she's got fuel she's got spark but she still wont fire
09-04-2007, 05:35 PM
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she's got fuel she's got spark but she still wont fire
I just was given a 1986 f 150 for free it's got a 5.0 in it and it's fuel injected. I was told that it needed fuel pumps but when i started looking into it and relized that the fuel pumps were not getting power so i trouble shooted some more and figured the fuel pump relay was gone well after trying 5 difreant bran new relays i'm guessing its not the relay. But if i jump the leads from the harness that the relay plugs into the fuel pumps come on with the key on or off it dont matter. So then i thought well lets try starting it now that i have fuel going to the motor but had no sucsess the truck will not start unless i put fuel directly into the intake. If i just pus some fuel in the intake she fires right up until it runs out of gas of course my quetion is if the fuel pumps are on and the fuel rail has presher and it has plenty of spark why wont she fire. I still havint got a relay to work in it yet i've just benn jumping the harness and turning the pumps on and trying to start it but it wont start.
Could it be that the relay has to be there and working to tell the computer to bring power to the injectors or is there something else going on with the injectors. I got fuel and spark but still wont fire up i'm out of awnsers any help would be greatly apreciated. Is there a wire conected to the ignition that turns that relay on or something that inm missin
Could it be that the relay has to be there and working to tell the computer to bring power to the injectors or is there something else going on with the injectors. I got fuel and spark but still wont fire up i'm out of awnsers any help would be greatly apreciated. Is there a wire conected to the ignition that turns that relay on or something that inm missin
09-04-2007, 07:51 PM
#2
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Are you sure the pumps are delivering fuel - thinking plugged filter, the fuel rail is air-bound, or the like.
I don't know why the injectors would not operate based on the status of the relay. If you're jumpering the relay, the rest of the system ought to not be able to tell the difference.
I don't know why the injectors would not operate based on the status of the relay. If you're jumpering the relay, the rest of the system ought to not be able to tell the difference.
09-05-2007, 01:03 AM
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I'm posative the pumps are pumping fuel to the motor there is a shrader valve on the fuel rail and when the pumps are on i can stick a screw driver in the valve and fuel comes squerting out with a lot of presher so there is defenetly fuel there. and i pretty sure that it's not air bound so i'm not really sure whats goin on.
09-05-2007, 01:55 AM
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You might check to see if the fuel pump cutout switch is working....it makes sense that if you trigger the cutout you would also want to kill the injectors as well in the case of an accident. Good luck....
09-06-2007, 05:26 PM
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are you talkin about the inertha switch or is there another one besides that. I took a meter to the injector plugs today and tuned her over i'm not getting any power at all to my injectors. could it be the eec [electronic engine control] Only reason i say that is because my fuel pump relay wont work i have no power at the injecters and thee eec controlls all that right.
09-07-2007, 02:14 AM
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I guess you could call it the inertia switch.....the one that is designed to shut your fuel system down in case of an accident. I would spend a few minutes to check this one with a meter just in case it is your problem. If it is not , I would buy a manual with a wiring schematic and start from square one on the fuel circuit. I might even have an old chilton from my 84 f150 days...I will look for it. Good luck......BD.
09-07-2007, 07:15 AM
#7
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If its not the inertia switch I am betting on a bad ground, bad ecu or bed EEC relay. The reason I say this is the pump is controlled by the computer. It turns the pump on for a few seconds when the key is turned to the on position to prime the rails then it turns it back on in start and run. The EEC relay is usually right next to the fuel pump relay.
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09-08-2007, 11:44 AM
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well guys i have found a bad ground and when i fixed it everything started working the truck will still not start unless i put fuel in the intake but once it is started it runs awsome. The truck did sit for over tgwo years so i'm thinking dirty injectors and maybe a tune up but it wont start on it's own it needs a little help by puting fuel in the intake but when i turn the key everything works now the fuel relay clicks the pumps kick on for a few sec and the injectors have power now. Almost there just need to figure out how to get it to start on it's own thanks for all your help everyone.
09-08-2007, 11:57 AM
#9
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well guys i have found a bad ground and when i fixed it everything started working the truck will still not start unless i put fuel in the intake but once it is started it runs awsome. The truck did sit for over tgwo years so i'm thinking dirty injectors and maybe a tune up but it wont start on it's own it needs a little help by puting fuel in the intake but when i turn the key everything works now the fuel relay clicks the pumps kick on for a few sec and the injectors have power now. Almost there just need to figure out how to get it to start on it's own thanks for all your help everyone.
