4.6 l engine starts but dies after 3 to 5 seconds - F150online Forums



4.6 l engine starts but dies after 3 to 5 seconds

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  #1  
Old 09-27-2005, 10:09 PM
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Question 4.6 l engine starts but dies after 3 to 5 seconds

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Problem started when I was 250mi from home. at first truck would run and then stall off and on. It was morning after I filled tank. I assummed it was bad gasoline. so I added some dry gas to tank. It seemed to help a little. I drove truck home 250miles. never stalled but had to work gas peddle to make it. If I step on it . it seemed to cough and if I eased on the pedal seems to run better.
Got home. in driveway. Now only starts . for few seconds. and then stalls.
truck has 154K on it. I installed new fuel filter. Did not fix problem. I turn on switch and can hear fuel pump turn on. One guy told me its fuel pump.
I think its something else.

Any thoughts ,suggestions would be appreciated.

Thanks

Mark-Fish
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  #2  
Old 09-28-2005, 12:23 AM
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You can check the fuel pump by having someone start it and pushing in the schrader valve to check for pressure (or just get a tester, adaptor kit, and let go of $100 in the process) I would also still wonder about that gas. If you get water in the tank, adding more gas isn't going to make the water disappear. Try some water remover, or drain the tank (thats a bizitch) ALso, do you have a CEL or does it just die? Check your vacuum lines for a rotton one, or a bad PCV.....There are a hundred things to check you know
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Old 09-28-2005, 01:50 AM
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I gave $35 for my fuel pressure tester. I would check that first. I had an 87 turbo T-Bird that did the exact thing you are describing. I was only getting 15 pounds of pressure from the pump. That is not enough to run the thing. The regulator could also be the culprit. A quick check for that is to take the vacuum line off it. If it has gas in it you need to replace it.
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Old 09-28-2005, 07:30 AM
 
Join Date: Oct 2004
Location: nj
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I have 2000 5.4 and on the back of the throttle body /intake there is a screwed in electronic device about the size of a fist.

The item opens and closes air intake like the old butterly on a carburator. It goes for about $80 . You can do it with 2 small bolts

Do a search on here, Somebody had a pic what do look for. It goes all the time from carbon build up and is fairly common. I replaced mine myself and was easy

I think search engine size idle stalling. If you don't find it here do a search on google... Can't remember if I found the answer here or not

Good luck
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  #5  
Old 09-28-2005, 07:38 AM
 
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Its called an IAC
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Old 09-28-2005, 09:10 AM
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my 1997 with 157k miles was doing the exact same thing. Went to Advance Auto and picked up a new IAC valve for like $50 i think.. took about 10 minutes to swap it out. runs like new now.
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  #7  
Old 09-28-2005, 03:18 PM
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I was having problems the other day with my truck stalling. I planned on cleaning the IAC, but before I got around to that, I noticed I was a quart low on oil. After dumping a quart in, my truck is running fine now.

I also cleaned my K&N air filter last night, and plan to get to the IAC and throttle body in the next week, just to avoid any future problems. I'm guessing my 19.5 hour trip evacuating Houston last week didn't help out.
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  #8  
Old 09-28-2005, 10:12 PM
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Well ,thanks for the tips. I believe I have eliminated the fuel pump, I have installed a new IAC . truck still runs 3 seconds then dies. Until I take off the intake on the front of the throttle body. then the turn starts and runs. I have voltage going mass air sensor. Could it be the Mass Air sensor is bad? the Air cleaner is one month old.

Thanks
Mark
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  #9  
Old 09-28-2005, 11:11 PM
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Quote:
Originally Posted by Mark-Fish
Well ,thanks for the tips. I believe I have eliminated the fuel pump, I have installed a new IAC . truck still runs 3 seconds then dies. Until I take off the intake on the front of the throttle body. then the turn starts and runs. I have voltage going mass air sensor. Could it be the Mass Air sensor is bad? the Air cleaner is one month old.

Thanks
Mark
There should be two vacuum lines on that intake piping. Are they both there and in good condition?
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  #10  
Old 09-30-2005, 04:37 AM
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Crankshaft position sensor, or camshaft position sensor is a safe bet...
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  #11  
Old 09-30-2005, 08:50 AM
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I got it running last nite. Was not anything major. I removed the mass air senor out of the equation. ran fine with all hoses. in place. then pluged in air sensor module in but didnt put it in the air chamber. truck still run. so I took some forced air and pushed it at senor. truck died. "faulty mass air filter" so I put some computer head cleaner on sensor. cleaned it and blew it out good. Put it all back together and bingo . Good to go. There must of been a dust particle or something on the air sensor. Thanks for your help.
Mark
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