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HDGENE, Ford Senior Master/Diesel/Trans
Category: Ford
Satisfied Customers: 5130
Experience:  25 years Auto experience, Ford ,GM, Chrysler, Asian & European
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F-150: 1991 4.9 Ran well one day and won't start the next.

Customer Question

1991 4.9 Ran well one day and won't start the next. I have spark and I can smell gasoline.
Don't have a fuel pressure tester but I can hear the fuel pump working. It never shuts ioff but I don't know if it is supposed to because the truck has always popped right off.
Submitted: 1 year ago.
Category: Ford
Expert:  HDGENE replied 1 year ago.
Hello, the fuel pump wont shut off? even with the key in the off position? Do you have any fuel pressure if you depress the schraider valve on the fuel rail? It should pop off pretty good if you have fuel pressure of 30 psi
Customer: replied 1 year ago.
Yes, it shuts off when I turn off the ignition. I haven't done anything except check for spark. It was pretty late last night when I finally had time to look at it. I thought that if I got a solution from you guys today while I'm at work I could get it running tonight.
Expert:  HDGENE replied 1 year ago.
Ok take a tire pressure gauge and cycle the key to on and hit the fuel schraider with it, see if it registers anything. You will need 30 psi for the vehicle to run, you can also try spraying some carb cleaner into the intake and see if the vehicle runs for a few seconds, this would also indicate that you have spark but no fuel pressure or no injector pulse. Ideally you would want to run a test for codes using a scan tool, a Key On Engine Off test and see if any codes are stored,since you hear the fuel pump running when you cycle the key to on you, should have fuel pressure, but is it enough and do you have injector pulse. Thats what you need to see next
Customer: replied 1 year ago.
Okay-thanks. If no pressure, then the pump is bad? Do I need any special tools to check for injector pulse? I have to run so I'll check my email later. thanks again.
Expert:  HDGENE replied 1 year ago.
A noid light is best to check injector pulse, if you have spark you should have pulse. See if it will fire with some carb clean and c heck pressure first. Could also be related to a clogged fuel filter which can lower fuel pump output over time and overheat the pump
Customer: replied 1 year ago.
What is a noid light?
Expert:  HDGENE replied 1 year ago.
It plugs into the fuel injector and reads the pulse(rpm signal) as the engine cranks. It should blink rapidly when cranking. One side of the fuel injector connector has battery voltage with the key on the other is the ground (driver) to cycle the injector and rmake it fire