2008 750 King Quad Stalling Thread - Suzuki ATV Forum
Suzuki KingQuad Discussions for the KingQuad 400,450,750,

 1Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 44 Old 08-18-2017, 07:35 AM Thread Starter
Extreme ATV Enthusiast
 
wizkid00104's Avatar
 
Join Date: Jun 2011
Location: Ross Township, PA
Posts: 274
2008 750 King Quad Stalling Thread

EDIT 9/12/17: Problem turned out to be a sticking throttle position sensor. When the sensor warms up, it doesn't return to the idle position and causing the engine to stall. Read below to see all the tests performed and for how to build a peak voltage detector circuit. Part ordered and replaced.

I have been chasing a stalling issue on my 2008 Suzuki King Quad 750AXi for a while now. I have done a lot of reading and research, so I thought I would put together a thread that combined all that info in hopes it will help someone else. There is a lot of good info on here and I want to thank everyone for their contributions. They have kept me searching.

Details on the machine:
2008 Suzuki King Quad 750 AXi
HMF Performance Slip-On
HMF Fuel Optimizer (Set to factory settings)
NGK CR6EIA-9 Iridium Spark Plug
Factory Air Cleaner
3154 Miles, 409 Hours
Coolant flushed and changed, Oil Changed, Front and Rear Diff Fluids Changed
Warn 2500lb winch, LED Pod Light Bulb, Heat Demon Grips, 126W Light Bar, 2x 27W Work Lights

So this issue started 2 years ago. Quad cut out and wouldn't restart until it cooled. I thought it was the spark plug at first. So I replaced it with the iridium plug: https://www.suzukiatvforums.com/forum...g-upgrade.html

This did not fix the problem. I thought then I didn't seat the boot well and water was getting in the plug. I used dielectric grease and sealed everything up. It still did it.

After reading, I turned to the fuel system. I replaced the fuel filter and did the screen mod on the pressure regulator to bump the pressure a bit: https://www.suzukiatvforums.com/forum...mp-repair.html

I also cleaned the fuel injector. It began to idle much smoother.

It worked fine from here on out. Fast forward to last fall/winter. After coming to a stop, it would just kick off and then it would fire right back up. This was annoying but not really detrimental. And when I used my light bar and work lights they would flicker to the RPM which was annoying. It still had the original battery, so I put a new one in. No change. After some more reading I came to the ground regulator mod: https://www.suzukiatvforums.com/forum...lator-mod.html

It is also related to this issue: https://www.suzukiatvforums.com/forum...dle-issue.html

This boosted my idle voltage to over 14 volts. See the ground regulator mod for my contribution. This solved the random idle stalling issue. While the machine was apart I decided to change coolant, oil, and diff fluids. With all my panels off, this worked great. The quad idled perfectly. I put everything back together and let it idle in my driveway. It idled fine. When I revved the engine, it revved and instead of returning to idle it misfired and died. I've been able to repeat this result several times.

I consulted the factory service manual and some threads on here: https://www.suzukiatvforums.com/forum...ut-10-min.html
https://www.quadcrazy.com/atvforum/t...after-10-mins/

So I started hunting. TPS was in range and I did not have any service codes.

Easiest suspect was that the coil pack was overheating because it sits above the exhaust. I remove it, cleaned all the connections up and replaced with no change. I measured the resistances and they were all in check... 0.1-0.6 primary ohms and 12k-19k secondary ohms. These were measured when the coil was cool. I ordered a new one from Caltric: Suzuki LT-A750X KINGQUAD 750AXI - 2008 - Ignition Coil

It was cheap, but complete. This should at least tell me if the problem was the coil. No one had one in stock nearby.

I installed it and there was no change in the issue. The new coil measure correctly on the primary but I only got 3k ohms on the secondary. I may not have made a good connection but I figured i'd try it. It fired right up and drive great. I let it idle in my driveway and it shut off. I was frustrated to say the least. Time for more reading.

I was following 1H-3 to 1H-6 in the service manual and the troubleshooting codes for C12 (SKP sensor) and C24 (ignition coil) neither of which were displaying since I did not get a check engine light. I checked the resistance of the CKP sensor and it was 220 ohms, right within spec of 150-250 ohms. I did this test while the engine was hot just after cutting out.

Continued.....

2008 KING QUAD 750 AXi CAMO
HMF EFI Optimizer - HMF Performance Series Muffler - Warn 2.5 RT - Highlifter Diamond Plate Bumper
Custom Diamond Plate Toolbox - Front Interco Swamp Lites - Rear ITP Mudlite ATs


Toy Hauler: 2002 F250 Lariat, CCLB, 4x4, 5.4L, 4R100
DD: 1994 Ranger XL, RCSB, 4x4, 2.3L, M5OD-R1

Last edited by wizkid00104; 09-12-2017 at 08:48 AM.
wizkid00104 is offline  
Advertisement
 
post #2 of 44 Old 08-18-2017, 07:45 AM Thread Starter
Extreme ATV Enthusiast
 
wizkid00104's Avatar
 
Join Date: Jun 2011
Location: Ross Township, PA
Posts: 274
The operation is very simple at this point.... CKP sensor tells computer where the crank shaft is. Computer says time to fire spark plug and sends signal to the primary side of the coil. So in my mind, either the CKP sensor is cutting out, or the computer is malfunctioning. In order to do further testing, I need the accessory called "peak voltage detector." Annoyingly, these devices are kind of expensive and of course you can' find the Suzuki on easily. So you can build one: https://thumpertalk.com/forums/topic...ltage-adapter/

I ordered the parts this morning. I got enough to build 3 of them if anyone needs one. PM and we can work something out.

Once I get the parts and build it I will test the CKP sensor cold and see if I get the required 5V or more from the manual. Then I will check the voltage for the primary side of the coil. It should be 80V or more. Then I will run it till it fails and take the readings again. My gut feeling at this point is that my computer is failing. If that is the case hello VDI upgrade

Please note that I have also researched this on the now crappy NYROC site: https://www.nyrocatv.com/tech-tips. See "Stalling" and "Start".

2008 KING QUAD 750 AXi CAMO
HMF EFI Optimizer - HMF Performance Series Muffler - Warn 2.5 RT - Highlifter Diamond Plate Bumper
Custom Diamond Plate Toolbox - Front Interco Swamp Lites - Rear ITP Mudlite ATs


Toy Hauler: 2002 F250 Lariat, CCLB, 4x4, 5.4L, 4R100
DD: 1994 Ranger XL, RCSB, 4x4, 2.3L, M5OD-R1
wizkid00104 is offline  
post #3 of 44 Old 08-18-2017, 08:05 AM Thread Starter
Extreme ATV Enthusiast
 
wizkid00104's Avatar
 
Join Date: Jun 2011
Location: Ross Township, PA
Posts: 274
Here are the coil photos:
Attached Images
File Type: jpg IMG_5729.JPG (1.76 MB, 19 views)
File Type: jpg IMG_5727.JPG (2.46 MB, 14 views)
File Type: jpg IMG_5728.JPG (3.03 MB, 11 views)

2008 KING QUAD 750 AXi CAMO
HMF EFI Optimizer - HMF Performance Series Muffler - Warn 2.5 RT - Highlifter Diamond Plate Bumper
Custom Diamond Plate Toolbox - Front Interco Swamp Lites - Rear ITP Mudlite ATs


Toy Hauler: 2002 F250 Lariat, CCLB, 4x4, 5.4L, 4R100
DD: 1994 Ranger XL, RCSB, 4x4, 2.3L, M5OD-R1
wizkid00104 is offline  
Advertisement
 
post #4 of 44 Old 08-22-2017, 08:01 PM Thread Starter
Extreme ATV Enthusiast
 
wizkid00104's Avatar
 
Join Date: Jun 2011
Location: Ross Township, PA
Posts: 274
I built the peak test circuit tonight. I am waiting on the universal set of probes I ordered so it can be plug and play.

Click the image to open in full size.
Click the image to open in full size.

I bought enough to make 2 more just like you see here. I just need to order more probes. If you interested, PM me and we can work out the details. I should be able to test this one later in the week.


Sent from my iPhone using Tapatalk

2008 KING QUAD 750 AXi CAMO
HMF EFI Optimizer - HMF Performance Series Muffler - Warn 2.5 RT - Highlifter Diamond Plate Bumper
Custom Diamond Plate Toolbox - Front Interco Swamp Lites - Rear ITP Mudlite ATs


Toy Hauler: 2002 F250 Lariat, CCLB, 4x4, 5.4L, 4R100
DD: 1994 Ranger XL, RCSB, 4x4, 2.3L, M5OD-R1

Last edited by wizkid00104; 08-23-2017 at 12:32 PM.
wizkid00104 is offline  
post #5 of 44 Old 08-23-2017, 12:29 PM Thread Starter
Extreme ATV Enthusiast
 
wizkid00104's Avatar
 
Join Date: Jun 2011
Location: Ross Township, PA
Posts: 274
Probes arrived today. I had a little bit of time so I finished up the adapter. I tested it on 120V wall outlet and it seems to work perfectly.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

Just to be clear, in the US 120V is measured in Root Mean Square or RMS. I won't bother going into details, but the actual sine wave is actually more like 166V at peak voltage and that is exactly what this circuit demonstrated.

I have to mow today but hopefully I'll get a chance to test it on the quad later today.


Sent from my iPhone using Tapatalk

2008 KING QUAD 750 AXi CAMO
HMF EFI Optimizer - HMF Performance Series Muffler - Warn 2.5 RT - Highlifter Diamond Plate Bumper
Custom Diamond Plate Toolbox - Front Interco Swamp Lites - Rear ITP Mudlite ATs


Toy Hauler: 2002 F250 Lariat, CCLB, 4x4, 5.4L, 4R100
DD: 1994 Ranger XL, RCSB, 4x4, 2.3L, M5OD-R1

Last edited by wizkid00104; 08-23-2017 at 12:32 PM.
wizkid00104 is offline  
post #6 of 44 Old 08-23-2017, 04:30 PM Thread Starter
Extreme ATV Enthusiast
 
wizkid00104's Avatar
 
Join Date: Jun 2011
Location: Ross Township, PA
Posts: 274
CKP cold and warm both put out a peak of 6.5V. I did not test it at the failing condition yet. I checked the primary coil voltage with the engine running. It should be at least 80V. With the new coil The highest I saw was 25V at idle. I need to swap coils back to the original and try again. I also need to pull the spark plug and just crank the engine as the manual describes. Also, revving the engine increased the voltage to ~30V. This puts them seriously out of spec.

Click the image to open in full size.

More to follow....


Sent from my iPhone using Tapatalk

2008 KING QUAD 750 AXi CAMO
HMF EFI Optimizer - HMF Performance Series Muffler - Warn 2.5 RT - Highlifter Diamond Plate Bumper
Custom Diamond Plate Toolbox - Front Interco Swamp Lites - Rear ITP Mudlite ATs


Toy Hauler: 2002 F250 Lariat, CCLB, 4x4, 5.4L, 4R100
DD: 1994 Ranger XL, RCSB, 4x4, 2.3L, M5OD-R1
wizkid00104 is offline  
post #7 of 44 Old 08-23-2017, 07:48 PM Thread Starter
Extreme ATV Enthusiast
 
wizkid00104's Avatar
 
Join Date: Jun 2011
Location: Ross Township, PA
Posts: 274
Didn't have enough time tonight to do much more testing. I have learned that the 22 uF capacitor is a bit big for testing the spark as it takes a long time to charge up. It may need switched to a smaller capacity so it does not take so long to read the coil primary voltage.

Other than that, I need to swap the original coil pack back in and run the test again tomorrow. I think at this point the problem is the CDI. Hopefully I'll know more tomorrow.

2008 KING QUAD 750 AXi CAMO
HMF EFI Optimizer - HMF Performance Series Muffler - Warn 2.5 RT - Highlifter Diamond Plate Bumper
Custom Diamond Plate Toolbox - Front Interco Swamp Lites - Rear ITP Mudlite ATs


Toy Hauler: 2002 F250 Lariat, CCLB, 4x4, 5.4L, 4R100
DD: 1994 Ranger XL, RCSB, 4x4, 2.3L, M5OD-R1
wizkid00104 is offline  
post #8 of 44 Old 08-25-2017, 10:01 AM Thread Starter
Extreme ATV Enthusiast
 
wizkid00104's Avatar
 
Join Date: Jun 2011
Location: Ross Township, PA
Posts: 274
I contacted VDI with some questions and Lyle replied back later in the day. Here is the reply I received:

Quote:
It’s possible that your peak detector cannot detect the pulses fast enough. The factory ECU will give one 5 degree spark every 720 degrees of rotation (so quite short in the overall scheme of things). If the capacitor in your peak detector is too large, it will average out the reading, showing a much lower reading. Our ECU will give a constant 170V peak to peak regardless of RPM/cranking.

A couple things that could be issues though:
  • Bad rectifier. If you unplug the rectifier, will it run fine and not stall (it won’t charge at this time, so the battery voltage will continue to drop).
  • Low fuel pressure. The ECU expects 42 to 43PSI of fuel pressure at the injector with key on, or running.
  • Bad ground to the engine block. There should be zero ohms resistance between one of the coil terminals and the negative battery terminal, as well as the engine block to the negative battery terminal.
  • Bad thermostat. When it gets hot, is the radiator hot? If it’s still cool then water isn’t leaving the engine and the fan won’t operate correctly.

It is possible that the ECU is failing (as it gets hotter, it would be more prone to losing spark). Immediately after it stalls, can you measure voltage on the coil? If there is no voltage (or much lower than running), I’d suspect the ECU is bad.
I didn't suspect the rectifier causing a problem... but it is possible. I'll have to check it when heated up. my fuel pressure was good, but I can recheck it to make sure. I think the engine ground is good since I just redid it, but I can use the multi-meter and check resistance. I think my thermostat is OK since my fan does turn on and off.

The ECU failing in the heat still seems most likely to me, but a little more testing should confirm it.

In regards to the highlight section about the factory spark... The engine idles at about 1350 rpm. Divide this by 60 seconds to get 22.5 rotations per second. If you take the inverse of this (1/22.5) you get 0.044 seconds per rotation. We know that the engine only sparks for 5 degrees out of 360 degrees (1.389%) in the rotation, which means out of the 0.044 seconds in a rotation, spark occurs for .044 * (5/360) = 0.000611 seconds... So each spark takes 0.000611 seconds and if you extrapolate that up to RPM you get 0.000611 seconds * 1350 rpm / 2 (because it is a 4 stroke engine) = 0.412425 seconds of spark in a 1 minute period.

I did some iCircuit analysis to see if the designed tester would work and it did on paper. Knowing this now, I will need to crunch some more numbers and see if it can detect the spark accurately.
Attached Images
File Type: png IMG_5837.PNG (80.8 KB, 5 views)
File Type: png IMG_5836.PNG (94.1 KB, 4 views)

2008 KING QUAD 750 AXi CAMO
HMF EFI Optimizer - HMF Performance Series Muffler - Warn 2.5 RT - Highlifter Diamond Plate Bumper
Custom Diamond Plate Toolbox - Front Interco Swamp Lites - Rear ITP Mudlite ATs


Toy Hauler: 2002 F250 Lariat, CCLB, 4x4, 5.4L, 4R100
DD: 1994 Ranger XL, RCSB, 4x4, 2.3L, M5OD-R1
wizkid00104 is offline  
post #9 of 44 Old 08-25-2017, 12:48 PM Thread Starter
Extreme ATV Enthusiast
 
wizkid00104's Avatar
 
Join Date: Jun 2011
Location: Ross Township, PA
Posts: 274
Did some more reading...
http://www.electronics-tutorials.ws/rc/rc_1.html
Capacitor charge and discharge calculator | MustCalculate

I decided to order new capacitors and bleed resistors. Changing from 22uF to 0.47uF and 1Mohm to 47Mohm.

Time Constant as-is (R=300 ohms and C = 22uF) = 0.0066 seconds. Multiply by 5 for fully charged capacitor = 0.033 seconds.
Current spark duration = 0.000611 seconds


As you can see, the time constant is magnitudes of order larger than the spark at idle. A small capacitor is needed to get a more accurate and quicker value.

New Time Constant (R=300 ohms and C = 0.47uF) = 0.000141 seconds. Multiply by 5 for fully charged capacitor = 0.000705 seconds.
Current spark duration = 0.000611 seconds


As for the bleed resistor, it would take approximately 15 seconds for voltage to halve itself at 22uF and 1Mohm. To keep with that same rate with the new 0.47uF capacitor, the resistor has been upped to 47Mohm.

This new configuration should give a much better reading when testing spark peak voltage. We shall see when the parts arrive next week.

2008 KING QUAD 750 AXi CAMO
HMF EFI Optimizer - HMF Performance Series Muffler - Warn 2.5 RT - Highlifter Diamond Plate Bumper
Custom Diamond Plate Toolbox - Front Interco Swamp Lites - Rear ITP Mudlite ATs


Toy Hauler: 2002 F250 Lariat, CCLB, 4x4, 5.4L, 4R100
DD: 1994 Ranger XL, RCSB, 4x4, 2.3L, M5OD-R1
wizkid00104 is offline  
post #10 of 44 Old 08-25-2017, 06:12 PM Thread Starter
Extreme ATV Enthusiast
 
wizkid00104's Avatar
 
Join Date: Jun 2011
Location: Ross Township, PA
Posts: 274
Got the engine to the stalling point after swapping the factory coil back in. Idle voltage on factory coil was reading about 39V and went down just a tiny bit at the stalling point. I'm hoping to get better reading with the new circuit parts.

Checked the CKP and still got good readings when the quad wouldn't start.

I temped the voltage regulator. I had no idea it got to 200 degrees. I pulled the plug and tried to start the engine with no change. And battery was reading 14V when it stalled so I am fairly certain it's not the regulator.

Check grounds and they all looked good including the ground to the coil.

The CDI/ECM was cool except for a warm spot on the back which was about 100 degrees. I thought it would be warmer but it stays pretty cool since the fuel tank is underneath it.


Sent from my iPhone using Tapatalk

2008 KING QUAD 750 AXi CAMO
HMF EFI Optimizer - HMF Performance Series Muffler - Warn 2.5 RT - Highlifter Diamond Plate Bumper
Custom Diamond Plate Toolbox - Front Interco Swamp Lites - Rear ITP Mudlite ATs


Toy Hauler: 2002 F250 Lariat, CCLB, 4x4, 5.4L, 4R100
DD: 1994 Ranger XL, RCSB, 4x4, 2.3L, M5OD-R1
wizkid00104 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Suzuki ATV Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
07 King Quad keeps stalling otto.hooper Suzuki KingQuad 2 03-26-2017 08:46 PM
Lt4wd 250 and lt4wd 300 King quad tire size question. herbertv2 Wheels & Tires 2 03-10-2017 12:54 PM
2008 king 750 stalling when hot ripley Suzuki KingQuad 14 03-17-2016 11:39 AM
New 2016 King Quad Millst0ne New Member Introductions 66 02-17-2016 04:58 AM
Suzuki Spark Plug Chart (NGK) ajl719 Repair and Maintenance 2 07-07-2011 10:41 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome