I switched to veg tank. Surging like air in system, won't get up to highway speed. Sure enough inline filter is only half full. TIghten hose clamps. Pump the primer like crazy. Loosen outgoing banjo bolt and pump like crazy.

Car will start and run fine, but if I accelerate too fast or go above 55 it will hold that speed and then start slowing down.

The threads I've read about dealing with the air in the lines all had 'won't start' as part of the symptoms. It seems to me that the air should be pushed back to the tank while it's running and all will be fine. no?

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1981 300D 205,000 mi.

I went out and pumped the (new style) primer 151 times, then cracked the injector lines and turned the engine over a few more times. Drove it to work, filter still half full.

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1981 300D 205,000 mi.

Main fuel filter partially clogged? Tank filter?

The clear primary filter is always going to have a big bubble inside, its normal.

Get it warm on Diesel then pull over and watch what goes on in the filter when you switch over to veg. If you see bubbles flowing through the filter then you know you have an air leak along the way.

Also make sure the VO is at least 160*f before switching.

The fault you describe is exactly like fuel starvation/restriction.......

Make sure the fuel supply lines are wide enough for the thicker veggy oil....

6mm ID line is a little narrow for veggy, Better to go up to 8mmID or better still, 10mm........

Check the in-tank strainer, (If you're using original fuel tank for the veggy) or any other possible restriction in flow. Veggy being much thicker than diesel, it really NEEDS no restrictions at all from change-over valves, filters, or other plumbing).....

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http://i190.photobucket.com/albums/z...0TDnoplate.jpg

Alastair AKA H.C.II South Wales, U.K. based member

W123, 1985 300TD Wagon, 256K,
-Most recent M.B. purchase, Cost-a-plenty, Gulps BioDiesel extravagantly, and I love it like an old dog.

W114, 1975 280E Custard Yellow,
-Great above decks needs chassis welding--Really will do it this year....

I did have to change out a clogged inline filter. Perhaps it gunked up someplace else as well? I'll check the main supply valve first, since it doesn't go away when I switch to diesel, I would assume it's clogged in the supply line/supply valve. If it was between the tank and the valve, it would go away when I switch tanks.

I didn't know that a clog would introduce air into the system. This isn't just a bubble, the thing is half empty.

I'll pull off the supply line and check the valve.

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1981 300D 205,000 mi.