need some help
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need some help
I found this forum and it seems like a good place to get help. I serched the forum for similar post but couldn't find the same problem I have, so I'm sorry if this is a repost.
I was driving my father inlaw's 1990 F150 I6 when I stopped shut it off to help my relatives move I went to start it up and it would crank but not fire. I turned the key to hear the fuel pump prime but it did not. I checked the fuses and checked the relief valve for preasure. Fuses were good but no preasure. I tried the front tank which I do not use because of a leak but that pump did not turn on either. I thought it was a bad pump so I bought a new sending unit/pump for the rear tank, but I stil don't here it turn on. The selector switch for front and back tanks showed the correct fuel level. I left the front take off being it isn't any good, I'm only planing on using the rear tank is this going to create a problem? I'm trying to avoid taking it in to a shop to save some money so I can't give you any diangostic codes. So thats why I'm here in hope of one of you kind people helping me out.
I was driving my father inlaw's 1990 F150 I6 when I stopped shut it off to help my relatives move I went to start it up and it would crank but not fire. I turned the key to hear the fuel pump prime but it did not. I checked the fuses and checked the relief valve for preasure. Fuses were good but no preasure. I tried the front tank which I do not use because of a leak but that pump did not turn on either. I thought it was a bad pump so I bought a new sending unit/pump for the rear tank, but I stil don't here it turn on. The selector switch for front and back tanks showed the correct fuel level. I left the front take off being it isn't any good, I'm only planing on using the rear tank is this going to create a problem? I'm trying to avoid taking it in to a shop to save some money so I can't give you any diangostic codes. So thats why I'm here in hope of one of you kind people helping me out.
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Originally Posted by LxMan1
Welcome to the forum 
Check the EEC relay and fuel pump relay. Both are under the hood.
There is also a high pressure pump on the frame that could be bad.
Check the EEC relay and fuel pump relay. Both are under the hood.
There is also a high pressure pump on the frame that could be bad.
If the high pressure pump is out wouldn't I still hear the in tank pump?
I did check to see how many volts are going to the fuel pump and it showed 7.4 volts does that sound right?
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Originally Posted by LxMan1
No, it should be 12V. Check the green fuel pump relay. It sounds like the contacts are bad and there is a lot of resistance in there.
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Originally Posted by LxMan1
That is the EEC relay. It controls ECM power. If the green one will plug in, try one of them there.
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From: Louisville,Ky.
The main EEC ground is the smaller wire going to the - terminal on the battery. Make sure it has a good connection.
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From: Easton,Ks
Next you should ground pin #6 of the VIP (test connector) with the key on and see if the fuel pump will run, by the way you do not have a pump on the frame.
Here is a diagram of your system.
http://i54.photobucket.com/albums/g9...el1990F150.jpg
http://i54.photobucket.com/albums/g9...taLinkConn.jpg
Here is a diagram of your system.
http://i54.photobucket.com/albums/g9...el1990F150.jpg
http://i54.photobucket.com/albums/g9...taLinkConn.jpg
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Originally Posted by subford
Also check the Inertia Fuel Shutoff switch, this may be your problem if you have not checked it. Just push the button on top and see if it clicks.
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From: Easton,Ks
Originally Posted by billsbeater
I've checked that and its ok. I'll ckeck pin 6 and ground it, what if it don't run, whats next?
Last edited by subford; Apr 25, 2007 at 04:37 PM.
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Originally Posted by subford
If the pumps do not come on with pin #6 grounded with key on you need to check for power at the Inertia Fuel Shutoff switch (both pins) to see if you have it there with the pin #6 still grounded and the key on.
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From: Easton,Ks
Check the voltage at the selector switch on the dash while doing the pin#6 thing.
7 volts at the Inertia Fuel Shutoff switch say to me that you are using the wrong test equipment. You are not loading the circuit with that high impedance meter.
Get a test light with a bulb in it so that you know what you have. A meter will make you chase your tail all day long, they are OK for some things on a truck but not for circuit tracing.
7 volts at the Inertia Fuel Shutoff switch say to me that you are using the wrong test equipment. You are not loading the circuit with that high impedance meter.
Get a test light with a bulb in it so that you know what you have. A meter will make you chase your tail all day long, they are OK for some things on a truck but not for circuit tracing.
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I posted my readings wrong its 7.5 volts at the inertia switch, when 6pin is grounded it reads 12.5 volts. I read that the power flows from the relay to the inertia switch then to the pump. If I'm getting the right volts at the inertia switch, what if I ran a new wire from there to the pump?