hard starting 4.0
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Trouble shooting is going slow do to work and college classes, homework ect. I wont have time to check the pressure untile saturday. I will buy a pressure tester to do the job. How do I check the pressure exactly? Aftrer I put the gauge on the rail I check it with the key on then with the engine running, right? then after I shout the engine off I should see how long it takes to loose pressre.
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Joined: Nov 2006
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From: Lynchburg, VA
Originally Posted by mike0179
Trouble shooting is going slow do to work and college classes, homework ect. I wont have time to check the pressure untile saturday. I will buy a pressure tester to do the job. How do I check the pressure exactly? Aftrer I put the gauge on the rail I check it with the key on then with the engine running, right? then after I shout the engine off I should see how long it takes to loose pressre.
http://fords.kilonet.org/ken00/FuelPressureTesting.doc
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Joined: Jan 2004
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From: SW Va
Well Mike, you could probably make loan of a fuel pressure test gauge, at your favorite autoparts store. Most have a loan-a-tool program, in which you make a refundable deposit for loan of a needed tool.
Disable the fuel pump, crank the engine until it stops trying to start.
Put your safety glasses on & connect the gauge to the fuel rail test valve port.
Re-enable the fuel pump.
Go to KOEO & read the fuel pressure, note the time & check for pressure drop over the specified time in your repair manual, for your particular engine.
Disable the fuel pump, crank the engine until it stops trying to start.
Put your safety glasses on & connect the gauge to the fuel rail test valve port.
Re-enable the fuel pump.
Go to KOEO & read the fuel pressure, note the time & check for pressure drop over the specified time in your repair manual, for your particular engine.
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well, i havent had time to check the pressure yet, but it tried cycling the key several times and it dosent help. I replaced the ect and the iat sensors and that didnt help. I read that the maf could be the culprit. I cleanded it and that didnt help either. I unplugged the maf while the engine was running and the engine hesitated for a instant and ran the same as when it was plugged in, even at all every rpm and under load, when I plugged it back in it did the exact same thing like when I unplugged it. I read that it should change things when unplugged, I read that it could be in limp mode because of the bad maf, there are no codes. thanks
Logistics Pro
Joined: Jan 2002
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From: suburban atlanta
You *should* get a code when you run with the MAF disconnected. If not, you may have a defective ECM. You should be able to get a code by disconnecting most sensors as they lose the 5v 'reference' signal back to the ECM and it doesn't like that.
tom
tom
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How long should it take before I get a code after I unplug it? Should there be a change in the engine when its unplugged? Someone told me the computer could be in limp mode were the computer runs off of factory set values.
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Joined: Jan 2002
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From: suburban atlanta
Almost immediately. You should check that you get all the 'OKeyDoke' codes when you run the test. If you get nada, it is brok.
The computer will have a code there if it is running in limp-home mode. But, if it can't tell you it is OK, it may not be able to tell you it is broken.
t
The computer will have a code there if it is running in limp-home mode. But, if it can't tell you it is OK, it may not be able to tell you it is broken.
t
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Well. I finally Took the truck in to a mechanic to see what the problem was and what he discvered was that the person who tunned it up before I purchased it in occtober put plugs that were to cold for the engine. He says that is a common mistakes with ford vehicles done by some mechanics, hes seen it a few times. I hope this will help with those off you who cant find the cause.
Thanks to all of you.
mike
Thanks to all of you.
mike
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