Pressure Regulator O Rings

[Brisfx]

Ok

I was having hot start issues so I pulled the pressure regulator out of the F/D and sure enough the O ring on the tip was broken. So I replaced it, ran perfect for a day then hot start problems again.. Spoke with Dave at DMC Midwest (Thanks buddy) and he suggested one of the banjo bolts comming in at right angles to the regulator may be an issue. Sure enough pulled it out and its broken again. So doubled up on the copper washers on the back banjo bolt and today problems again. Pulled the regulator and the larger rear O ring is toast and the small front one has a piece missing. I am ready to blow the damm thing to pieces.

Ant suggestions?????

[Bitsyncmaster]

I found a smaller viton O-ring from Master Carr but will have to look if I wrote the part number down. Wish the old forum data was back. Maybe someone else has the number.

[content22207]

Welcome to the brave new world of gasohol -- ethanol absolutely tears up rubber components that are formulated for gasoline exposure only.

Yesterday I had to convert one of my church's school buses to an electric rotary vane fuel pump because gasohol caused the diaphragm in its mechanical fuel pump to split -- in less than 3 years time!

Here's a good question: there are O rings on the barrel that meters the fuel to the 6 injector chambers. Will ethanol tear them up as well? The only way to remove that barrel is to take the fuel distributor apart.

How about the rubber seal on the accumulator piston -- will ethanol cause it to fail prematurely?

IMHO: The sooner our government gets out of the fuel additive business, the better.

Bill Robertson
#5939

[Bitsyncmaster]

Welcome to the brave new world of gasohol -- ethanol absolutely tears up rubber components that are formulated for gasoline exposure only.

Yesterday I had to convert one of my church's school buses to an electric rotary vane fuel pump because gasohol caused the diaphragm in its mechanical fuel pump to split -- in less than 3 years time!

Here's a good question: there are O rings on the barrel that meters the fuel to the 6 injector chambers. Will ethanol tear them up as well? The only way to remove that barrel is to take the fuel distributor apart.

How about the rubber seal on the accumulator piston -- will ethanol cause it to fail prematurely?

IMHO: The sooner our government gets out of the fuel additive business, the better.

Bill Robertson
#5939

So far the static seals seem to hold. It's the dynamic (always moving) O-ring that is showing problems.

Do you have ethanol gas in Australia?

[Bitsyncmaster]

Did not save the part number but the bag is labeled:

75 VITON
SIZE - 1.9 X 3.8
QTY - 25

[82DMC12]

I see there are two gas stations in my area that sell non-ethanol gas. I think I am going to start filling up there with the D. This is ridiculous.

Andy

[DMCMW Dave]

I've been running nothing but ethanal gas in my D since 1997 (living in the corn state I don't have any choice in the matter) and have NEVER seen an issue that I could attribute to it. I think the problem is overblown. I never touched the fuel distributor until last year when I powdercoated the intake.

PS the Original Poster is in Australia. They have some pretty onerous car laws but I don't think this is one of them.

[content22207]

I've lost two mechanical fuel pump diaphragms this year, one of which was less than 3 years old and only had 2,400 miles on it -- you Midwesterners can keep your stupid corn gas.

Bill Robertson
#5939

[Chris4099]

Considering the failures are just days apart, I think it's pretty ridiculous to even think of blaming ethanol. Sounds like either the O-rings were damaged when being installed or just plain defective. To the OP, how were you installing them?

[Brisfx]

The small o ring was replaced. I dont think its anything to do with ethanol. As i mentioned it looks like its impacting on one of the banjo bolts that comes in at rightangles. Still to replace te rear one

Brad

[David T]

It seems that once the PPR is disassembled people have issues with cut "O" rings. That raises several questions.
Are the "O" rings that are being used as replacements the correct size and materiel?
Are they being assembled properly?
Are the "O" rings getting cut during reassembly or disassembly?
My advice would be if you have not messed with your PPR you should not take it apart. They only seem to have problems once they have been "touched". I agree "O" rings used only for static sealing purposes seem immune to damage. Not counting the "O" rings on the water distribution pipe under the intake manifold. As much as I would also like to blame Ethanol for all of the ills in the fuel system it is hard to do that when you remember many of the parts are over 30 years old.
David Teitelbaum

[Bitsyncmaster]

I found the part numbers for the o-rings I ordered. I ended up using and recommending the smaller one. The Buna ones I ordered to do swell testing soaking in E-10 gas. The Buna did expand quite a bit and the Viton did expand at all.

Products
Line Quantity Part Number Description Unit Price Total Price Ships
1 1
Pack 9263K163
Metric Viton O-Ring 2 mm Width, 4 mm ID, Packs of 25 (Same as 9263K11) $6.44 $6.44 today
2 1
Pack 9263K637
Metric Viton O-Ring 1.9 mm Width, 3.8 mm ID, Packs of 25 (Same as 9263K11) $12.79 $12.79 today
3 1
Pack 9262K163
Metric Buna-N O-Ring 2 mm Width, 4 mm ID, Packs of 100 (Same as 9262K41) $4.30 $4.30 today
Merchandise $23.53

[jmrydholm]

I too have a ridiculously irritating hot-start problem, but I believe I've already had the O-rings done on my car. The pump and accumulator are also new, but I had a fuel tank overhaul recently as bad gas was in there for a year or so. I noticed when I start the engine cold in the morning, it fires right up, but after driving it most of today, it's a pain in the backside to start. I also hear a "thunk, thunk, thunk" sound coming from the accumulator area right under the car. I laid down and stuck my head under there to make sure that's where I heard right. Could the bad gas have spoiled my accumulator? I have one of John Hervey's.

[Chris4099]

That sound is your accumulator rapidly decompressing from loosing rest pressure so fast. So time to look at that O-ring if you aren't sure about it. You can test your accumulator too, but it's probably not the issue if it's so new.

[Bitsyncmaster]

Yes the thump sound is the accumulator. My car will also do that. But you should not here it very often. The faster the thumps the faster you are loosing rest pressure. I've been running John's accumulator for 5 years now and so far so good.

[jmrydholm]

It's about one "thump" a second.

[Bitsyncmaster]

It's about one "thump" a second.

You have a massive rest pressure leak.

Have not timed mine but I think its 15 30 minutes for one thump.

[jmrydholm]

I just contacted John Hervey and ordered the O-rings about an hour ago, I'll see what he suggests! Hopefully I won't need another accumulator...

[Chris4099]

I've had good luck with John's PPR O-rings. When my original one finally failed (deformed over the years), I used his and it worked great. I then later replaced it thinking they failed (turned out to be an NOS replacement accumulator) and put in another vendors. That one ended up chipping a few months later and I installed another set from John again. That's been going strong for several years now.