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93 F-150 won't run.

Tiny
GREG2332
  • MEMBER
  • 1993 FORD F-150
  • V8
  • 2WD
  • MANUAL
  • 300,000 MILES
93 Ford F150 XLT 5.0, 5 speed manual trans, 300k+ miles, well maintained, 1 owner. Engine has good spark, turns over well, 40-42 psi fuel pressure at the rail, new air filters, wires, plugs, cap rotor, pcv and fuel filter. Fuel pump replaced last year. Will not catch and run, turns over like not getting fuel, but, can spray a short burst of ether and the engine instantly catches and goes into a high idle (2000-2200 rpm). Engine rpm is constant, does not vary. Can unplug the idle air solenoid and the engine dies. Have checked for an external vacuum leak, checked the booster for a leak, sprayed around the intake manifold with starting fluid and carb cleaner and get no indication of a leak. I suspect the idle air control solenoid as it is the original. Any suggestions?
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Thursday, July 21st, 2011 AT 12:47 PM

6 Replies

Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
You need to check the fuel pressure using a gauge and check the injector pulse using a noid light bulb. You're losing fuel. You just have to isolate the reason.
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Thursday, July 21st, 2011 AT 1:36 PM
Tiny
GREG2332
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  • 4 POSTS
Thank you for your quick response. I have checked the fuel pressure at the rail with a guage, checked after ignition turned on and fuel pump energizes, 40-42 psi. The fuel pressure does not drop significantly during cranking, 2-3 psi, and once the engine is running(after applying ether) the rail pressure is constant around 38-40 psi. I will check the injector pulse tonight. What do you think is causing the 2000-2200 rpm constant high idle once it starts?
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Thursday, July 21st, 2011 AT 1:47 PM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
So, you are saying it stays running after started with ether? If so, you need to look for a severe vacuum leak.
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Thursday, July 21st, 2011 AT 1:52 PM
Tiny
GREG2332
  • MEMBER
  • 4 POSTS
I have checked all external sources for a possible vacuum leak, including the egr, intake manifold, throttle body mounting gasket and shaft. Disconnected and plugged all connections on the vacuum tree on the manifold. This is why I suspect the idle air control solenoid is not fuctioning correctly. Unless there is an internal engine gasket blown, but I have no evidence of this from the exhaust, no white or blue smoke, no antifreeze or oil smell.
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Thursday, July 21st, 2011 AT 1:59 PM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
You might be right.
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Thursday, July 21st, 2011 AT 2:09 PM
Tiny
GREG2332
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Thanks, I was hoping I didn't miss something obvious while I was checking it over.
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Thursday, July 21st, 2011 AT 2:14 PM

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