4.9 makin me @#$%@## nuts!!
11-08-2008, 03:47 PM
#1
4.9 makin me @#$%@## nuts!!
1990 f150 new fuel pump,regulator,injectors,map sensor tps sensor. 92,000 miles 5 speed 2wd.she wont start .all new ignition plugs wires cap distributor. had 3 diff pumps in(single tank rear mount) has pressure- wont start.pump just runs continuously wont pressurize. 2 diff regulators same effect. is there something between pump and reg that could be causing this?not a leak to found anywhere. New filter as well.It starts sometimes if i plug in the little error computer,but only rarely.3 mechanics came up with nothing if i have to take it to ford imght as well burn it the ground. running out of parts to replace.only code i get is bad neutral start switch
11-08-2008, 04:57 PM
#2
Senior Member
How much is the fuel pressure? 15-20 PSI is enough for a start in my 4.9. Have you checked for a spark? Connect a plug to any wire and put it on any metal engine part. Have someone press the clutch and turn the starter on. Watch for a spark not touching the plug. Check the fuel pump relay. If the pump runs continiously that might point to a bad computer, but you still must have pressure in the system.
11-09-2008, 11:13 AM
#4
thanks
more than enough fuel flowing-but the pump runs continuosly. It should run then stop when you turn the key. If I plug in the little Actron code reader and put it to test -it some times stops the pump and the engine will start.plenty of spark- timing was set deadon last time she ran.new eec relay new fuel pump relay.is there another solenoid that is part of the fuel system?
11-09-2008, 10:26 PM
#6
it cranks fine. There is normally an audible click(solenoid?)after you turn the key and hear the pump run-click then pump stops then engine starts. All i get is a continuously running pump.you can crank it until the battery dies but no fire.If you hear the click-it fires right up!now i cant even get the code reader to self test! Where is the cpu in this?I paid for one already but wasnt there for the installation.Where do i go from here.This truck is cherry. garage kept since 91. built many 5.0's this thing is killin me and there arent any mechanics around that can fix anything besides an obdII system-which is pretty brainless. could this be a ground problem? is there a check valve between the pump and the fuel rail?It seems like the fuel is just running from the tank to the rail and back to the tank.What about the charcoal cannister?is that on the lpass side by the alternator?how do you test that?after i changed egr and o2 sensor got 18mpg for about 100miles. now im stuck.this has to be something stupid there isn't much left to replace.ANY HELP is greatly appreciated.
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11-09-2008, 11:46 PM
#8
The computer is behind the drivers side kick panel in the cab. You don't need to test the charcoal canister, just see if it has fuel in it, which it shouldn't. There are 3 things (actually 4) that will keep the fuel system from pressurizing. #1- the regulator which you have changed. #2- the injectors which may be sticking open. You should try to start it and if it doesn't pull the plugs and see how wet they are. #3 and #4- the FDMs in each tank. They are what prevents fuel from being pumped back to the incorrect tank. If the front tank is selected then the front tank should receive the excess fuel returned, and vice-versa. If fuel is being pumped back to the incorrect tank then the tank that shouldn't be receiving the fuel has a bad FDM. The FDM isn't sold separately, it's included with the fuel pump. FDM= fuel delivery module, it's just a valve.
11-19-2008, 10:41 PM
#9
ok -broke down and took it to Ford.360.00 for diagnostics and gave me back the keys with some lame bs about should have bought genuine ford parts! Didnt fix anything-God I wish I was able to screw people without a second thought!! Took it home(towed),walked away for a few days. Fresh beer in hand I stared at it in the driveway and remembered my 78 king cobra in high school and remembered problems with connectors. Scotchbrite and dielectric grease and every connection i could find in the harness, Mallory coil,wires, platinum plugs,few more beers-runs great
11-23-2008, 12:57 AM
#10
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Had a similar problem, although my pump just kept running after being shut down. Fuel pump relay was sticking. Replaced the relay, no more problem. Until I replaced it I would just disconnect it to shut off the pump and then reconnect it. you may have temp reset it when you disconnected and reconnected. Just something to keep an eye on if it starts again. Btw, the relay is located driver side top of engine compartment. Small rectangular block with 3-4 relays in it.