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Engine is not starting

Tiny
LOTSABOOST
  • MEMBER
  • 1994 ISUZU RODEO
  • 132,000 MILES
I have a 1994 Isuzu Rodeo with the 3.2L V6. It has been sitting for quite some time and now I can't get it running. I have replaced the Fuel Pump and Filter, new plugs, fresh gas. I have good spark and ample fuel pressure. The car fires with starter fluid. The injectors do not appear to be pulsing. The plugs come out dry after attempts to start. I have checked grounds and any connections I can think of.

The pump and filter were replaced due to lower pressure at the fuel rail. No codes from the port. Received all clear dtc 12. The car does not have a working alternator on it but all start attempts have been on a fully charged battery with a jump from a running vehicle connected.

The injectors are getting 12 volts with the key on.

Where is the ground for the injectors I should check? Is it directly at the ecm which is in the driver's side kick panel I would assume or is there something in the engine bay I should be looking at? Also could a lack of power due to not having an alternator be the issue? Could a bad for cause the injectors not to pulse in any way?

Im am getting power to the injectors, I tested the connector with a voltmeter with the key on. 12 volts. Where should I look for a corrosion problem?

All the wires and grounds look okay. I traced as far as I could besides going into the firewall. Just to clarify, With multiport injectors doesn't the ecm strobe the Ground for the injectors? Constantly feeding them power. That had always been my understanding.
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Thursday, October 27th, 2011 AT 4:42 AM

39 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
It sounds like you have one of two problems, first is the ECM relay is shorted out and not supplying power to the ECM or you have an ECM that is out and needs replacement. Check to make sure the ECM is getting power and ground.

Here are some guides and diagram (below) that will help you get the problem fixed.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

and

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

If you are not getting power to the injectors using a test light, a bad ground isn't the issue because you are creating your own with the test light.

Here is a guide that can help for generic problems.

https://www.2carpros.com/articles/car-cranks-but-wont-start

You need to check the injector resistance for me. You should have 11.8 to 12.6 ohms of resistance. Additionally, power to the injectors should not be constant. It should strobe on and off as the injectors. That is why I feel you either have a short applying power all the time or the ECM is bad. Take a look at the wiring schematic I attached. The power to the injectors comes from the ECM. I can't find the exact voltage they should be getting, but 12 volts sounds very high.

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

Please let us know what happens so it will help others.

Cheers
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Friday, October 28th, 2011 AT 4:33 AM
Tiny
LOTSABOOST
  • MEMBER
  • 4 POSTS
I checked the resistance on the fuel injectors and it is good. Its not easy to do on this vehicle because they are under the intake manifold.

I will be on the search for a decently priced ecm. Also, It was my understanding that in a multi port injector vehicle, the ecm strobes the Ground for cycles not the power. They are fed constant power. Is this correct?

I replaced the ECM relay and I can hear it working so I don't think that is it.
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Friday, October 28th, 2011 AT 5:40 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
You should only get power when the engine is cranked and it shouldn't be constant. Something tells me rather than checking the injectors, you should be checking the rest of the wiring to the ECM since the problem seems before them. I still feel there is a short to a power source or the ECM is bad.
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Friday, October 28th, 2011 AT 7:25 AM
Tiny
LOTSABOOST
  • MEMBER
  • 4 POSTS
I have a replacement ECM on order, should be here tomorrow. I will keep you updated. Thank you for your time. BTW, I replaced the alternator so lack of power from the battery/alternator is out of the question. Just trying to eliminate possibilities.
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Wednesday, November 2nd, 2011 AT 11:42 PM
Tiny
LOTSABOOST
  • MEMBER
  • 4 POSTS
I got the replacement ECM and now I have injector pulse. I have a feeling Im lacking fuel pressure somehow. The engine is running now by I have low power. I think the timing belt might have jumped, on to the next problem! Thanks for the help you guys are great.
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Friday, November 4th, 2011 AT 12:56 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Glad you could get it fixed, that kind of problem can be tough. Please use 2CarPros anytime we are here to help

Cheers
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Friday, November 4th, 2011 AT 1:24 AM
Tiny
RENEGADE65
  • MEMBER
  • 29 POSTS
The camshaft position sensor provides information on camshaft position the pcm uses this information along with the crankshaft position sensor information to control fuel injection synchronization.
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Saturday, January 5th, 2013 AT 5:04 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,665 POSTS
Great addition to this thread! Please feel free to help out on the site whenever it can add information that will help.

Best, Ken
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Monday, March 13th, 2017 AT 2:45 PM
Tiny
TILEGUY
  • MEMBER
  • 5 POSTS
  • 1994 ISUZU RODEO
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 120,800 MILES
Engine Mechanical problem
1994 Isuzu Rodeo Question 6 cyl Four Wheel Drive Automatic 120800 miles

I have a problem on cold starts with my 1994 rodeo. If the engine fails to start the first time (which is almost all the time) the engine floods and won't start. Vehicle seems to run fine after starting, but gets poor mileage. I replaced the o2 sensor and plugs, which does make it run better, but the starting is a problem.
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Monday, March 13th, 2017 AT 2:47 PM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
When it wont start have you verified spark? When will it finally start? Check the fuel pressure regulator, mounted on the fuel rail with a vacuum line to the intake manifold. If any fuel is present in the vacuum line, repalce the regulator. Any check engine light? If so have it scanned for codes
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Monday, March 13th, 2017 AT 2:47 PM (Merged)
Tiny
TILEGUY
  • MEMBER
  • 5 POSTS
I have checked for spark and there is spark. It will start only after taking plugs out and drying the fuel off of them. I haven't checked the fuel pressure regulator yet, and there haven't been any "check engine"lights yet. It will also start if I let it sit for an hour or so sometimes, and then when it does start it blows out smoke and smells like fuel.
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Monday, March 13th, 2017 AT 2:47 PM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
Now when you say "cold starts" do you mean anytime it sits for an extended period of time or when it is cold outside? This may be a coolant sensor out of range. Are all the plugs wet evenly or is it just a few of them that get wet down?
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Monday, March 13th, 2017 AT 2:47 PM (Merged)
Tiny
TILEGUY
  • MEMBER
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Yes, when it sits for a while or overnight, it has this problem. It seems like all the plugs are wet with fuel, some more than others.
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Monday, March 13th, 2017 AT 2:48 PM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
Could be weak spark, or possibly a fuel pressure regulator bleeding into the engine overnight. Check the quality of the spark first, needs to be bright blue out of the coil, if it is more orange it is too weak. Also check the fuel pressure regulator, mounted on the fuel rail with a vacuum line to the intake manifold. If any fuel is present in the vacuum line replace the regulator
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Monday, March 13th, 2017 AT 2:48 PM (Merged)
Tiny
TILEGUY
  • MEMBER
  • 5 POSTS
I have checked the fuel pressure regulator and it seems to be fine, spark is strong and blue in color. I drove it today and then let it sit for about 3 hours and tried to start and am still having problems. The outside temp is 56 so it's not that cold.
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Monday, March 13th, 2017 AT 2:48 PM (Merged)
Tiny
R DOG
  • MEMBER
  • 2 POSTS
  • 1994 ISUZU RODEO
  • 3.2L
  • V6
  • 2WD
  • MANUAL
  • 185 MILES
It was running fine and all of a sudden would not start. I replaced the fuel pump. I checked the fuses. I replaced the relay fuse. When I jump the relay, the fuel pump runs. There is gas in the line at the engine. There is all new plugs and wires. I tried to reset the ecm. I tried a replacement ecm. I started testing wires. The ecm is getting power, but the fuel pump isn't running unless I jump the relay and mnake it run. I am thinking there is a signal loss somewhere in between. Please help. Very frustrated at this point.
Thanks
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Monday, March 13th, 2017 AT 2:48 PM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
Without any codes or a scanner to watch the sensors this could be a tough one to find. It could eba coolant sensor that is out of range and causing the PCM to over-enrich the engine.
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Monday, March 13th, 2017 AT 2:48 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check the relay and where it plugs in if it gets power at the pin to activate the relay it should work.
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Monday, March 13th, 2017 AT 2:48 PM (Merged)
Tiny
TILEGUY
  • MEMBER
  • 5 POSTS
Could it still be the coolant temperature sensor if the gauge is reading correctly? The temp gauge seems to be reading fine. I will have to have it looked at. Thanks for the help.
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Monday, March 13th, 2017 AT 2:48 PM (Merged)
Tiny
R DOG
  • MEMBER
  • 2 POSTS
At the pin? There is 4 wires that go into the plug. The new relay or any other ones do not work when plugged in, however, again, I can jump it and it makes the pump come on.
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Monday, March 13th, 2017 AT 2:48 PM (Merged)

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