serious engine problems when running on WVO

[v8volvo]

I just finished up installing a greasecar kit in my Rabbit, and am having some problems that I thought this forum might be able to help me with.

It seems like when running on veggie, the engine is getting very bad fuel injected. It clacks loudly, bucks, smokes, and generally acts very unhappy. I'm almost certain the fuel is more than warm enough--the fuel tank is extremely hot, the filter head is very hot, the HIH lines are extremely hot, etc. I checked all the hose clamps and there are no air leaks. I'm not experiencing any oil burning, compression loss, coolant use, power loss, or excessive temperature, and got 42 mpg climbing the Rockies with the car loaded to the gills at 60-70 mph.

I'm in the middle of a cross-country drive from Seattle to Boston, and had been hoping to do it on veggie. The first day was done on all veggie, and it was running pretty bad on veg but would smooth out when I switched back to biodiesel or diesel. Stupidly, I did a second full day on veggie, and now even on diesel it is running bad. It takes a little more time to start it when warm, it blows black smoke on startup, and it makes nasty noises and bucks. Finally I pulled the injectors out today to see what was going on. I had them rebuilt 3000 miles ago, and the nozzles still look good, no cratering or erosion, a little carbon but nothing abnormal. Same goes for the heatshields and prechambers, nothing too out of the ordinary. I did notice some dark, semi-sticky coating, maybe varnish, on the body of the #2 injector only. It was not on the face, but on the body between the nozzle end and the threads where it screws into the head.

I thought I knew these engines pretty well, but I'm stumped. I'm going to get new heatshields, reinstall the injectors, and maybe run some diesel purge...anyone have any other ideas, or anything else I can check?

[lyeinyoureye]

Have you tried fiddling with injector breaking pressure? Even with the WVO at a good temperature pre-injection pump, and the injector increasing temp/decreasing viscosity more, the viscosity may still be too high for proper atomization.

[v8volvo]

I have not, but I know they are all closely within spec (recently rebuilt). One thing I was wondering--does veggie have a higher cetane than diesel or biodiesel? Is it customary to retard pump timing when running on veggie? I do have my pump set a little ahead, at .96, so maybe what I'm hearing/feeling is just premature ignition. Does anyone know how veggie affects actual timing?

[Fatmobile]

Without any clear fuel lines on the vegy setup, it's hard to tell for sure if air is getting into the fuel.
Do you have a vacuum gauge?
I usually run advanced because I think vegy burns slower... lower cetane. It has always worked better for me.
Did the injection pump timing jump a tooth? I've heard of this happening to people. That would effect how it runs on both diesel and vegy.
Another thought; if there was air coming in with the vegy fuel, it would mess with the fuel's lubricity and could have caused extra wear on the pump.
Black smoke on startup now? Normally a little white right? Air filter clogged?
Where are you at now?
How was your vegy fuel processed? What micron? Any veg in the diesel tank?

[v8volvo]

Vegy is fresh soybean oil from Costco. Totally clean. Water separator has no water in it. Air and all fuel filters are brand new.

It's now back almost to normal on diesel...still loses revs kinda slowly between shifts, which probably means injectors, but basically running good on diesel. I tightened up some loose pipe connections on the veg filter head, which might fix it--I'm about to hit the road and try it.

I'm leaving Denver, CO in a few minutes and will cross Nebraska today. I will be in Iowa tomorrow, going along I-80...Fatmobile are you anywhere near there? If you happen to have a moment and are nearby it would be awesome to have you take a look at and see what you think...only if it's convenient for you though, of course.

Thanks!

[Fatmobile]

Only things I can think of that would cause the RPMs to drop slowly are, like you said, bad injectors spraying improperly, sometimes the springs on top of the injection pump bind and need to be sprayed with cleaner/lube and sometimes the max fuel screw is turned in too far and the extra fuel takes time to burn.
I'm about 2 hours north of I-80. A guy brought his Rabbit down from MPLS for me to help him work on. The body was so bad back by the rear beam that I told him I wouldn't do anything but engine work until he welded it up. He's going to be welding on it tomorrow morning and I'm not sure what he has planned for the rest of my day. He trailored it all the way down here, planned it ahead of time ... so I can't really take off on him and head down there.
I'll PM you my phone number. If you want to drive all the way up here, I'll take a look at it for you. Maybe we can put a vacuum gauge on it, to rule out fuel line obstructions. Maybe some clear fuel line on a stretch of return line so we can see if there is air in the vegy lines.

[v8volvo]

Hi guys, sorry I never followed up on this thread. I made it to my destination successfully on biodiesel (and diesel where necessary ), but immediately became very busy and forgot about this.

I've decided that the engine runs fine on biodiesel and diesel now; whatever was happening before has either cleared itself up, or I was hallucinating (don't think so). It does seem like the mileage is pretty bad (I need to measure it properly, to know for sure), but I think it's running fine.

I have done some more detective work on the SVO system, and have decided that it must be an air leak problem. Here's what happens, now that I've had time to see fully what's going on. After I switch to veggie, it runs beautifully on SVO for a while. If I keep the revs low and am easy on the throttle, this nice period can last as long as 5-7 minutes. If I merge onto the highway, or accelerate hard for another reason, or shift late and get the revs high, it starts to clack and buck and idle weird a little. If I do more high revs or heavy pedal, it gets worse and worse until it is painful to drive it. Then I switch back to diesel or bio, and as soon as all the veggie has cleared out of the metal fuel pipes it runs fine again.

I have a few ideas about why this might be happening. The Greasecar system runs looped when in veggie mode, so any air that gets in would not have any way of getting out. I guess that means that if, for instance, the IP was leaking at the shaft seal but not very much, it would not matter when running in non-looped mode, like what it does when on diesel or biodiesel. However, in veggie looped mode, enough air could accumulate in the lines over the course of several minutes to start causing problems. Of course if the revs or load got high, it would try to suck more fuel, and exacerbate the air leak. I'm still kind of at a loss as to how air in the fuel could cause the horrible clacking noises I have been getting, but one theory is that once the air gets into the metal fuel lines, it would compress each time the plunger tried to pump fuel to each injector, delaying the injection of fuel and therefore effectively retarding injection timing. Does that sound feasible? I'm in guess mode here, but I think this might be the right track.

What I was going to do was install clear line on both the supply and return sides of the pump. If there are bubbles from supply and return, I guess the leak must be somewhere before the pump. If there are only bubbles in the return, then the leak must be in the pump or in one of the injectors, right? Also, I might try routing the return veggie to a separate container, thereby breaking the loop and preventing air from getting trapped.

Any thoughts on all this? Thanks for all the help, I'm still learning here...

[Fatmobile]

I was at a festival this weekend and had a chance to work with some people with a Greasecar setup in a vanagon with a 1.9 turbo diesel.
They said they had to change their fuel filter every 500 miles.
A vaccum gauge on your fuel line will tell you so much about what is going on with the fuel system.
I also noticed Greasecar doesn't have any clear section of line that would allow you to observe the fuel in the lines. They have long sections that aren't covered in any HWH or anything and it would be great to be able to see through.

[v8volvo]

Every 500 miles?!?!? Hmmm...and that's on a 10 micron filter too, which is not even that fine. They must not be prefiltering very well. I'm using virgin crated soybean oil and have driven a total of about 70 miles on this filter, so I think it's basically impossible that it would be clogged. This is starting with a dry, clean fuel system too.

I am going to find some clear lines to put on next weekend, and maybe get a vacuum gauge on it at that point too.

I took my fuel inlet bolt to a machine shop to have it tapped to accept the stock engine temp sensor off my spare motor, and they were concerned that the material in the inlet banjo bolt would be so thin after tapping the threads into the top that it would break. Has this ever been a problem?

[seth]

What are you guys using for a vac. guage and where in the fuel system?

[surfcam]

I though Fatmobile mention a 1/8 pipe thread into the top of the inlet banjo. Or find a double connection banjo off a gasser.

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