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Discussion Starter #1 (Edited)
I'm rehabbing a recently acquired 322 and, among many other things, replacing all the fuel lines.
I already replaced the long fuel line between the pump and the tank with 1/4" ID fuel line, as I always use 1/4" fuel line and I have a good supply of it ready to go.

Then I started looking things up. (DUH)

My 322 Parts Catalog (PC2149) says the following:

Fuel line is 985mm = 39" long. It does not give the ID, but it does give the PN to use - M88203. From what I can find online, M88203 is 5/16".
Do I need 5/16" fuel line instead of the 1/4" that I already installed? (I can still correct my mistakes).
The swollen and soft line that I took out was 5/16" (that should have been my first clue, but I assumed it was wrong!).

The pick up hose in the tank is 102mm = 4" long. It does not give the ID, but it does give the PN to use - M63270. I cannot find the ID of that hose.
Does anyone know the ID of M63270? The OD also must fit thru the rubber grommet (M88976) to allow the fitting (M65796) and grommet to go back into the tank.

I'm off to NAPA shortly to pick up fuel line, but thought I'd ask what the correct sizes would be, as I can still make corrections.
And the next one who comes along with these same questions will be helped out as well.

Thanks in advance!

Update - It would seem to me that because the ID of the pickup hose must be thinner than the 1/4" fuel line, the 1/4" fuel line would not make a difference as the narrower pickup hose would determine max possible flow.

Update # 2- Just returned from NAPA. Bought some fuel pickup hose. The elbow fitting (M65796) is determining max flow, I believe. The OD at each end of the elbow fitting is 1/4". The ID at the top of the fitting is approx 1/8". The ID at the bottom of the fitting is approx 3/16". It would seem to me that the 5/16" fuel line serves no real purpose and that 1/4" fuel line is just fine.
 

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Ken, He-he, I was in the process of looking up the fuel line info and then I saw your "update." I agree with you that 1/4" should go from the pickup to the elbow, the elbow to the pump, the pump to the filter, and finally the filter to the carb...!/4" tubing for fuel line on a 322! Bob
 
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Discussion Starter #3 (Edited)
Bob - Thanks for the advice. I agree it all should be 1/4" ID. I just checked the pump to filter, and filter to carb, and it's also old soft & swollen 5/16". I'm going to replace that also with 1/4".
 

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Merc, I posted on GTT (to Drgibby) about the 332. 322 has a carb, maybe 1/32 main jet, 332 has 3 injectors, unsure if fuel requirement would be sufficient with 1/4". Bob
 

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Discussion Starter #6 (Edited)
Now that I've completed the 322 fuel line replacement I'll add a few closing comments for those who come along later.

I used 1/4" fuel line from the tank fitting all the way to the carb fitting. It works, but ....

The parts catalog says to use M88203, which is a 5/16" fuel line. That's what I actually found on my 1990 322, from the tank to the carb.

However, all the 322 fittings are not 5/16". The tank fitting is 1/4", the fuel pump is 5/16" but the 1/4" line fits on easily over the metal line on both sides. The plastic fuel filter is 5/16" and it takes some patience to get the 1/4" line on both sides of the filter without bending the plastic. The carb fitting is 5/16". So, the next time I do this on a 322, I'll use both 1/4" and 5/16" fuel line.
 
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Now that I've completed the 322 fuel line replacement I'll add a few closing comments for those who come along later.

I used 1/4" fuel line from the tank fitting all the way to the carb fitting. It works, but ....

The parts catalog says to use M88203, which is a 5/16" fuel line. That's what I actually found on my 1990 322, from the tank to the carb.

However, all the 322 fittings are not 5/16". The tank fitting is 1/4", the fuel pump is 5/16" but the 1/4" line fits on easily over the metal line on both sides. The plastic fuel filter is 5/16" and it takes some patience to get the 1/4" line on both sides of the filter without bending the plastic. The carb fitting is 5/16". So, the next time I do this on a 322, I'll use both 1/4" and 5/16" fuel line.
Old thread but if by chance someone is there, that was a good write up but I didn't see anything pro or con about using the 1/4 fuel line inside the tank. I'm presently replacing the grommets and I'm at the elbow fitting. Ac comment or two, as previously noted I'm unsure whether the regular 1/4 fuel line ( Gates, has the white stitching halfway around the hose inside ) is acceptable or not. The one I removed was also black, around a 1/4 inch diameter, but no markings.. Second my inside the tank hose is nowhere near 4 inches long. That said, my hose first fits in the brass nipple, then after the hose there is a another metal piece that has a nipple and attached to that is a strainer that apparently is all the way at the bottom of the tank. All told I suppose the length could be 4 inches but certainly not just the hose . Does yours have that second metal piece with the strainer attached ? Hope this is of interest to someone else.. BTW, mine is a 1992 322. The grommets/hose issues I guess are to be expected at 29 years old. I do wish JD found another way to run the gas/low sensor lines instead of the rubber grommets...
 

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sorry to butt in I'm also doing my fuel lines and hydro line on 318. my rear hydro tube and sight tube is totally gone. what size clear tube can I use back there and just run the clear tube through the bracket? its still 1/4 id correct? can I buy something small enough od to go through that bracket? thanks.
 

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found old thread on here about 1/4 line from autozone and just drilling out bracket to make fit. makes sense.
 

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found old thread on here about 1/4 line from autozone and just drilling out bracket to make fit. makes sense.
Mine is also missing the last foot or so. I still have the sight tube but it just hangs and droops down past the bracket. It's supposed to fit back in the hydro but I haven't gotten to it yet..
 

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sorry to butt in I'm also doing my fuel lines and hydro line on 318. my rear hydro tube and sight tube is totally gone. what size clear tube can I use back there and just run the clear tube through the bracket? its still 1/4 id correct? can I buy something small enough od to go through that bracket? thanks.
I would use the 1/4 tubing that they use in weed eaters/chainsaw as it is resistant to gas and oil and is semi-transparent.
 

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As far as fuel line 1/4 flows sufficient fuel for our small engines. The difference in 1/4 versus 5/16 would be the speed at which the fuel moves.Being pulled by vacuum the 5/16 would be better than 1/4.
 

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Discussion Starter #13 (Edited)
I've done a bunch of these fuel tank flushes and rear hydro lines lately on my 318s and 322s. I'll add details on what I've found that works well for me.
Purists may not approve, however, as I'm no longer factory correct.

For my 318s - I always first remove the tank and clean it out. The tank almost always contains a lot of debris, old broken off hose pieces, old pickups, etc.
I replace the fuel line from the steel tank elbow to the fuel pump with 1/4" ID standard black fuel hose. I bypass the on/off/reserve valve as I've never found it to be useful, and it only complicates the hose replacement process. I leave the on/off/reserve valve in place for a correct "look", but it serves no purpose on my 318s. I relocate the standard fuel filter along the firewall before the fuel pump. I put a new shutoff valve after the fuel pump and before the carb.
For the tank, I use a new fuel pickup (AM54051), the "reserve" hole elbow (M65796), new grommits / bushings (M149638), a 316 tank plug /rivet (16H1290), and 1/4" ID tygon fuel line in the tank. The 1/4" ID (yellowish) tygon has a smaller OD than the standard black fuel line, and therefore it passes nicely thru the new (red) grommit. I use about 4" of tygon attached to the elbow fitting, then push it thru the grommit, then attach the fuel pickup. I leave the grommit on the section of tygon and push that into the tank. Then I push the steel elbow into the tank. Some silicone lube helps it all slide in. I make sure I orient the tygon hose and pickup toward the lowest part of the tank, which is toward the center front. (That's the old "reserve" area). The other hole in the tank gets a new grommit, and then the 316 steel rivet gets pushed in. That seals that hole. (The 316 & 318 use the same tanks, with 2 fuel line holes, but the 316 does not have the on/off/reserve valve so the second hole is plugged with the rivet in 316 Onans).
For the hydro line on the rear, I use standard black 1/4" ID fuel line, along with the OE sight tube (M94719), all fastened with OE style spring clips. Many like to use clear 1/4" ID tubing found at the hardware store, but I have come across many clear tubes that have become very brittle due to the hydro fluid.

For my 322s, I do pretty much the same.

Hope this helps with some of the recently posted questions.

Edit - a pickup with a check valve may be a better choice. I think I'll use AM52039, instead of AM54051, in the future.
 
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