Diagnosing Starting Issue - '07 BD TM8

[DeepInTheTrees]

I have an 07 M8 with a Boondocker, race gas, inter-cooled turbo set up (w/BD Box). I have had some of the normal "kinks" through the years, but this one has me pulling my hair out!

Started spring of '10 on a ride. Hillclimb (running 12#) mid-climb it shuts down. I idle down the hill, and it sounds like I smoked the turbo (sounds a little rattly on shutdown). We assumed this is the problem. We end up pulling it out of the canyon we were in by hand, and pulling the charge tube, and exhaust so I could idle back down the trail. About 5 miles later, it died, and wouldn't start. Towed back to truck.

Replaced turbo center section (2860). Went to start up and would barely sputter to life after holding throttle. Assume maybe reeds, as haven't changed yet this year (thought maybe sucked reed petal through damaging turbine). Reeds check out perfect, no issue there. Summer comes.

Pick up again where I left off a few weeks ago (Mid September).

When I pull over it just coughs and backfires.

- Checked compression - Good, 120 both sides
- Continuity tested tail light circuit - good.
- Has spark.
- Checked stator resistance just in case. Good
- Checked coils, visibly all wiring looks good (no wear, etc.)
- Checked grounds - 2 that I know of, BD and stock. Both look good.
- Checked all wiring for visible wear or grounding.
- Swapped injectors from BD set up to stock, no help
- Jumped Aux fuel pump, builds fuel pressure quickly, but doesn't hold well. Dies to 15# in 2-3 secs.
- Pinch off line leaving fuel regulator back to the tank. Pressure holds when I do this. With some throttle it starts and runs! Dies obviously when fuel pressure builds (10-15secs max)
- Sounds like fuel regulator. Borrow one from a friend. Install. Same Issues! No changes.
- Jump stock fuel pump. Works. Run briefly in reverse several times, just in case it has sucked something up. No change.
-After speaking to BD, we deem that there is a remote possibility that this regulator is bad as well (used one that had been sitting for a while...). Replaced with one from my brothers sled (same) that we know works. Same issues!
- Verify voltage at stock pump lead while pulling over. 17 volts. Should be good.

The only way I can get this to start briefly is when I pinch off the fuel line leaving the regulator back to the tank.

I don't believe now that it was the turbine that was my original problem. It is too easy to assume things and jump on them ($$..ouch at least maybe I have a spare )

I'm stuck, and not sure what to do next. Any input from you all would be GREATLY appreciated. Let me know if you have any thoughts.

Thanks!!!

 

[JHG]

I doubt this is the problem but the stator is grounded to the front of the block on the mag side, should be a 10mm bolt. Might be worth checking, other than that try hooking a 9 volt battery to the fuel pump and see if it starts.

You may also want to try unhooking the temp sensor and pulling it a couple times, if it sounds like it wants to start then plug the sensor back in and hold it wide open while you pull it over. If that works then you may have a weak stator coil.

 

[b1dodge]

It sounds like a leak in the tank. You say it will start and run if you plug off the return? And it builds fuel pressure at first and then loses pressure? The pick up is sucking air? Smart valves? Its something in the tank, you are using an external BD fuel pump so all the guts are missing out of the tank right? Its got an issue inside the tank I would bet you a beer.....or the pump is junk....

 

[jensen]

Problem

Could be a broken injector wire. Put a little gas in the intake of the turbo and see if she fires.

 

[DeepInTheTrees]

Great input!

Big Hoe - I have checked that ground on the mag side and all is well. Haven't tried the 9v battery to the fuel pump, but I did "prime" it by using leads to a 18v dewalt battery. Prob. be better to hook the 9v up and actually pull it while under power, I'll try that.
I'll try that temp sensor, my thought has been an eratic or weak stator coil as well, but can't fig out how to prove it without replacement, this could be it.

B1 - That sounds on the right vein as well...everything inside the tank is stock, I just have an add'l external auxiliary fuel pump as well (The stock pump pushes through this external aux. pump, which is how they used to do it, which maybe that is part of the problem?.. What exactly are smart valves and where are they inside the tank?

Jensen - good thought, I'll try it out.

Thanks you guys!! Keep em coming. I'll let you know what I find tomorrow.

-Deep

 

[hatchers]

B1 - That sounds on the right vein as well...everything inside the tank is stock, I just have an add'l external auxiliary fuel pump as well (The stock pump pushes through this external aux. pump, which is how they used to do it, which maybe that is part of the problem?.. What exactly are smart valves and where are they inside the tank?

that old setup was not optimal, most (almost all) have upgraded to what is now known as a single in-tank high volume pump.....you can always hook up 9v and see what going on before you go that route

 

[hatchers]

The only way I can get this to start briefly is when I pinch off the fuel line leaving the regulator back to the tank.

this would also suggest the pump is junk, time for an upgrade

 

[DeepInTheTrees]

this would also suggest the pump is junk, time for an upgrade

I would agree that it is time for an upgrade, but all my tests show that both pumps are good (may still be the problem though...)

Aux pump has power, pumps fuel to pressure when jumped with battery, and holds pressure when fuel line pinched off after regulator (backflow valve good). So this should be fine by all accounts, right?

Stock pump - has 17 volts at recoil pull, when jumped w/battery it pumps to 29-30#(not enough??) when fuel line after regulator pinched and holds pressure. When fuel line not pinched, it dumps off the pressure immediately to like 15#(I'm not sure if it should do this or not, maybe that's my problem right there?)

Do you think I should just order the upgraded pump for the tank and eliminate this possible issue while upgrading? It just doesn't seem like it's the issue though.

I appreciate your input Hatchers! Sometimes I just get frustrated. Glad to have some more stuff to try!

-Deep

 

[product tester]

pull fuel rail off and check injectors for debrei in the top

 

[b1dodge]

Bag both pumps and go to the single intank pump. Having the draw of both pumps never was a good idea. I think one or both of your pumps are junk. The sled should idle at about 38lbs and the regulator should be progressive as boost comes up. sounds like the reg. is fine. All turbo companys have gone to a single walbro fuel pump in tank.

 

[smoothdawg]

Deep in the trees, please post your conlusion to the above issues. Too many times guys find the problem and don't post the results. It's the only way newbies like me are going to learn. Good Luck.

 

[RACINSTATION]

I would say two things, like Product Tester said, pull injectors out and put a white sheet of paper on the bench and tap them on it. You will probably see a bunch of crap in them, also spray with contact or brake cleaner to clean them out. If you are only getting 30lbs you got a pump issue. I fought one a couple years ago that would pump up to about 28 lbs and seemed great as far as draw and was getting proper voltage to run it. The problem is that if your brothers sled is running fine with either pump it kinda rules that out, but I am leaning more toward the pump than anything.

 

[hatchers]

Stock pump - has 17 volts at recoil pull, when jumped w/battery it pumps to 29-30#(not enough??) when fuel line after regulator pinched and holds pressure. When fuel line not pinched, it dumps off the pressure immediately to like 15#(I'm not sure if it should do this or not, maybe that's my problem right there?)

humm, im not sure what pressure should be seen with the two-pump combo......i would get in contact with justin at code red, hes on here

I had a pump start to go bad for 5 or so rides, hard to start, would die 1-4 hours intom each ride and not start again for any duration under 1-2 hrs......its a mother sucker when you pull on a sled for almost an hour, get towed bcak to the trailer, then she starts up fine at the trailer.....took everything i had to not burn her to the ground and drive off

 

[Klimbing Kitty]

I had a pump start to go bad for 5 or so rides, hard to start, would die 1-4 hours intom each ride and not start again for any duration under 1-2 hrs......its a mother sucker when you pull on a sled for almost an hour, get towed bcak to the trailer, then she starts up fine at the trailer.....took everything i had to not burn her to the ground and drive off

X2 been there

 

[harf69]

im running the duel pump setup and at idle you want the same 38psi once the intank pump starts the external takes over and the intank is just free wheelin ford ran there fuel pumps like this for years.One intankl and another on the frame rail external i think the intank ones are cooled by fuel so they may last longer id lean towards injectors myself let us know what you find

 

[DeepInTheTrees]

Thanks for all the help so far you guys! I will let you know what I find. I'm finally getting a chance to dig into it again now. We'll see how she goes.

 

[DeepInTheTrees]

More work checked off the list...

This can get pretty discouraging...

Here is a bunch more stuff I did:

1. Removed fuel rail and injectors. Cleaned thoroughly with carb cleaner. Was some small black “dust” debris in one of the injectors. Don’t think this was the problem though.
2. Put in new plugs, again, just to make sure no issues.
3. Checked spark on all four plugs – looks decent
4. Powered up stock fuel pump with leads from 18v battery while pulling over. When I did this as we were pulling it over; fuel pressure was at about 38#.
5. Powered up secondary pump with leads from 18v battery while pulling over.
6. Ran stock fuel pump backwards again, You can hear pump working fine and fuel dumping back in the tank from the regulator when running forwards.
7. Different CCU
8. Different ECU
9. Different stock injectors
10. Pinched off fuel to secondary injectors (in case they were dumping fuel)
11. Cycled injectors with leads from 18v battery (backwards and forwards)
Dumped some fuel into each cylinder and attempted to start. No luck.
Disconnected hand warmer wires.

It will start up and run sometimes, but only with a lot of throttle upon starting, and it doesn't run very well, as soon as you let go of the throttle, it dies. Lots of smoke like it is getting too much fuel. That is why I started thinking maybe an injector is dumping fuel, but after swapping injectors, doesn't seem to be the case.

I inspected inside the tank closely, as on a prior thread Racin Station had mentioned goldish dust might mean the pump is going bad. I do have some fine stuff on the bottom of my tank, but after putting fuel in the cylinders it should have fired at least for a little bit...

I dunno - Maybe it is the stator getting funky on me even though the continuity numbers looked fine. Don't want to replace one for kicks though.

I appreciate any other thoughts you all might have.

-Deep

 

[Atwitch]

This has been a problem for me once.... problem with tps sensors not letting the sled start! if started it will die shortly after starting! Acts like it wants to start but just wont. usually acts like this from to tight of a throttle cable but possible tps sensor is wacked out!
Here is another idea. U swithced out injectors but did you see if they even would squirt? Pull em out and hold them into the fuel rail and have a friend pull it over 3 times if they dont open then wiring or injectors problems.... just a thought! Had two injectors on the the same sled would not fire this week they both were stuck.

 

[Vertical-Extreme]

Do you have a Hot start switch ? If so is it flipped the right way ? My 2 year old was playing on my sled one day and flipped the the switch and set it to full rich, I started it and filled the case with fuel. It took a lot of pulls with the kill switch off and plugs out to dry it out enough for it to start. If you don't have the switch check your water temp sensor anyways. If it has malfunctioned the sled will be in a full rich mode and will flood out before it can start and run properly.
When it does start are you getting any codes?

 

[dubbs]

Have you checked voltage at the injector connectors? Maybe a bad connection between your stock male injector plugs and your boondocker female plugs?

I would check for voltage right at the injector terminals if you haven't already. Man sounds like you tried almost everything!

Good luck