Over Fuel Valve (OFV) operation

SD diesels were widely available in the US in the 1981-86 Datsun/Nissan 720 pickups, and in Canada through '87 in the D21 pickup.

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Nissan_Ranger
Posts:266
Joined:13 years ago
Location:Canada

#61

Post by Nissan_Ranger » 12 years ago

I've been going with the stock set-up less the OFV valve and have not had a problem since I punched it out. YMMV

N_R
The old 'six gun' was as popular as the cell phone in its time and just as annoying when it went off in the Theater.

Tracteur Tom
Posts:11
Joined:12 years ago
Location:France

#62

Post by Tracteur Tom » 12 years ago

Thanks N R. The problem with that is you will not create a pressure in the IP fuel chamber as it is open to the return line without a restriction. Yes it will work and is the set up on many a diesel of old I've looked at. But, a little pressure in the IP fuel supply line (1-2 bar) is good for stability and air pocket release I'd have thought.

I think one of the reason's Philip modified his set-up was because he thought he had too high a pressure. It wasn't clear to me from the postings as to whether the problem was caused by a faulty OFV or the updated lift pump he had. I wonder if you could modify the OFV with a slightly larger orifice, this should bring the pressure down ?

Tracteur Tom
Posts:11
Joined:12 years ago
Location:France

#63

Post by Tracteur Tom » 12 years ago

I found this thread and though it would be good to reference it here:

http://nissandiesel.dyndns.org/viewtopic.php?t=1153

seems Philip did have an answer after all :D

Skeeter2u
Posts:6
Joined:8 years ago
Location:Yukon Terr.

Re: Over Fuel Valve (OFV) operation

#64

Post by Skeeter2u » 4 years ago

I think the air comes from the fuel discharge line, that goes back to the tank from the filter housing; it is the only line that is open to the atmosphere, as it dumps in the tank with no line into the fuel. I have connected the return line and the discharge line from the filter housing, and pluged the two ports on the filter housing. I have been able to drive with the tank below 1/8th, and previously it would quit if half or below. So far so good. I am now unable to reduce the fuel pressure form the delivery pump, but so far have not blown any hoses.

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