No fuel pressure or Fuel Injector Pulse

Tiny
PCHEFSONYA
  • MEMBER
  • 1988 FORD BRONCO
  • V8
  • 4WD
  • AUTOMATIC
I just installed new engine but have no start. There is no fuel pressure or fuel injector pulse. Checked fuel pump relay and all fuses and they are all good. Im at a loss what to check next.
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Saturday, July 30th, 2011 AT 4:12 PM

16 Replies

Tiny
JDL
  • EXPERT
Do you have spark at the plugs, engine cranking? If you don't have anything, Check for rpm/pip signal, comes from the tfi module. I can't say the module is faulty. With the key on or cranking do you have primary voltage at the coil?

Any applicable trouble codes?
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Saturday, July 30th, 2011 AT 6:18 PM
Tiny
PCHEFSONYA
  • MEMBER
Yes I have spark and when I spray carb. Cleaner in the throttle plate the truck will run. As soon as I stop spraying the truck shuts off. I power probed the fuel pump and the pump came on, but still will not run, no power going to the fuel injectors.
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Sunday, July 31st, 2011 AT 4:43 PM
Tiny
JDL
  • EXPERT
You may have two fuel pumps, low pressure pump in the tank, high pressure pump along driver side frame rail, under the hood.

With engine cranking, check voltage to and from the inertia switch. Engine cranking use a noid lite for injector plug, does it pulse? Voltage to the injector/s is a red wire, goes hot with the key on.

Any applicable trouble codes?
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Sunday, July 31st, 2011 AT 5:47 PM
Tiny
PCHEFSONYA
  • MEMBER
Yep I already tried and no injector pulse. No trouble codes come up.
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Sunday, July 31st, 2011 AT 6:24 PM
Tiny
JDL
  • EXPERT
Any voltage on that red wire at injectors, key on? Saying no pulse can mean either no voltage or no ground, which is it?

With two fuel pumps, did you check both?
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Sunday, July 31st, 2011 AT 6:28 PM
Tiny
PCHEFSONYA
  • MEMBER
I have voltage on both wires, going to the injectors. Both pumps are good. I checked power on both sides of the inertia switch and no power either side.I disconnected the connector and checked it with a test light. Before installing the engine I had communication with computer, after installation no communication at all.
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Sunday, July 31st, 2011 AT 7:00 PM
Tiny
JDL
  • EXPERT
Is the engine and computer compatible? Same year--make--model-- engine size? If not, it may not work?
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Sunday, July 31st, 2011 AT 7:28 PM
Tiny
PCHEFSONYA
  • MEMBER
Its the original computer from the engine I switched over, it came with the truck.
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Sunday, July 31st, 2011 AT 7:31 PM
Tiny
JDL
  • EXPERT
Fuel pump relay diagram below. Yellow wire is voltage from ignition switch. When the relay is energized, that line with the arrowhead moves to the yellow wire terminal, voltage then flows to inertia switch. The coil side of relay has to have voltage and ground in order to energize. The red wire is voltage, same voltage that goes to injector/s. The tan wire with white tracer is ground for the coil side of relay, controlled by the computer.
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Sunday, July 31st, 2011 AT 7:44 PM
Tiny
JDL
  • EXPERT
You may have to check all voltage and grounds at the computer.
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Sunday, July 31st, 2011 AT 7:46 PM
Tiny
PCHEFSONYA
  • MEMBER
I have power going to the relay on the yellow wire, but have no power going to the inertia switch. Is it possible to reground the computer?
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Sunday, July 31st, 2011 AT 8:22 PM
Tiny
JDL
  • EXPERT
What about voltage on the red wire?
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Sunday, July 31st, 2011 AT 8:35 PM
Tiny
PCHEFSONYA
  • MEMBER
When I turn the key on I have voltage going to the red wire. When I uplug injector plugs I have voltage on both sides.
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Sunday, July 31st, 2011 AT 8:39 PM
Tiny
JDL
  • EXPERT
Make sure battery has a full charge and fuses are all ok. Take the computer connector loose, check that no pins are bent or pushed back in the connector. Yellow wire pin #1 is voltage from ignition switch. In the diagram are ground pins and v-power. I don't know what else to tell you.
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Sunday, July 31st, 2011 AT 9:03 PM
Tiny
PCHEFSONYA
  • MEMBER
Thanks, I will check out the connectors to the computer as you suggested.I'm with you, I don't know what else to check. Thanks for your help.
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Sunday, July 31st, 2011 AT 10:06 PM
Tiny
JDL
  • EXPERT
I'd hate to see you replace the computer and it turn out to be something else.
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Monday, August 1st, 2011 AT 3:03 PM

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