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1. Fuel Pump w/strainer
2. Fuel Filter
3. Fuel Pressure Regulator
4. IAC (Idle Air Control) unit
5. TPS (Throttle Position Sensor)
6. EEC Unit
Sympton...
1. Will not run without having to continuously pump the pedal?? I can keep it running all day like this.
2. Will crank and has spark.
3. Checked the injector pulse with a noid light and it seemed pretty weak compared to others I have tested. (Barely lights up at all)
I really need a Ford Guru for this one! Are there anymore of them out there?? This is an RV that I'm helping my ederly neighbor get running again. They are great people and really can' t afford to have it towed 50 miles to the dealer for something maybe we can fix here. So if you're reading this and you can help or you know someone that can help, please send me a message or post it.
I seem to remember something like this in another thread, and it ended up being a fuse. If memory serves, it was something about a circuit that was live when the key was turned to Start, but not when turned to just Run.
Thanks for the reply Brad. I'm willing to check circuits if I have to. Any idea where to start?? I did a visual on some of the main wiring harnesses to check for corrosion or hot spots with no luck. I sure would appreciate any more info.
I did a quick search and found the thread I was remembering, but it was dealing with a carbed engine. The fuse in question is the "Aux Fuel Tank" fuse. If it blows, the fuel pump will only run when the key in is the "Start" position.
maybe the map sensor went out or a vaccum to it is loose,know of one guy had a very rough running engine,replaced most of the sensors,fuel pump,etc,turned out to be the ecm,,,wonder if it could also be the hall effect pickupcoil or the ign module but those only control spark,,check the fuel pressure and get back to us,also check for a severely blocked exhaust,but doubt it could be that since you say you have to keep pumping it to keep it running,,,,
Last edited by mustangman; Apr 20, 2006 at 02:27 PM.
As far as the fuel pressure, when I first turn on the ignition and the fuel pump runs for a couple of seconds the guage can read between 30-40 psi. It doesn't change when I crank it?? What components control injector timing??
try replacing the Manifold Air.Pressure.M.A.P sensor,,measures vaccum and adjusts fuel to injectors,by sending different voltage readings to the main computer,does the ecm have a good ground to it? i also heard of one guy with his efi 460,some of the injectors were gummed up from sitting so long without running,thus not delivering fuel,you can hear each one click with a stethescope or by feeling them,my 460 is a 92 efi so iam interested in what it could be should it happen on mine,,good luck and post back the news
I have the same rig just a year newer. You checked the fuel pressure which is good but you also need to check the volume. Pressure and volume do not always go hand in hand. There are also technical service bulletins on these pumps that might apply to yours. Alldatadiy.com is a good resource. Oh, almost forgot, check any codes that might be stored.
Last edited by T18skyguy; Apr 22, 2006 at 09:56 AM.
try replacing the Manifold Air.Pressure.M.A.P sensor,,measures vaccum and adjusts fuel to injectors,by sending different voltage readings to the main computer,does the ecm have a good ground to it? i also heard of one guy with his efi 460,some of the injectors were gummed up from sitting so long without running,thus not delivering fuel,you can hear each one click with a stethescope or by feeling them,my 460 is a 92 efi so iam interested in what it could be should it happen on mine,,good luck and post back the news
Is there a way to diagnose or test the MAP sensor b4 I buy the replacement?
And as far as the injectors go, I did go through each one and energized with 12v positive to the red wire and everyone was clicking real nice. In fact when I did this was when it would actually get fuel to the cylinder to fire?! Thanks again everyone for your greatly appreciated help!
Scott Campbell
Goldsboro, NC
I have the same rig just a year newer. You checked the fuel pressure which is good but you also need to check the volume. Pressure and volume do not always go hand in hand. There are also technical service bulletins on these pumps that might apply to yours. Alldatadiy.com is a good resource. Oh, almost forgot, check any codes that might be stored.
I hear ya on the volume. What type of GPM would I be looking at as acceptable? As far as codes????? New computer and I didn't scan the old one. So no codes yet, at least I don't think so???? I will check that too though since I have had it running by pumping the heck out of the pedal. Maybe it stored a code?. Thanks for the info!!
Scott Campbell
Goldsboro, NC
It was the MAP sensor. Thanks to everyone for your input especially "mustangman" who had the winning suggestion. I hope this thread helps others too! It was a very trying diagnosis!
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