RUNAWAY DIESEL! - page 1 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• RUNAWAY DIESEL! by sdwarf36 on 25 Mar, 2012 17:12
• Yikes! That was scary! Now I need to figure out why-no its not a sucked turbo seal-its in the pump.
   Background: rebuilt engine with 7k miles on it-t3 turbo-Giles pump-running on veg (for the last 110k miles).
   was driving down the hiway 70 mph-come to a hill-making 5 or so psi boost 800 or so egt. The veg filter was getting plugged-I felt it buck so i switched over to diesel-and it ran away. Managed to stall it as all the termoil was going on-key wasn't killing it at 1st-must have dumpped tons of fuel while making 25psi. (in further troubleshooting after cooling it would kill it though )
   Things I've figured so far:
   Its not in the oiling-the level is normal and in refireing it, there was nothing pouring out the breather-the air filter isn't oiled up.
   Its in the pump-if the shutoff wire is pulled while its reving, it will die.
   I can start the car-within 2 seconds it runs away-gas pedal has no affect. I can start-rev-shut off the key-let the rpm drop+ turn the key back on + it revs again.
   
  I called someone that knows the pumps better than me-and one thing he thought-in trying to get my Giles pump "tuned down" to not pump tons of smoke, I have the screw on my LDA backed way out-maybe 7 threads or so showing.
  
  So I guess my question is this-Is there anything you could think that in a situation where the IP is sucking hard for fuel and than all of a sudden get some-cause something in the pump to come unhooked and acting like its under full throttle due to adjustments cranked too far?
• #1 by chrisg on 25 Mar, 2012 18:29
• this happened to me kinda...
  
  does it shut off with the key now? i was coming home from work one day and all the sudden she just went WOT out of know where. i could kill it with the key, but if i turned it back on it would instantly go WOT. i got a new pump and all was solved
• #2 by theman53 on 25 Mar, 2012 19:29
• The pump will not like to run 7 turns out. Which pump to you have and could you take a pick of it? Sounds like some of your home brew may have gunked up the insides...governor specifically. You might want to get some diesel purge or ATF and let it sit in it???
  
  I had all sorts of plans to run Veg but after spending so much on my pump I couldn't bear to. Good luck.
• #3 by 8v-of-fury on 25 Mar, 2012 19:33
• I agree Lucas, it would seem as though you have funked up your internal throttle. They get reallllly nasty inside when you run Veggie Oil.
  
  
• #4 by sdwarf36 on 25 Mar, 2012 20:25
• I'm open to all suggestions, but this is a fresh pump with 7k on it. I had no problems in over 100k and 4 years of veg on my old engine/ pump. Is there anything in a rebuilt pump that would gum up differently?
• #5 by 8v-of-fury on 25 Mar, 2012 20:26
• Maybe this particular time the veg oil was not quite warm enough???
• #6 by belchfire on 25 Mar, 2012 20:40
• Surprisingly enough the same exact thing happened to me yesterday and today. Minding my own business going down the freeway when a horrible bang and enough smoke to cloud both sides of the road. Engine ran away and I got it stopped by braking in 5th. Started it back up & same thing. I pulled the breather hose and it fired up OK. Ran OK the rest of the way home and to work this morning. !/2 way home I passed some jerk at wot and then settled back down for a mile or so when Bang & smoke. I just kept it going & it cleared up. Now it runs better??. I just rebuilt the thing after a cam belt jump & was disappointed that I still had what sounds like piston slap. It ran great except for the noise. I had a no hot start issue but attributed it to the bent valves and off timing. Still had the issue after the rebuild. I was planning on pulling the pump tonight but after the last bang, things cleared up. The knock is mostly gone and it fires right up hot. Tomorrow will tell if this is the fluke. BTW, just like you I'm running SVO. Been doing it for 4 years and 30K miles but this is the first run away that I've experienced. If this doesn't magically resolve itself, then it's probably back to the shop & another $600. I had suspicions of charge pump cavitation & subsequent erosion and was thinking that that may be the hot start issue. If it comes to that and that's the case, then I will certainly post my findings.
• #7 by 92EcoDiesel Jetta on 25 Mar, 2012 21:18
• Was  the runway a 1 time thing or is it doing it consistently? 
  Have you messed with the fuel screw? Where is it set at?
• #8 by sdwarf36 on 25 Mar, 2012 21:21
• Quote from: 8v-of-fury on 25 Mar, 2012 20:26

  Maybe this particular time the veg oil was not quite warm enough???
  

  I was 1/2 hour into the trip-oil was in the 130's. The throttle position was between 1/4 + 1/2 when it happened-it wasn't a case where I stuffed the gas + it stayed.
• #9 by sdwarf36 on 25 Mar, 2012 21:33
• Fuel screw has been played with many many times. Everything is turned down from where is was delivered. (I've been bothered by how much smoke it produces-I've sacrificed power for socially acceptible amounts of smoke) Nothing has been changed over the last 1000 miles. Residule screw (idle) was turned down untill it just about stalls-main fuel screw in till it just picks up the idle speed- maybe 1/4 turn. LDA screw backed way out. Just a litle poof of smoke if I push the pedal down some from 5 psi boost-good cloud if i go 3/4 thottle quickly + go over 12psi or so.
• #10 by 92EcoDiesel Jetta on 26 Mar, 2012 05:55
• " I can start the car-within 2 seconds it runs away-gas pedal has no affect. I can start-rev-shut off the key-let the rpm drop+ turn the key back on + it revs again."
  
  Is this happening consistently? How are you filtering your veg? Take some parts off the pump  and look for signs of vo gunk with a magnifier. if you find gunk, I can suggest some non invasive ways of cleaning.
• #11 by 92EcoDiesel Jetta on 26 Mar, 2012 06:23
• "I can start the car-within 2 seconds it runs away-gas pedal has no affect. I can start-rev-shut off the key-let the rpm drop+ turn the key back on + it revs again."
  
  if I am reading this correctly, it sounds like your fuel shut off solenoid is not cutting fuel to the pump quickly and totally. I would suggest taking off the fss  and cleaning it.
• #12 by rallydiesel on 26 Mar, 2012 09:24
• All bets are off when you run waste oil. Especially on a performance pump where precision calibration and fuel viscosity and fuel temp play very important roles.
• #13 by belchfire on 26 Mar, 2012 14:00
• FSS has nothing to do with it. Even if it were non functioning, you would still have full throttle control. You just couldn't turn it off. Mine seems to run fine after the incident. My "bad " engine befrore the rebuild had a lot of slimey crud in the breather hose. I cleaned it out the best I could but the "valve" on the cam cover is sealed. After the incident I un-sealed it and it still had some residual crud in it. I'm thinking that some of it worked loose and fed the engine a bunch of "fuel". This made the smoke & noise & subsequent running away. Eventually cleared & back to normal. How does your hose look? Does it run normal with it removed?
• #14 by 745 turbogreasel on 26 Mar, 2012 15:27
• $0.02 says Control collar stuck on its shaft.
  Using hydrogenated oil by any chance?