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.

Moderators: plenzen, Nissan_Ranger

User avatar
philip
Posts: 1494
Joined: 14 years ago
Location: Southern California, USA

#31

Post by philip » 13 years ago

TooManyIdeas wrote:Ok so the fuel only goes through the lift pump "screened". (Thanks for the English lesson Philip :wink: ) But I've seen finer wire mesh in screen doors.
EARLY on .... Al described Primary & Secondary filters at some detail. Do read.
TooManyIdeas wrote:Wouldn't this damage the lift pump at the very least?
For all those decade lift pumps having screen filters ... do you see lift pumps failing often?? (excluding deliberately self home mucked biodiesel or very old silt). Lets talk about why you are determed to suck up junked fuel in the first place.
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

User avatar
TooManyIdeas
Posts: 120
Joined: 14 years ago
Location: Albuquerque NM -VEGAS BOUND

#32

Post by TooManyIdeas » 13 years ago

:P your slipping a little Philip, that link was to a UPS battery post.

It's not that I'm determined to suck up junked fuel (but wait I thought the pump didn't suck lol) But I really need to send you a picture of the HUGH amounts of crud sitting at the bottom of the screen. It may block really large contaminants but the small ones (like freaking Volks Wagons) still make it though to cause damage. I simply want to minimize my risks. You talk about not needing better filtration but didn't you replace your lift pump and have your injectors rebuilt. :wink:

Remember I want to build an endurance truck. That almost requires ludicrous amounts of filtration.
82 Datsun 720 King Cab Diesel - FOR SALE !!!!
85 Chevy Monte Carlo CL
90 Toyota Pickup -SOLD
05 Kia Spectra 5
02 Dodge Dakota Quadcab
-OOOOOOOOHHHHHHHHH YEAH!!!!!

davehoos
Posts: 525
Joined: 14 years ago
Location: Karuah Valley,NSW Australia
Contact:

#33

Post by davehoos » 13 years ago

all of my nissan have had VE pumps,so the lift pump is after the filter.

most of our farms tractors and our isuzu rodeo and mazda T4100 have small screen in the banjo bolt before the pump.this thimble size filter blocks up with small amounts of paint,rubber,and the goey substance that forms in fuel drums.completly usless.putting afinner filter on the suction side can result in fuel starvation.

i think the mazda has an OFV and an old canadian ford tractor engine[one stationary] has it.the rodeo hasnt it has a restriction on the return pipe.ive not seen these on SD33 patrols but im thinking in hindsite that several vehicles that had after market fuel filters fitted suffered from bleeding and starvation problems should have had one..the end fix was to fit electric pump at the fuel tank[some had twin tanks]..i thought the ofv was more to do with cold weather operation.lat model nissans have temperature compensation that shuts of the return line.the isuzu has an electric solinoid on the tank return.
WCJR31 Skyline.3.0 manual.wagon
R31 SKYLINE/Passage GT/PINTARA
LPG Ford Falcon 99-06 93 Disco
Local Shire Southern Zone Mechanic.

User avatar
philip
Posts: 1494
Joined: 14 years ago
Location: Southern California, USA

#34

Post by philip » 13 years ago

TooManyIdeas wrote:SNIP- You talk about not needing better filtration but didn't you replace your lift pump and have your injectors rebuilt. :wink:
Using your theory ... ALL parts you replace while you own the truck are entirely due to your failing (including those originally when the car was brand new). :wink:

Do you know the replacement recommendion of the injection nozzels? :wink:
How long are lift pumps are supposed to last? :wink:
Do you know how many miles are recommended replacing the "screen" and "secondard" filters? :wink:
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

User avatar
asavage
Site Admin
Posts: 5349
Joined: 15 years ago
Location: Duvall, Wash.
Contact:

#35

Post by asavage » 13 years ago

davehoos wrote:the end fix was to fit electric pump at the fuel tank[some had twin tanks]
I am firmly against electric fuel pumps. They are far, far less reliable than mechanical pumps. And if one is worried about unfiltered fuel in a pump, the same applies for an electric pump.

The Inline IP's lift pump works very well as is. Don't pour mud in your tank. The lift pump can handle small crud, it's proven it over millions of miles (in MB as well as Nissans). Don't fix what isn't broke -- unless you really want to (see my posts on lube oil bypass filtration :) ).
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

davehoos
Posts: 525
Joined: 14 years ago
Location: Karuah Valley,NSW Australia
Contact:

#36

Post by davehoos » 13 years ago

the pump in common use here looks like a transformer.it operates a shuttle inside a tube.these will pass the proverbial gravel.they rattle a little on startup.the rotary pump is not suited unles the fuel it cleanbut they have difficulty lifting fuel,i had a tiawanese SU type diaphram pump on my 910.i payed a little amount for it but they soon became expensive.the vavle easily passed items the size of fuel lines.a mate of mine has a 60's rover 3 liter i think the pump is used on a JAG,its a SU with double diapram,it still uses the old points setup.

i have struck some rattler pumps with a non return flap valve screwed into suction side end.this valve is easily fowled.iv seen filters added here as part of the deal that need regular servicing.

25-30 years ago when i started work,average age of vehicles was 25-30 yrs+.unfortunatly parts if available was uneconomical.now if it brakes down you trade it in.

the lift pump valves are the parts i commonly replace most are not available seporatly.ive had to make them in some cases.also the primer pump.its often cheeper to blank of the lift pump and fit an electric pump.this also fixes the need for owners to get out and bleed/flush fuel when used in cold weather.diesel repair shops have been dificult to deal with in the past,lately they are closing up and retiring as it cheeper to buy directly replacement part assembleys and large number of non servicable modern diesels.

P/S
on the army landrovers we used air brake hose for fuel lines,heat in water shove over 5/16 steel pipe with a little locktite[superglue].heat to shape into possition.is this pipe safe for BIO diesel?? etc.ive used offcuts on many conversion to tidy the under bonnet area..
WCJR31 Skyline.3.0 manual.wagon
R31 SKYLINE/Passage GT/PINTARA
LPG Ford Falcon 99-06 93 Disco
Local Shire Southern Zone Mechanic.

User avatar
TooManyIdeas
Posts: 120
Joined: 14 years ago
Location: Albuquerque NM -VEGAS BOUND

#37

Post by TooManyIdeas » 13 years ago

I appreciate all you guys’ input, but I’d still like to know how to move the OFV from off the secondary filter. Where I live, I don’t exactly have the option to “not put mud in my tank.” I’ve been to several different stations and I have not seen any improvement in the quality of their fuel. Therefore my only option is to adapt. I understand you wouldn’t do this but, if you were, how would you go about doing it?
82 Datsun 720 King Cab Diesel - FOR SALE !!!!
85 Chevy Monte Carlo CL
90 Toyota Pickup -SOLD
05 Kia Spectra 5
02 Dodge Dakota Quadcab
-OOOOOOOOHHHHHHHHH YEAH!!!!!

User avatar
asavage
Site Admin
Posts: 5349
Joined: 15 years ago
Location: Duvall, Wash.
Contact:

#38

Post by asavage » 13 years ago

The OEM filter is completely adequate for reasonable fuel. The OFV only bleeds fuel back to the tank.

If you are changing to a secondary fuel filter that does not have a place to bolt the OFV, you could make your own adapter block tee for the "out" line of the new filter, screw the OFV into it, done. When the lift pump pressurizes the new filter to 16-21 PSI, it'll bleed pressure to the return-to-tank line, just like stock.

Or you can do what Philip did, and screw a different pressure regulator (for that is what it is) into one of the IP bleed screw holes.
philip wrote:This modification requires an aftermarket (adjustable) pressure relief control bolt (smaller thread size too) and a smaller double outlet banjo fitting.
Image
TooManyIdeas wrote:does anyone have a price and part # for the over flow valve?
If you mean the one Philip used, rather than the OEM one, Philip said that he doesn't have any info and to contact Edgar:
philip wrote:My diesel man (Edgar) at DSI evaded that very question. Since the pressure control bolt and banjo were new pieces, both must be from something Bosch uses currently.
Image
Edgar Sibiglia
350 E. Orangethorpe Ave #12
Placentia, CA 92870
714.528.8442
714.528.8464 fax
Last edited by asavage 12 years ago, edited 1 time in total.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

User avatar
philip
Posts: 1494
Joined: 14 years ago
Location: Southern California, USA

#39

Post by philip » 13 years ago

asavage wrote:SNIP- The OEM filter is completely adequate for reasonable fuel. The OFV only bleeds fuel back to the tank. -SNIP-
Remind that the "OFV" has a 0.015" orifice which means Lift Pump pressure is not limited to the OFV's 20 psi top-off. It is the piston's spring compression that determines the real total line fuel pressure. THIS discovered high pressure is why I used the adjustable pressure relief back down to 20 psi. My APR open is about 1/8" dia.
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

User avatar
asavage
Site Admin
Posts: 5349
Joined: 15 years ago
Location: Duvall, Wash.
Contact:

#40

Post by asavage » 13 years ago

philip wrote:Remind that the "OFV" has a 0.015" orifice which means Lift Pump pressure is not limited to the OFV's 20 psi top-off.
Allow me to doubt this, until it can be verified by a completely different truck/installation. Unless the volume on the lift pump is higher than I think it is, .020" will flow a lot of fuel.

I want to hear of someone else getting the same results on a pressure test as you did, or I want to perform the same test myself on my '81 720 or whatever. Until then, I will have to say, "maybe". Those Japanese, they are clever folk.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

User avatar
philip
Posts: 1494
Joined: 14 years ago
Location: Southern California, USA

#41

Post by philip » 13 years ago

asavage wrote:Allow me to doubt this, until it can be verified by ... (snip) ... or I want to perform the same test myself on my '81 720 ....
But of course! I've been a cutting edge before. LOL

Lift Pump note Do note that the spring behind the plunger piston (Lift Pump) has to be capable greater than the OFV's 20 psi for it to overflow. :wink:
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

pbknowles
Posts: 95
Joined: 14 years ago
Location: Illinois, USA

#42

Post by pbknowles » 13 years ago

I will verify Philip's pressure measurements with the stock OFV. After cleaning mine and verifying it moved OK with a wire, and even pulling off the line going back to the tank and directing it to a bucket (to eliminate possible restriction) mine would still peg a 30 psi gauge when revved up in neutral. So I tried taping the gauge to the windshield and going down the road with the same result.
SD22 powered '85 Chevy S-10

User avatar
asavage
Site Admin
Posts: 5349
Joined: 15 years ago
Location: Duvall, Wash.
Contact:

#43

Post by asavage » 13 years ago

Thanks, Phil.

So, now we need a secure, repeatable source for the upgrade OFV.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

User avatar
philip
Posts: 1494
Joined: 14 years ago
Location: Southern California, USA

#44

Post by philip » 13 years ago

asavage wrote:Thanks, Phil.

So, now we need a secure, repeatable source for the upgrade OFV.
You want my V2 "ofv"? I do have photos. :wink:

But notice the 1981 Datsun Product BulletinLift Pump operationwe've had over than a year (Apr 27, 2006). :wink: Even this is only their "idea" .... 'cuz parts actual sold are different. Just one example ... look at Galen's injection pump. His' lift pump is reverse ... that were never mention.
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

User avatar
asavage
Site Admin
Posts: 5349
Joined: 15 years ago
Location: Duvall, Wash.
Contact:

#45

Post by asavage » 13 years ago

philip wrote:You want my V2 "ofv"? I do have photos. :wink:
Yes, we want photos of v2.0 . When can we see them? ;)
But notice the 1981 Nissan Lift Pump operation we've had over a year (Apr 27, 2006). :wink:
I thought that was a 1982?
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest