PCM either. However I think once the engine starts to crank it switchs from the Fuel Pump relay to the 12V beingn supplied through the oil pressure switch. The switch will not close until there is 4 PSI on it. Heres what I suggest doing. Apply +12V to the #87 pin on the fuel pump relay. This is how the wiring diagram shows it. This will bypass the relay and act as if the oil pressure switch is closed. Guy PS not getting to frusterated yet are you! Quote Link to comment Share on other sites More sharing options...
love-my-V8-280Z Posted September 29, 2004 Author Share Posted September 29, 2004 Guy, Your awesome! I thank you for your help. But after all that you just did for me I have more data. As I had said I have checked the injector ground, to ground using my continuity tester. Well guess what, I borrowed a gizmo that plugs into the fuel injector plug and blinks... Well it was blinking.. So the digital continuity tester doesn’t work for this application. Second I borrowed his fuel pressure gauge, and it showed I have low fuel pressure, by turning the key on and off I got it up to were it belonged.. Did not always hold,,, SO. Anyway I have hooked the fuel pump relay to the computer, and supplied it with switched power only..... I need to change that! Ok, one you talked about ALLDATA, I'm impressed that they provided data on what wires should have power etc.. but $25 a yr is a lot, once would be cool, but in a couple years that adds up.. Back to my problem, The car sorta starts now that I can see the fuel pressure and mess with the key until its good and pressurized... But it bangs and pops real bad.. Shoots fire out the headers.. I did check the wires and the optispark pictures to confirm that I could not have put it in wrong.. Even thou that’s the directions I'm thinking now... I'm sorry for giving you bad data, no one told me I could not count on my digital meter to check a fuel injector ground. I'm going to go and check my plug wires once more tonight quick make sure I have the optispark orientation correct... Please give me your email address, I have been working on a wiring diagram you may like... Quote Link to comment Share on other sites More sharing options...
80LS1T Posted September 30, 2004 Share Posted September 30, 2004 Since spammers can get email address through posts(I have heard this anyways) I have not been posting my email address in my posts but my email address listed under my name(the email button) is correct. Does the motor run at all now? If so does it just idle rough or does it stall out? Now what kind of pressure are you getting at the rail? You should have about 45-50psi. Mine runs at 47psi.FUEL SYSTEM PRESSURE Ignition ON Engine OFF 284-325 kPa (41-47 psi) With Regulator Vacuum Applied [1] 3.0 - 10.0 psi less than Ignition ON Engine OFF REMARKS: [1] May be checked with either of the following methods. With Pressure Regulator Vacuum Line Attached at normal idle speed. Ignition ON Engine OFF with 10 Inches Of Vacuum Applied To The Pressure Regulator. Now you may have fouled your plugs from all those times trying to start it. Make sure they are good and clean before you get too far into diagnosing anything else. It is impossible to install the 95' optispark wrong. It is keyed so you cant screw it up. Now you could have wires crossed. Heres a pic of the firing order... You could also make sure all your injectors are internally ok as far as wiring. For injectors that are shorted internally. Compare injector resistance to one another. Injector resistance should be within 1.0 ohm of each other. I beleieve they are about 14 ohms. Make sure your IAC motor is ok too. Idle Air Control (IAC) Reset Procedure To reset Idle Air Control (IAC) valve. Depress the accelerator pedal slightly. Start and run the engine for five seconds. Turn the ignition "OFF" for ten seconds. Restart the engine and check for proper idle operation. Guy Quote Link to comment Share on other sites More sharing options...
love-my-V8-280Z Posted September 30, 2004 Author Share Posted September 30, 2004 I will get out and check my injectors tomorrow, I checked the plugs with your diagram and they are correct, as for the IAC I dont think I have one.... Quote Link to comment Share on other sites More sharing options...
80LS1T Posted September 30, 2004 Share Posted September 30, 2004 You should have an IAC. It is located on the throttle body on the passenger side. It has 4 wires going to it. If you need a pic let me know. Guy Quote Link to comment Share on other sites More sharing options...
love-my-V8-280Z Posted October 11, 2004 Author Share Posted October 11, 2004 Guy, I did it! as soon as I reinstalled the Optispark it fired in 2 cranks! A dam nice design these LT1's. Anyway don't put to much effort into this, but it runs for a few sec's and quites. I don't here the fuel pump running and with out any looking I think its the problem, I do not have the radiatior hooked up, do you think the PCM knows this? thanks for your help., I'm not going to put to much effort into figureing it out until I get water to it... But I'm sure glad I have hearing it run behind me.. the rest shoud be easy. One more question, I read somewhere that sheilding the hot wires around the PCM is important. what do you think? I have a mess of wires all around the PCM, its a tight fit under the hood. Quote Link to comment Share on other sites More sharing options...
80LS1T Posted October 11, 2004 Share Posted October 11, 2004 Glad to hear you got it running! No the PCM doesnt know if there is coolant in the system. Obviously you dont want to run it very long with out coolant though because it will get hot really fast without coolant in the system. I would bet that your fuel pump is not staying on and just burning up that fuel that is supplied when you first turn the ket to the run position. You need to figure out why the pump doesnt stay on in the run position. I think it probably has to do with how you have your fuel pump wired to teh PCM. Did you ever try running a hot wire to the fuel pump to see if your engine would stay running? Guy Quote Link to comment Share on other sites More sharing options...
love-my-V8-280Z Posted October 11, 2004 Author Share Posted October 11, 2004 Your right, your idea has helped me, I did some mods to the datsun wiring and have the computer ground the datsun fuel pump relay, so when you sudjested constant power it made me think, I bet I over looked something and the fuel pump relay is not closing when it should be. did you sheild any of your wiring? Quote Link to comment Share on other sites More sharing options...
80LS1T Posted October 11, 2004 Share Posted October 11, 2004 What do you mean by "sheild"? I have that black wire loom stuff over all of the wiring? My PCM is currently being relocated to the inside of the car by the passenger side firewall area. The thick part of the wire loom that goes to the computer is covered actually with a sump pump hose that looks like regular wire loom covering but its just bigger. It is the only stuff that I could find that was big enough to cover that much wire. It's working out great and it doesnt look funny either, it just looks like regular wire loom covering. Guy Quote Link to comment Share on other sites More sharing options...
love-my-V8-280Z Posted October 11, 2004 Author Share Posted October 11, 2004 I read that eletromagnite interferance could cause PCM problems and that you should shield the wire that supply the pcm with power so it dont act up. Sound like you did not and it is not necessary.... That removes one concern... Quote Link to comment Share on other sites More sharing options...
Badass Lt1 Posted February 23, 2016 Share Posted February 23, 2016 #1. Flooring the gas or holding the throttle plate all the way open on a fuel injected engine will turn off the injectors.What is your TPS voltage when the throttle is fully closed, engine off. It should be at about .5 and no less than .23V or it will set a code. When I installed the my 58MM Holley TB I had to round out the holes on my TPS sensor to get it back down to .3V so that it would stop setting the Code 21(TPS too High).Heres what I suggest. Go to www.alldatadiy.com and buy a subscription for a 1995 Camaro with the 5.7. Its way better than a Haynes and it gives trouble shooting info and lots of pictures. Its $25/year for your first car and $15/year for any car after that or for resubscriptions. IMHO its money well spent. I would have spent way more time screwing around on forums asking questions and not getting the info that I need to get my LT1 running like it should if I hadnt have bought that subscription. Trust me on this one! I could give you the info for a 93' LT1 but the injection system isnt wired the same because the 93' is bank fired and not sequentail fired like yours is.Guy M Check the basics: Plug wires routed correctly and not arcing or in bad condition (LT1s are very sensitive to spark breakdown) Make sure you have fuel pressure (invest in a pressure gauge that screws into the shraeder valve on the rail) If the opti is going out, you will usually have a slight miss at idle and a hesitation under load...it should at least fire unless its completely bad) Check for vacuum leaks. Make sure that all unused ports are plugged, esp. at the throttle body. Try unplugging the MAF, and let the PCM default to speed density. That way if you do have a leak somewhere the PCM can account for the extra air. Tim My name is jamal and I have a 93 firebird formula with a 97 engine wire harness and computer. My question is that my car won't fire and the injectors are not getting ground but getting power can you help? Quote Link to comment Share on other sites More sharing options...
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