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Eletrical problem to fuel injectors

Tiny
JEBBER
  • MEMBER
  • 1991 FORD RANGER
  • 160,000 MILES
Eletrical problem to fuel injectors. With ohmeter, With ignition in the on position, reading both positives from leads to injectors.I've changed ignition control module, looked at wireing harnesses. Engine runs only with starting fluid shot into the air intake. What more should I be looking at.
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Wednesday, January 23rd, 2013 AT 4:28 PM

17 Replies

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
What is litre size of engine? With key on, no crank, you will have voltage on both legs, no ground. With engine cranking, should be pulse on ground circuit. Was injector plug connected or unconnected when you tested? Another issue with your test could be more than one injector sharing the same ground. You would have to unplug other injector/s that share that ground. Hope I didn't confuse.

Can you check for applicable trouble codes?
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Wednesday, January 23rd, 2013 AT 5:19 PM
Tiny
JDL
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Maybe I misread your post, you did an ohms test or voltage test on injector circuits?
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Wednesday, January 23rd, 2013 AT 5:21 PM
Tiny
JDL
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Just to add, use a gage and check fuel pressure.
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Wednesday, January 23rd, 2013 AT 5:22 PM
Tiny
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JDL: 4.0 engine. Voltage test. Injector plug disconnected.I tested with negative lead of my V, A, Ohms meter on metal of engine and positiv lead to either leads of injector plug with same results. Reads 12 volts with key on. Engine crank only small drop in voltage on meter.I have good fuel pressure. Could there be a bad ground or short.
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Wednesday, January 23rd, 2013 AT 8:11 PM
Tiny
JDL
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Use a noid lite to check for injector pulse. You might be able to use an led test lite to check for injector pulse, engine cranking. Can you check for trouble codes? How long since a tune-up?
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Wednesday, January 23rd, 2013 AT 9:49 PM
Tiny
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JDL: How can I check for codes when engine doesn't run? I have electronic fuel injection, no distributor. I forgot to say THANK YOU for your input. To check for pulse, does plug need to be connected to injector? I will try tomorrow. Thanks again.
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Wednesday, January 23rd, 2013 AT 10:44 PM
Tiny
JDL
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You unplug injector to check for pulse. You can check some codes, key on engine off. Note the picture. You use jumper wire between two connectors. The connectors should be right front inner fender panel. When you hook up the jumper, key on, no crank, the mil on the dash may start flashing, you count the flashes to get the codes. If that doesn't work, hook up analog voltmeter, like in the picture and count needle sweeps. It may take a few tries for you to get used to it. It can be two or three digit codes.
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Wednesday, January 23rd, 2013 AT 11:20 PM
Tiny
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JDL: I hooked everything up just like the picture. No flashing on dash nor sweeps on my meter. My connections with meter were good for I was reaing 12 volts. Turn key on, only small drop in volts.I even tried different configurations with the hook-ups. Is it no codes no problem? Thanks.
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Thursday, January 24th, 2013 AT 6:09 PM
Tiny
JDL
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I think there should have been a code, 11 or 111. You may need to use a spade terminals on that jumper to get good connection.
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Thursday, January 24th, 2013 AT 9:47 PM
Tiny
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JDL: With KOEF I read codes 21, 16, and24 on the EEC-IV test plug. Would any of these codes effect pulse to injectors?

THANKS.
Jebber.
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Thursday, January 31st, 2013 AT 9:05 PM
Tiny
JDL
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Engine cranking, did you visually check for spark at the spark plugs. The reason I asked, without rpm signal, no injector pulse. No spark.

I don't believe those codes would stop injector pulse.

By the way, good job on checking the codes.
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Thursday, January 31st, 2013 AT 10:35 PM
Tiny
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JDL: I visually checked spark at plugs. Also, engine runs off of starting fluid.I tested again with my analog meter set on DC Volts, neg. Lead on engine ground, pos. Lead on either lead of injector harness. With KOEO reading 12 volts.I connect neg. And pos. Leads of meter to both leads of injector harness and KOEO no volts, no sweep. Engine cranking, no volts, no sweep of meter. I'm clueless in 10 degree weather.I also had the battery disconnected overnight at one point. Would that erase codes from computer?

I thank you very much for your input!
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Friday, February 1st, 2013 AT 4:50 PM
Tiny
JDL
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Not sure where to go from here? Two of my databases showed different meanings for one of the codes, which could possibly cause an issue. I'll try to double check?
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Friday, February 1st, 2013 AT 5:24 PM
Tiny
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JDL:

Thanks.
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Friday, February 1st, 2013 AT 5:57 PM
Tiny
JDL
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The code 16 could be the issue? I would want to check pip signal from ignition module to computer. You would need sometime that would react to pulse. Not an analog meter. I can't use the procedure in my database, it says to use a break-out box.
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Friday, February 1st, 2013 AT 8:56 PM
Tiny
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JDL: Thanks for replying.I don't know what all that means, but I will keep trying. This 91 Ranger i've had since Dec. Of 90.
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Friday, February 1st, 2013 AT 9:22 PM
Tiny
JDL
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If not a wiring circuit problem, I'd have to suspect the ignition module, for distributorless ignition. I hate to see you throw parts at it. I can't be sure?
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Friday, February 8th, 2013 AT 5:46 PM

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