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Post Info TOPIC: will not start
77


BARRIE, ONTARIO

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will not start
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also those motors are famous for leaking fuel pressure regulators , they leak a bit of fuel into the intake when running , then when you shut off you lose fuel pressure . Maybe try cycling the key from off to on wait 3 seconds , to off then on , 4 or 5 times , then try cranking it over and see if it starts , but they also used to break the springs on tps an stick in wide open .. 77.

 



-- Edited by 77 on Monday 11th of November 2013 07:41:54 PM

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48chev


ANGUS, ONT

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I have a 87 chev 305 TBI in my 48 chev p/u All new gas lines, fitter it will only start If you put gas down the TBI AS soon as it starts it will run great

 weak pump?



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DaveM


ONTARIO

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-An incorrect TPS signal, or a TPS stuck at wide open throttle  can put it into clear flood mode and the injectors will not fire 'til 400rpm is reached.

-Make sure you have power to the injectors while cranking as well as in run.



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fatchuk


ST MARYS, ONTARIO

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put a fuel presure gage on it and check the presure against the specs..I think they were 9-13 psi on that engine..



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48chev


ANGUS, ONT

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Hey thanks guys now IM a old guy what is TPS I have let the pump run for a min before starting still would not start with out adding gas to[ carb] TBI

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77


BARRIE, ONTARIO

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Oh man , see how the int net can screw you up . ha ha I was thinking tpi set up . Go with Chuks an check the fuel pressure ..77.

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DaveM


ONTARIO

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TPS- throttle position sensor.



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There is a very fine line between “hobby” and “mental illness.”
fatstax


COBOURG, ONT

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TPS reports, watch the movie office space and you will find out



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48chev


ANGUS, ONT

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I was thinking [I do that some times] Could it be the coolant temp sensor?IT has been replaced with a mechanical gauge It will start on its own if motor is warm
T throttle
P position
S sensor
Thanks I looked it up I would love to have the old school Carb motor but to late have to make this work

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fatstax


COBOURG, ONT

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depends if you eliminated the sensor for the computer, there are two temp sensors.  it will run and start with the temp sensor unplugged, you would get an engine lite though.   theres another sensor that detects if its ok to start the engine, this will cause the problem you are having if it wont start but adding fuel will make it start, i dont know what its called though



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v8deuce


OAKVILLE, ONT

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Is this a problem that just started? Or Is this the first time it has been fired up? If it is you may have power to the ecm (computer) with the key on but no power in the start position. Just hook up a volt meter to the terminal that feeds the ecm and turn the key to start and check voltage. 

 

  Randy



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slim


DUNDAS, ONT

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As said there are two temperature unit 1 - for your gauge . 1 for the computer the one for the gauge will only have 1wire the sensor will have 2 you need the sensor for it to operate proper



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48chev


ANGUS, ONT

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v8deuce this is something new The truck ran good up to a week ago The temp sensor is on the front of the motor 2 wires has been removed Could it be turning over to slow ?

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fatchuk


ST MARYS, ONTARIO

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What do you mean two wires have been removed from the temperature sensor ? have they always been removed or did you remove them..The temperature sensor tells the ecm what temp the engine is so it can supply the right amount of fuel...It works as kind of as a choke.. that sensor can cause a over rich condition or a lean mixture ..Kind of hard trouble shooting on line but that sensor should be in line with the ecm..To check the tps you can use an analog volt meter just use a couple of paper clips to back stab the pins and open and close the the throttle to check for a nice clean sweep with no glitch.. do this with key on engine off..should have approx 5v closed and go to under 1v wide open..I am not understanding why the temperature sensor is disconnected..do you think it turns over to slow? put a volt meter on the battery when cranking battery voltage should not drop lower than 10v  can you see any fuel dripping from the injectors at the throttle body when you crank the engine..do you have a DLC to hook up a scan tool I know 87 is OBDI but it still has codes that can be retrieved.



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fatstax


COBOURG, ONT

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rememeber the fuel managment from the ecm doesnt start until after the engine is running, starting the engine is a separate function



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fatchuk


ST MARYS, ONTARIO

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Here is some good reading for you ..I recommend printing this off for future use it has much info that should help you trouble shoot this..

http://www.73-87chevytrucks.com/techinfo/TroubleshootingTBISystems.pdf 



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48chev


ANGUS, ONT

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Hey guys I checked all the wires and vacuum lines cleaned the TBI and injections and with no gas down the carb turn the key and it started I do not know why But it runs Thanks for all your help guys
Fatchuk Thanks for that link I will print it off

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