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08 700 dragon injectors not opening

C

Chevy3500

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Dec 7, 2010
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Working on an 08 700 dragon...have good spark and compression...no fuel.
New fuel pump and filter...good fuel pressure at the shrader valve...returning fuel fine...tried a new regulator...a different ecu
I can make sled run and idle if I manually spray fuel in the throttle boddies...need help!
Thanks in advanced
 
C

Chevy3500

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Dec 7, 2010
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Which set of injectors are the main ones?
Resistance of stator is .05 ohm at 15 degree f.
 

sled_guy

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Jul 5, 2001
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Not sure of your question on the main injectors. There are 2 sets, upper and lower. But only one set runs at a time. If you look closely at the injectors, right by them on the harness, there is a little tag that tells you PTOU, PTOL, MAGU, MAGL.

Once you find a couple of them then the wiring holds them in position so the other falls in to location where it should be.

sled_guy
 

89sandman

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Have you checked to see if the injectors are strobing? When you pull the rope you should get around 12 volts to the injectors and it should go on and off when the ecu grounds the circuit to make them fire.
 
V

volcano buster

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Nov 26, 2007
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I made a setup for my CFI-4 recently.

- I had the injectors out (engine on bench getting new top end)
- On this vintage the injectors are still on the wiring loom to the ECM
- I was able to hook the fuel lines to the fuel rail
- I made a wooden block for each pair of injectors and zip tied it to hold the injectors in the loom
- I used a large 12v transformer to power the fuel pump with a switch
- I installed a momentary "on" switch to a 2-wire pig tail.
- I soldered a short piece of .023" welding wire to each lead tip
- I was able to disconnect harness from ECM and identify which ports were for the injectors
- I carefully inserted the .023" leads into a (+) and (-) for each injector
- I pressurized the rail with the tank pump then triggered each injector to ensure they responded.

I didn't take any pictures apparently.
 
C

Chevy3500

New member
Dec 7, 2010
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Not sure of your question on the main injectors. There are 2 sets, upper and lower. But only one set runs at a time. If you look closely at the injectors, right by them on the harness, there is a little tag that tells you PTOU, PTOL, MAGU, MAGL.

Once you find a couple of them then the wiring holds them in position so the other falls in to location where it should be.

sled_guy

Thanks for the reply...I know there are 2 sets...just wondering if it the upper or lowers that have the full load on them..which set starts it??
 
C

Chevy3500

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Dec 7, 2010
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Have you checked to see if the injectors are strobing? When you pull the rope you should get around 12 volts to the injectors and it should go on and off when the ecu grounds the circuit to make them fire.

I have not checked that...I did however cut the upper pto injector out of loom and checked to see if it "strobed" with a 9v battery...it did and I ran some carb cleaner through it...also checked for continuity from ecu plug to where I cut injector wire...I cut it after the splice where the two uppers are splices..that is good...

Maybe it's a bad ground??? U said the injectors fire when ecu grounds circuit??
 
T
Nov 29, 2010
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same problem here. 2008 dragon 700. Ran fine. Pulled motor for some repairs. Put back in and now have the same problem you have.
 

slash

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all injectors require a pos signal the ECU/M controls pulse width(time injector is on)by activating ground MAKE SURE ALL YOUR GROUNDS ARE CLEAN AND TIGHT .
 

sledhed

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I basically went through a similar problem, and I threw parts at it from friends until I basically narrowed my problem down to wiring harness or injectors, here is the thread from my ordeal last year (sled is running great this year as well as at the end of last season once I got it going):
http://www.snowest.com/forum/showthread.php?t=392726&highlight=860

I did stator, full engine compartment harness, ECU / ECM, capacitors (2 including the one in the harness), fuel pump, several fuel filters, direct voltage to fuel pump, pressure tested fuel system, stator and flywheel (stator supplies current directly for the injectors through the ECM)... buying a complete used fuel injector harness (off ebay) with injectors attached of the right color (and for an 800) got my sled up and running again, I still suspect it was the big connector into the ECU / ECM but no way to know for sure, I kept the "bad" harness and injectors for spares since they could be replaced one at a time if necessary.

So no guarantee it is the same problem, if you have a buddy who will switch parts with you off of his sled to test them that is helpful, otherwise it might be a little pricey trial and error (you can buy used off ebay like I did for some of them but there is always a chance the part you bought has an issue and that plays mind games with you). The last thing I changed that fixed it for me was the injector harness with injectors, I ended up putting everything else back and giving the loaner parts back. Cost me quite a bit of time out of my season to troubleshoot... if you were close I would loan you some of my spare parts to test everything out with...
 
C

Chevy3500

New member
Dec 7, 2010
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I basically went through a similar problem, and I threw parts at it from friends until I basically narrowed my problem down to wiring harness or injectors, here is the thread from my ordeal last year (sled is running great this year as well as at the end of last season once I got it going):
http://www.snowest.com/forum/showthread.php?t=392726&highlight=860

I did stator, full engine compartment harness, ECU / ECM, capacitors (2 including the one in the harness), fuel pump, several fuel filters, direct voltage to fuel pump, pressure tested fuel system, stator and flywheel (stator supplies current directly for the injectors through the ECM)... buying a complete used fuel injector harness (off ebay) with injectors attached of the right color (and for an 800) got my sled up and running again, I still suspect it was the big connector into the ECU / ECM but no way to know for sure, I kept the "bad" harness and injectors for spares since they could be replaced one at a time if necessary.

So no guarantee it is the same problem, if you have a buddy who will switch parts with you off of his sled to test them that is helpful, otherwise it might be a little pricey trial and error (you can buy used off ebay like I did for some of them but there is always a chance the part you bought has an issue and that plays mind games with you). The last thing I changed that fixed it for me was the injector harness with injectors, I ended up putting everything else back and giving the loaner parts back. Cost me quite a bit of time out of my season to troubleshoot... if you were close I would loan you some of my spare parts to test everything out with...


Thanks for the link...did you ever test the old injector harness to identify the problem?
 

sledhed

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Thanks for the link...did you ever test the old injector harness to identify the problem?
Welcome! I know what a pain it was to diagnose so I wanted to share in case it helps.

I did not test the old harness and injectors, however before I went through the trouble of putting in the new injectors and harness (since it is a genuine pain to get the lower injectors in without removing the motor but I did it), I hooked them up and basically pressurized each injector with some WD-40 (idea I found off snowest forums), pulled the engine over, and watched the spray come out of the injectors. I tested whichever injectors are start and low-speed (I forget which pair, upper or lower) since those were the no-start problem. Then I installed the harness and injectors and everything else (a lot of it still hanging loose but hooked up)...
 
C

Chevy3500

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Dec 7, 2010
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Everything for the stator is within specs as far as resistance except for the brown with white stripe..can not get that one to ohm out. It is a ground, but what do I touch the other multimeter tip to?
I have tried engine, chassis, and the ground behind the ecu...cannot get the gauge to move
 

sledhed

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Everything for the stator is within specs as far as resistance except for the brown with white stripe..can not get that one to ohm out. It is a ground, but what do I touch the other multimeter tip to?
I have tried engine, chassis, and the ground behind the ecu...cannot get the gauge to move
I believe I had that issue too but it was not a problem... I am at work now but check back in that thread, either in that thread or in emails with a Dragon owning friend of mine (don't recall which) I encountered that same issue, but since the stator change-out did not fix my sled it was a red herring. PM me back to remind me and I will check to see where i found that info - the ground comes back through the harness ground if I recall but like I said I don't recall for sure...
 

slash

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the ECU/M does the grounding but it needs a good ground to make ground . Get a wire diagram test the wires end to end OHMs . Then load test the wires to make sure there good solder a 1056 bulb in the center of a test wire ground the harness or the test lead use a 9V for power UNPLUG ECU/M first just test the wire harness end to end to make sure it's good .......sorry it's hard to explain thats second nature 35 years as a auto mech.
 
C

Chevy3500

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Dec 7, 2010
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Traced the injector wires to the plug..took a t50 staple and straightened it and inserted into plug where injector wires come in.
I used 2 staples. One for pos and one for neg.
Took a 9v battery and touched the staples...I could here the injector click.
Did all 4 that way...all worked
 
C

Chevy3500

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I can pressure up fuel rail and activate each injector separately...each one sprays
 
T
Nov 29, 2010
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Laid the used injectors/harness over motor plugged in. With a little fuel in the rail and some pressure it is flowing fuel out of the lower injectors.
 

sledhed

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Sounds like you guys may have a different problem than I did. The stator does generate the current for the injectors independent of the other charging circuits if I recall correctly (I forget which color wires are involved in powering the injectors, it is pretty clear in the service manuals, I have a PDF of the service manuals), even if the stator ohm's out correctly it could still be the stator. Also the flywheels have been known to have magnets get loose but I suppose that would cause damage pretty quickly.

I wish you good luck, frustrating issue when it comes up for sure...
 
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