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Ron
Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 23001
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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I have a 92 f150. motor cranks over and has spark. injectors

Customer Question

i have a 92 f150. motor cranks over and has spark. injectors are spraying. but wont run. the only way it will stay running is if i spray starting fluid in the intake. i cleaned all injectors and replaced fuel pump. and replaced ecu. any idea why its not staying running
Submitted: 3 months ago.
Category: Ford
Expert:  Ron replied 3 months ago.

Hello, my name is ***** ***** I am a professional here at Justanswer. Thank you for your question and I will assist you with your concern.

If you are sure you have good spark to the spark plugs as well as proper fuel pressure and injector pulse have you removed the spark plugs and ran a complete engine compression test?

Customer: replied 3 months ago.
i havenot. but when i spray in starting fluid it will idle and i can rev it up and down. so i asum its on time and has plenty of compression. motor will run perfect just not on its own
Expert:  Ron replied 3 months ago.

Okay if you install your fuel pressure gauge what is the fuel pressure reading while your adding fuel?

Customer: replied 3 months ago.
38
Expert:  Ron replied 3 months ago.

Okay so you have 38 PSI of fuel pressure good spark at the spark plugs and injector pulse then the engine should start and run on its own. Are you sure your injectors are firing?

Customer: replied 3 months ago.
i pulled the rail and watched then spray. i cleaned them aswell by accuating the injector and praying through them
Expert:  Ron replied 3 months ago.

Something dose not make sense here, you sya you have good spark and injector pulse and proper fuel pressure but yet it only runs with added fuel. Which indicates a fuel concern. Are you sure the fuel in the tank is okay?

Customer: replied 3 months ago.
put new gas in it.
Expert:  Ron replied 3 months ago.

Okay as I am sure you know it take good spark to the spark plugs, injector pulse at the injector , proper fuel pressure and good compression for the engine to start and run. If your 100% sure you have all of theses things the engine really should start and run.

Customer: replied 3 months ago.
i hooked the fuel pressur gage inline and it gose up to 50 psi while cranking.
Expert:  Ron replied 3 months ago.

If you getting 50 PSI that to much pressure, are you fouling the spark plugs?

Customer: replied 3 months ago.
i just replaced all plugs. they did look rich
Expert:  Ron replied 3 months ago.

Well in that case its not likely over fueling, if the only way you can get it to run is with added fuse then the engine is starving for gas.

Customer: replied 3 months ago.
i know that. i just looked up the specs and it said koeo 50-60psi and engin at idle is 35-40 psi. would any electronics case it not to run besides distributor
Expert:  Ron replied 3 months ago.

Yes you are right on the 4.9 engine. The if your reading are correct then this is not the issue. You say it will only run if you add fuel . That tells me the engine is not getting gas. Im out of ideas at this point.

Customer: replied 3 months ago.
the nobe light in the injector looks week. how would i make it stronger
Expert:  Ron replied 3 months ago.

Are you getting 12 volts at the power feed wire (red)?

Customer: replied 3 months ago.
12.34
Customer: replied 3 months ago.
i put in a bran new distributor aswell.
Expert:  Ron replied 3 months ago.

The injectors are controlled by the ground switching signal from the PCM and if the injector are spraying as you have stated then you have injector pulse.

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