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Old 05-10-2014, 04:07 PM   #1
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Unhappy my '87 F-150 won't start unless i spray gas in intake

My weekend truck with a 302 started acting up one weekend, engine wouldn't idle, engine hunting up and down, and then just got where it wouldn't start. turns over good, but won't start unless I spray gas in the intake. I've cleaned the idle air valve, checked for vacuum leaks, checked fuel pressure and have 45 psi with the engine off. With the engine turning over get about the same pressure. Have power to the injectors, and a slight pulse on the white injector wire with my test light while cranking the engine.

If I spray gas into the throttle body, it cranks, just won't stay running...

Any ideas or help?

Last edited by Bozemawm; 05-10-2014 at 08:59 PM.
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Old 05-10-2014, 04:13 PM   #2
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TPS?
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Old 05-10-2014, 04:19 PM   #3
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Thanks, but would the TPS keep it from starting?
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Old 05-11-2014, 10:22 PM   #4
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After you crank it a bit, pull a plug and see if it smells like gas to make sure the injectors are actually opening. Put some gas on a rag from the schrader valve and then (take it somewhere else) see if the gas on the rag burns. That would tell you something (without spending money anyway).
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Old 05-11-2014, 10:35 PM   #5
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Quote:
Originally Posted by Bozemawm View Post
Thanks, but would the TPS keep it from starting?
no it wouldnt.
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Old 05-11-2014, 11:30 PM   #6
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Originally Posted by 93F-150 View Post
no it wouldnt.
http://www.thirdgen.org/techboard/te...-cause-no.html

http://forums.corral.net/forums/gene...-starting.html

http://www.stangnet.com/mustang-foru...ectors.780137/

In fact a bad TPS WILL disable injectors and keep an engine from starting. FYI

"Yes a bad tps can prevent a car from starting. Will act like its in clear flood mode and won't trigger the injectors."

Last edited by fltdriver; 05-11-2014 at 11:33 PM. Reason: added a quote
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Old 05-12-2014, 10:09 PM   #7
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A Big Thanks to fltdriver for the TPS response. I checked and had a bad TPS, the sensor was open and would not read correct. Purchased a new sensor this afternoon, and am adjusting it now but ran out of daylight. Try again tomorrow afternoon. Thanks again!! Sure hope that solves all my issues. Glad to finally find something that was defective, I hate to just change parts.
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Old 05-15-2014, 10:22 PM   #8
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I installed a new TPS and set it, and the engine will still only start if I spray gas in the intake. It ran 30 seconds as long as I could keep spraying gas in the throttle body. I have 45 psi of fuel pressure, and not sure where to go next? Is it the injectors, or computer? I used my test light and have power to the injector red wire, and when spinning over the engine, the other wire blinks my test light when the test light is grounded.

HELP PLEASE..
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Old 05-15-2014, 11:02 PM   #9
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It may not help but have you tried unplugging the battery for a few minutes since you put the new TPS in? I know in caddys the computer needs reset but not sure on these trucks.

Also have you pulled your codes? They could pinpoint the issue

Last edited by fltdriver; 05-15-2014 at 11:04 PM. Reason: Pull codes
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Old 05-15-2014, 11:06 PM   #10
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BTW pull the codes before unhooking the battery or they will be erased
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Old 05-15-2014, 11:06 PM
 
 
 
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