kbusch18 Posted September 20, 2012 Share Posted September 20, 2012 hey having a problem with my comanche starting fuel pump kicks in when promted then turn key on and will fire up for a slit second and shut off if i leave the key turned it will keep doing this cycle for hours so far i have replaced the ignition switch crank sensor wire is not melted Link to comment Share on other sites More sharing options...
Geonovast Posted September 20, 2012 Share Posted September 20, 2012 Bypass your ballast resistor and see if it still does it. Link to comment Share on other sites More sharing options...
cruiser54 Posted September 20, 2012 Share Posted September 20, 2012 Bypass your ballast resistor and see if it still does it. First place to look with your symptoms. Link to comment Share on other sites More sharing options...
Eagle Posted September 20, 2012 Share Posted September 20, 2012 Agreed. Classic symptoms. Link to comment Share on other sites More sharing options...
kbusch18 Posted September 20, 2012 Author Share Posted September 20, 2012 Bypassed the resistor syptoms still the same Link to comment Share on other sites More sharing options...
HOrnbrod Posted September 21, 2012 Share Posted September 21, 2012 What year, model, engine? Put it in your signature so we don't have to guess. Tried swapping your fuel pump relay yet? Sounds like it's not larching when you release the key. Link to comment Share on other sites More sharing options...
Geonovast Posted September 21, 2012 Share Posted September 21, 2012 What kind of fuel pressure are you getting? Link to comment Share on other sites More sharing options...
deziped Posted September 21, 2012 Share Posted September 21, 2012 Maybe a vacummn leak at the MAP or TB or in between! Link to comment Share on other sites More sharing options...
kbusch18 Posted September 21, 2012 Author Share Posted September 21, 2012 no dice on the fuel pump relay , fuel pump kicks in real good not an issue where are the map and tb located Link to comment Share on other sites More sharing options...
HOrnbrod Posted September 21, 2012 Share Posted September 21, 2012 no dice on the fuel pump relay , fuel pump kicks in real good not an issue where are the map and tb located Yes, dice on the FP relay. The fuel pump relay kicks in (latches) after the engine starts and you release the key. It then sends the 12V operating voltage thru the ballast resistor to lower it then to the fuel pump. If your FP relay isn't latching or isn't receiving the IGN OFF signal the pump will quit as soon as you release the key from START to RUN. I think that's what your pump is doing, si? Link to comment Share on other sites More sharing options...
kbusch18 Posted September 21, 2012 Author Share Posted September 21, 2012 yes i will turn the key it will fire up or rumble then restart the cyle i can turn the key to off then back to on to keep doing it or just keep the key in the start position and it will do the cycle on its own i bought a relay and went through each relay and the symptoms remained the same Link to comment Share on other sites More sharing options...
kbusch18 Posted September 21, 2012 Author Share Posted September 21, 2012 by the way if i have three relays in a row which is actually the fuel pump relay if i am looking at it from the passanger side Link to comment Share on other sites More sharing options...
HOrnbrod Posted September 22, 2012 Share Posted September 22, 2012 A Renix guy will have to answer that. Also if you are not receiving the 12V signal to the relay a good or bad relay will never latch when the truck starts and the pump will not run. After you ID the FP relay get your meter out and check for 12V out of the relay. Or listen or touch it to see if it clicks. Then go to the ballast relay and check for 12V. All after you release the key. Link to comment Share on other sites More sharing options...
kbusch18 Posted September 22, 2012 Author Share Posted September 22, 2012 any thoughts there i replaced ign. switch, fuel pump relay, bypassed ballast resistor, i know fuel pump works, i agree it may be fuel, if it wasn't at least receiving fuel it wouldn't rumble every time by now Link to comment Share on other sites More sharing options...
cruiser54 Posted September 22, 2012 Share Posted September 22, 2012 2nd relay from the front is the fuel pump relay. Link to comment Share on other sites More sharing options...
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