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Old 09-12-2013, 10:10 PM
v8volvo v8volvo is offline
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Join Date: Jun 2009
Location: Montana, USA
Vehicle: '86 745, '83 764
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Yes, the car does have the standard gasser low-psi lift pump in the tank. Should have no trouble moving diesel or bio, maybe thick or half-frozen WVO wouldn't be good, but unless diesel or bio are semi-gelled due to low temps, their viscosity is not practically much different than gasoline's -- plus they lubricate where gasoline doesn't, probably a plus. The original LH-Jetronic EFI system in that car had two fuel pumps, a low-press one in the tank and a high-pressure pump under the floor. I eliminated the second but kept the first, since a booster is a benefit for the VE pump and also makes changing filters, priming if run dry, etc much easier. It runs whenever the key is on. I toyed with the idea of making some kind of system by which the pump would run off two relays -- one that automatically ran it for 30sec whenever the key was first turned to "run" for priming and then a second that would be triggered by the oil pressure switch opening so that it would continue to run whenever the engine was running, but would stop if the engine quit or if the driver only turned the key on to run the radio, etc. Would have been slick but more complex. GM 6.5TD has a similar system, which is known for issues. I ended up concluding simpler is better...

Interesting that hose failed, it was the original gasoline fuel hose. I wondered if it would be okay when I first put that together, -- I decided to experiment with the expectation that it would probably have a problem, but I put a lot of miles and time on it and it never showed any sign of suffering from diesel and bio when I had it, so I ended up figuring it would be fine. Guess it just took more time before it quit! Sorry you had to deal with it letting go, but sounds like your replacement worked. The unions in the line there are to adapt from the large 1/2" supply hose (previously to the gasoline fuel filter inlet and high-pressure pump) to the smaller 5/16" hose that runs up to the diesel fuel filter head on the engine. The 5/16 hose is a nylon-lined marine-grade multi-fuel product rated for use with diesel, bio, or whatever, so that should be fine. A new length to replace that stretch of big 1/2" hose should be all that it needs.
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