Another set of twins.

[HVAC]

>What do you meen, vapor locked?



I think that's self explanatory. Have you not heard of a gas engine vapor locking?



>What causes it?



Side stepping the throttle.



>and why have I never heard of it in a diesel before?



Because your a rookie and you don't know everything.



>What can I do so it doesn't happen again?



Make sure your fuel system is in as good a shape as possible. And don't side step the accelerator.



Have you gotten rid of the banjo bolts? When did you check the lift pump last? Are you running stock fuel lines in the engine compartment?



Jon T

 

[Jim Fulmer]

Nowell, that is some good stuff that I did not know about the VP pump, Jon E-mailed me about the oil problem and I thought he might be sucking oil from the turbo with the BHAF and the minder(whatever) pulling all the way down. Mark K. warned me about this so I went with the big AFE filter and do not have any oil problems to date, Good stuff on this thread!



Jim

 

[csutton7]

ah yes the ol vapor lock--makes for interesting and sometimes embarassing times---just like HVAC said you can't just let up abruptly on the throttle at the end of a hard run--ease off of it------chris

 

[JTroiano]

HVAC, I hope you didn't take my last post as a slam. I was just a little frustrated. Yes I am rookie. I thank you for the info. I truly apprecaite it. I just wish it was a day earlier.



I don't have a BHAF any more, I put on a K&N that is 18"x7 1/2" and has an opening of 6". I used 5" tubing. I did check the oil a couple of days ago and it was a little low.



I will put a picture up as soon as I get all the bolts back in.



Got to start work so a can pay for my habit.



Jon T

 

[HVAC]

No Worries

The truck is running now and it's all good



I would add that this vapor locking usually is only going to occur on a truck with a serious fueling box, big injectors, etc. Kick it into nuetral or just let off the throttle slowly. We actually do our burn out without the fuel box on to try to prevent this phenomenon. A good example of how to avoid the vapor lock problem is seen on the video of us running 12. 3 at Sears Point. We are in the right lane and lil Adam does his burnout and then slowly gets off the throttla and lets it come up to the line.



BTW, I recall Lawrence saying not to bleed the #1 line from the pump. I'm looking in the manual now to double check that. I usuall catch 3, 4, & 5.

 

[JTroiano]

Thanks, you mean you catch 3,4 and 5th gear?



Jon T

 

[CMNS PWR]

Sounds like injectors 3, 4, and 5.

 

[HVAC]

Yup,

I was referring to 3, 4, & 5 injector lines. Then give it some pedal when you crank it to increase fuel flow. One or two injectors will start firing and once it's lit I hold the rpm up as say 1500-1800 till it clears out.

 

[Roger rodbolt]

Works for me

I bleed #3 and 4 injector when necessary but always carry a can of starting fluid with me. Let the truck sit five minutes, take the intake air hose off, make sure the grid heater won't cycle and run the engine on starting fluid for an instant. It will reprime and run rough while the air works itself out. Don't have to crack a line, I have it happen several times. Larry

 

[JTroiano]

HVAC, thanks for the info. . The first thing I checked when it died was that I had fuel into the VP and then I loosened the #1 injector and cranked it and didn't get any fuel and I didn't check any others.

I've been in the car business for 22 years and worked on heavy equipment for my father a little but never heard of this type of fuel problem. Oh ya my memory is coming back I started working on cars when the the old rocket 350 was made into diesel. Oh ya and the 6. 2 Chevy's that had a million head gasket problems. Need to forget those days.



So is it the fuel cavitating or is there pressure going back in through the injectors??



Jon T



Guess I'll have to start carrying a wrench set with me because it is to much fun to not use all the power.

 

[HVAC]

Ether

What Roger Rodbolt suggested is a good idea also. Ether is used by some folks in this situation. Just be damned sure you are working on a hot engine and the grid heaters are for SURE NOT going to be coming on. The grid heaters will ignite the ether and create kinda a hot foot for ya.



JT, I don't really know exactly what is going on in the engine to create this problem. I stated you need a highly fueled engine for this to develop. My thought is that you go from max fuel where everything is moving at a thousand miles and hour to 0 % throttle which is like slamming a valve closed at the pump. In this case I imagine the fuel pressure dropping dramatically in the system between the pump and the injectors to the point of vapor introduction. Ever see a agricultural sprinkler system when the pump is first turned on? The sprinklers don't sprinkle, they just pisss. It's worse for us cause the injectors won't even fire till the pressure is 4500 psi. Now assuming the pump is working normally, we still have vapor in the high pressure injector lines. And as you all know, vapor will compress will little pressure appreciation. So we are cranking on the starter and the pump is doing it's thing, however all that is happening is the vapor trapped within the high pressure line is functioning like a spring and absorbing the pulse from the injection pump without the injector firing.



This is just my take.

 

[JTroiano]

Well I got it all back together tonight and bought a cheap oil pressure gauge and I have good oil pressure. I still had a few pieces off the truck so that is maybe why it wasn't working and it was only down about two qaurrts of oil. I also have the oil pressure idiot light hooked up. But I had to disconnect the one from the wastegate. I took it for a ride and all seems good. I got it nice and warm and hit it pretty hard again and tried to not let off to quick and it was OK. I think the VP pump looks pretty good inside and I would take one apart again. They are not to hard once you know how they come apart.



I have used ether for starting things before. We used to use it to find vacuum leaks until I lost a little hair one day, now I use propane and watch the O2 sensor.



Thanks again from everyone. It was a long weekend and my fingers are a little sore and my house smells like diesel but all is good.



Jon T

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