2001 Isuzu Trooper Intermittent Hard Start/Crank No start

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2001 Isuzu Trooper Intermittent Hard Start/Crank No start

Postby willpahle » Mon Apr 13, 2020 6:56 am

Hi all:
New to the site. I recently acquired a ‘01 Trooper 3.5l with a whopping 367,000 miles. Original owner had a full long block rebuild professionally done at approximately 320,000. Truck had served him well up to this point and now I have acquired it. Vehicle doesn’t burn oil or consume coolant. No check engine lights. Aside from the starting issue I have, the vehicle runs fantastic.

After driving the vehicle for around 5 days with no issues, it began to develop a hard start/misfire on cold starts or similar symptoms after the vehicle has sat for 45 minutes or longer. I have practically pulled hair in efforts to self troubleshoot, but I’m now reaching out to resources for hopefully some conclusions. Here are the facts and the things I’ve done so far;
-New ICM
-New fuel filter
-New Cam sensor
-New spark plugs
-Relays and fuses checked
-Fuel Rail pressure checked at 41 before start and 36 running
-Battery voltage checked
-Injectors ultrasonically cleaned and bench tested
-Coils tested with test light for functionality during cranking
-Removed throttle body and cleaned small amount of build up off of assy.
-Verified resistance on coolant temp sensor

Any of yours input would be greatly appreciated.
Thanks,
Will
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby Buster28 » Tue Apr 14, 2020 11:01 am

Check the MAP sensor port and ensure it is not plugged with carbon. If you have a live data scan tool monitor the MAP sensor and IAT sensor signals and ensure the values are within the expected range.
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby willpahle » Wed Apr 15, 2020 6:27 pm

Thanks for the response buster! I pulled off the MAP sensor and probed the port with a narrow screwdriver, but didn’t find any build up. I cleaned off a little oil residue on the sensor port end and placed back on the manifold. I’m waiting on a tool in the mail to hopefully verify the map and iat parameters that you mentioned. Quite frustrating, since i know when the vehicle does start, it runs great..
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby GrayTroop » Sat May 02, 2020 8:11 am

Hey did this work? I have an 02 that stalls at stops and I'm wondering if it's the map sensor
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby muddingrodeo » Mon May 04, 2020 11:08 pm

Check the CKP sensor.
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby willpahle » Mon May 04, 2020 11:42 pm

Where is the ckp sensor on the 3.5l V6? I’ve looked at a few different schematics, but none of them reference the exact location.
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby muddingrodeo » Tue May 05, 2020 12:19 am

Passengers side below the exhaust manifold next to the motor mount.
98 Isuzu rodeo 4x4 4" lift 32" tires all black ( mudding truck)
98 Isuzu trooper 4x4 4" lift (fixing transmission)( got this one fixed finally and running on 33" tires)
02 Isuzu trooper 4x4 parts car(may fix up)(my kid wanted this one so its being fixed) Update! this one is now fixed non mudder
98 white Isuzu Trooper 4x4 supposed to be parts car ( having trouble sticking to this idea!)
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby Buster28 » Tue May 05, 2020 6:01 am

willpahle wrote:Where is the ckp sensor on the 3.5l V6? I’ve looked at a few different schematics, but none of them reference the exact location.

The CKP is the Crankshaft Position Sensor, if it is defective the engine won't start/run.
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby willpahle » Tue May 05, 2020 6:20 am

So the CKP sensor wouldn’t be intermittent? It’s either toast or it’s functioning? I still haven’t gotten the obd tool i ordered off amazon, so I haven’t been able to observe the map sensor or coolant sensor permaters.
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby Buster28 » Tue May 05, 2020 9:02 am

It is remotely possible the Crankshaft Position Sensor could fail intermittently preventing engine start. Replace it and see if the problem is resolved.
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby willpahle » Mon Oct 26, 2020 6:46 am

*Update*
Since last posting, have had leak down test performed with no findings.
Replaced FPR
Replaced start switch harness

Trooper is still cranking and missing for long periods of time and sometimes simply won’t start.
There is no consistency to when the truck will or will not start.
Pretty puzzled at this point, and will take any recommendations or advice.
Thanks
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby Buster28 » Mon Oct 26, 2020 7:50 am

The Fuel Pump is controlled by the Fuel Pump Relay which in turn is controlled by the Powertrain Control Module (PCM). When the Ignition Switch is initially placed in the Run ("On") position the PCM energizes the Fuel Pump Relay for a few seconds to pressurize the fuel rail for start up. If the Fuel Pump Relay fails to operate there is no fuel to start the engine because the pressure bleeds down to zero when the engine is not running.

To test the Fuel Pump Relay, connect a fuel pressure gauge to the fuel rail test port and place the Ignition Switch to Run for 10 seconds and back to Off without cranking the engine. The expected fuel pressure is about 40psi and should remain close to this pressure for several minutes after the Ignition switch is placed in Off. If there is no pressure or the pressure bleeds to zero quickly there is a problem. Run the test several days in a row and check for consistent results. It is also possible the Fuel Pump is failing.
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby willpahle » Mon Oct 26, 2020 8:20 am

Hi Buster:
Thanks again for responding it such a quick manner.
Would it be possible that it’s the fuel pump even if there is a strong presence of gas odor at the tailpipe during the hard starts ? I have pulled plugs on a few occasions when the vehicle is unable to start and they are always very wet, and even after only a hundred miles or so on the plugs, the electrodes were a darker brownish color.
Around 4 months ago I had done a fuel rail pressure check and was seeing around 37psi consistently, and would hold pressure for about 5 minutes before slowly dropping off. Hope this information assists your thought process.
Thanks again
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby Buster28 » Mon Oct 26, 2020 9:08 am

If the plugs are wet it strongly suggests there may be an ignition problem. Buy some starter fluid and the next it won't start in the first couple of cranks try the starter fluid. If if doesn't try to start there must be an ignition problem.
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby willpahle » Mon Oct 26, 2020 7:06 pm

Tried started fluid and was only getting more emphasized back firing through intake. At some point 3-4 months ago I had performed a very basic visual check on spark for each coil, but don’t know if the spark was strong or not. Simply was only able to verify that each plug was sparking.
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby Oro » Tue Oct 27, 2020 12:29 am

I didn't see where you ruled out the crank sensor definitively?

It would have been something I checked out much earlier. I have had this issue with other vehicles - not on my Trooper though.
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby willpahle » Tue Oct 27, 2020 1:35 am

Yeah, buster had mentioned replacing the CPK before as well, since I’ve read that it can have a major impact on ignition, I think it would be a wise next step. Will update when I get it replaced and can determine effect.
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby Buster28 » Tue Oct 27, 2020 6:28 am

If the spark plugs get wet with fuel the injectors must be being pulsed. This suggests that Crankshaft Position Sensor is generating the 58x pulses necessary for the PCM to pulse the injectors. Use this OTC 7602 NOID to verify the injector pulses.
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby willpahle » Tue Oct 27, 2020 9:16 am

Okay, great! Got one on order and should have it in a few days. Does the Crank position sensor mainly affect injector operation or does it also have an affect on ignition? Thank you again for your help!
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby Buster28 » Tue Oct 27, 2020 12:12 pm

This is what makes the Crankshaft Position Sensor generate the 58x pulses, note the two missing teeth at the arrow head, this is the beginning and end of the sequence and how the PCM knows when to pulse the injectors and spark plugs. The Camshaft Position Sensor function is built into the Ion Sensing Ignition module.

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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby willpahle » Sat Oct 31, 2020 6:36 pm

Crank sensor replaced and made no improvement on starting. I received the anode in mail and will test the injector harnesses for proper pulse signal.
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby willpahle » Thu Nov 05, 2020 3:44 pm

I have another question. Does the fuel pump relay in these Suzuki’s control the fuel delivery during the initial 5-10 seconds of start up? I have a buddy who’s been into Honda’s for years and the 90’s era Civics have fuel pump relays that if they go bad will cause starting issues since it affects fuel delivery.
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Re: 2001 Isuzu Trooper Intermittent Hard Start/Crank No star

Postby Buster28 » Thu Nov 05, 2020 5:05 pm

The Fuel Pump Relay is the electrical switching device that connects the Fuel Pump to the +12 Vdc source. If the relay fails to operate the Fuel Pump will never run at all.
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