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Discussion Starter · #1 ·
Hi, so I'm in the process of getting my recently acquired 1971 1800E reliably roadworthy. After seeing how rusty the old gas tank was I decided to just get a new reproduction tank. After contacting several people (VP autoparts, Classic Volvo Restorations etc), it seems like nobody has the tank elbow barb fitting in stock and they aren't expecting them soon. I have this tank https://classicvolvorestoration.com/volvo-1800-fuel-exhaust-system-parts-/20318-fuel-tank-volvo-1800-ees-1970-73.html . Does anyone know the size of the elbow threads that go into the tank and the output size of the barb fitting? It looks like at least 1/2 inch NPT threads, but I can't tell for sure and would I be looking for a 5/16 barb or 3/8? I'm trying to find something on Summit or something that I can substitute so I can get my car back on the road. Thanks!
 

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Ok. I actually just went through this a few weeks ago.
I was told from the source that I bought my tank - that it was 3/8 NPT (National Pipe Thread).
I took my old one to the auto store (which is what I recommend you do) - and check the threads. Mine was pretty old and 'buggered up' but it was 3/8 20 (I think) or possibly 3/8-18 threads.

If you are ok with a barbed fitting (looks like you are) then they will have it at the local parts store. I had to look at a few to find the one with the largest hole through the middle to keep from impeding flow.

I found that these were not listed as 3/8" on the boxes in the store, they were listed as 1/4" because they were for 1/4" line.

If you have time, I would order one online similar to this:
Skandix helps to identify
http://www.skandix.de/en/installati...tank-Fuel-pipe-Fuel-pump-Carburettor/2000445/
then
http://www.skandix.de/en/spare-part.../1022871/?bi=bd0120e28103ca0e249ee6e2569868f2
or
http://www.skandix.de/en/spare-part.../1047823/?bi=bd0120e28103ca0e249ee6e2569868f2
 

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Discussion Starter · #3 ·
Thanks, I can't even get my old elbow fitting out of my tank so I had to wait for the new tank to see the plug size. The 3/8 npt thread size seems about right by my measurements with a micrometer. I wouldn't want to go down to 1/4 outlet size, though. I think the original outlet barb was 8mm or about 5/16 so I wouldn't want to restrict flow by going down to 1/4. I'm going to try to get 3/8 to 5/16 90 degree fitting and run 5/16 line from the tank to the filter. My original 3 port fuel pump has a larger suction fitting, though, so I don't think I can run 5/16 from filter to the pump. For whatever reason it seems that I need to run at least 3/8 from the filter to the pump, which seems like an odd design, considering everything else looks like 5/16.
 

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Thanks, I can't even get my old elbow fitting out of my tank so I had to wait for the new tank to see the plug size. The 3/8 npt thread size seems about right by my measurements with a micrometer. I wouldn't want to go down to 1/4 outlet size, though. I think the original outlet barb was 8mm or about 5/16 so I wouldn't want to restrict flow by going down to 1/4. I'm going to try to get 3/8 to 5/16 90 degree fitting and run 5/16 line from the tank to the filter. My original 3 port fuel pump has a larger suction fitting, though, so I don't think I can run 5/16 from filter to the pump. For whatever reason it seems that I need to run at least 3/8 from the filter to the pump, which seems like an odd design, considering everything else looks like 5/16.
The pump on my 142E was the same as on your P1800E (it died and I replaced it with one from a Nissan 280 Z which is a dead ringer for the later 2 port version).

Which fitting are you talking about? On the 1971 140E there is a elbow at the tank on the suction line. Its an odd arrangement, one arm of the elbow is threaded to go in the fuel tank fitting and the other arm is threaded to accept a tube fitting adapter which accepts about a 300mm length of metal tube with no barb which has an OD of about 7/16 - 1/2 ". The suction hose from the fuel pump is I think nominal 12mm ID. I can't remember whether I used 7/16 or 1/2" hose on the suction line; but, it was a tight fit over that tube attached to the tank. If the elbow you are talking about is on the pump suction line then it should have a 7/16" or 1/2" barb depending on which hose size you elect to use. Unfortunately I can't remember the pipe fitting size for the elbow

The discharge fuel line on the pump is definitely 5/16" (actually 8 mm). On the 1971 with the 3 port pump, the pressure relief line from the pump is 5/16". The fuel return line from the fuel pressure regulator is also 5/16". On the 140E, both the fuel return line and the overflow line connect to a shared Tee fitting on the gas tank. In 1972 or 1973 Bosch dropped the external pressure relief line from the pump (2 port version) and the Tee fitting changed to a simple elbow fitting to accept the return line from the FPR. The 140 requires Tee / elbow fittings because of the close proximity of the rear muffler. This might not be an issue on the 1800 so they might get away with straight fittings.

You make this statement

" and run 5/16 line from the tank to the filter ....... My original 3 port fuel pump has a larger suction fitting, though, so I don't think I can run 5/16 from filter to the pump."

The fuel filter must be on the discharge side of the pump, not on the suction side. Your wording kind of implies that it is not. The correct hose size would be 5/16 from the pump discharge to the filter and 5/16" from the filter to the fuel rail on the engine.
 

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Discussion Starter · #5 ·
I want to make sure I get this right. When I got the car the filter was between the tank and the pump and the documentation seems to say that this is correct http://new.volvocars.com/ownersdocs/1971/1971%201800/711800_02.htm. The original line that came out of my tank really looks like it's designed for 8mm, exactly the same as the filter inputs and outputs. The only barb/nipple that is larger than 8mm seems to be the suction port of the pump. I'm going to have to get my micrometer out to be sure.
 

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Discussion Starter · #6 ·
I just measured and outer diameter of suction tube from tank is 3/8, filter in and out are 5/16 and suction port on pump is 3/8. What I can't figure out is, if the diagram is right and the filter does go between the suction tube on the tank and the pump why does it go down to 5/16?
 

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Discussion Starter · #7 ·

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Well make me a liar. I thought that in 1971 Volvo switched the P1800E to the later style D jet plumbing arrangement which was used on the 142E. Does your car have the in-tank pre filter sock or did that not come until later? If you have the early type arrangement then you should have the mungo expensive fuel filter?

http://irollmot.ipower.com/oscom/product_info.php?cPath=26_32&products_id=292

If that is the case, then you are correct that the filter is on the suction side. It also appears that the pump changed slightly between the earliest and later 3 port design before Bosch ditched the 3 port completely. On the early, early design the pump outlet is on the head of the pump and on the later design the discharge moved to the back end of the pump body with the original discharge port being blocked off. If you have the early, early pump then my comments about the port diameters on the pump are probably incorrect.

As to your quandary about the fuel filter fitting size, did you get the correct 1970 1800E filter. If not, that might resolve your 5/16" - 3/8" problem.

If you go here:

http://volvo1800pictures.com/sweden/Volvo_1800_dokumentation_main_page_en.php

you can find the provisional service manual for the P1800E.

As to your new fuel tank, since it fits the 1970 - 1973 models does it have the plug in the bottom of the tank for access to a filter sock? If so, then the rest of the fittings may be set up for the later fuel system versus the early fuel system arrangement. You might need to look at the parts diagram for later cars to get the correct fittings for the tank.

Also something to consider. If your pump dies on you finding an exact replacement will be impossible or difficult and expensive. If you fit a later style pump or a modern pump you should plan to move the filter to the discharge side of the pump. The filter can restrict flow after it gets old and pumps really hate working against a negative suction head.
 

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Discussion Starter · #9 ·
I appreciate your knowledge and help on this. My original tank did not have the in-tank filter, but the replacement does. It looks like my car and others I've seen went with a cheaper replacement with 5/16 barbs. This is going to be a driver so dependability rules over originality. What if I ran 3/8 line from the tank straight to a new pump like the bosch 044 and put a filter on the discharge line from the pump. In that case would the fuel return line just go straight to the tank?
 

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I have no experience with the Bosch 044 pump. A major consideration would be the inlet and outlet port sizes. The 044 has a check valve on the discharge and looks like it is set up for a banjo fitting. It might be a slight challenge to find the correct metric fitting to convert the banjo to a barbed fitting. That actually might be a good thing because I expect you will want a 5/16 barb on the outlet to match up with the filter and the rest of the fuel line to the engine. You could then get a 3/8 barb for the suction connection to the fuel tank. The pump design is in-line as opposed to having all the connections on the head of the pump so you will have a little re plumbing to do.

If you are talking about the return line from the fuel pressure regulator then yes, straight into the tank and eliminate or plug off the overflow line from the pump that you are no longer using.

Check on the pre filter. Your new tank might have the bung to access the pre filter sock; but, there may not be a sock present. The socks are kind of stupid expensive for what they are so it would not surprise me if it did not come with a sock to keep the price down.

The original P1800 E suction side filter was plastic which was OK because it was low pressure. Do not use a plastic filter on the pump discharge because of the pressure. You can make those generic metal fuel filters work; but, they do cause pressure drop once they start to get the least bit dirty. The correct fuel filter (as per the later cars) is metal, about 75 -100 mm in diameter and about 75mm long (based on my memory from the last time I was under the car in that area). Like this thing which is what I have on my 1971 (the listing says 72 for the 1800)
http://irollmot.ipower.com/oscom/product_info.php?cPath=26_32&products_id=297

They have 5/16" barbed fittings on both ends. Might be a challenge to figure out how you are going to fit that if the space is tight. If you are not hung up about being original you could relocate the filter to the engine compartment which would make future filter changes much easier.
 
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