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Author Topic: '99 fuel filler gutting
Dirt Surfer Verified Driver Made Donation to Website
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On the two previous SMs I built I removed the restriction in the fuel filler throat so it was basically a hollow tube. So yesterday I proceeded to do the same to the '99 I'm turning into an SM. HOWEVER, in the '99 htere are two vent tubes (probably overflow return) that are either covered or uncovered by a slider that is activated by inserting the fuel nozzel at the pump and deactivated by screwing the gas cap in. The question is whether it is necessary to leave the slider assembly in the throat of the filler tube and/or, what are the consequences of removing the slidder and the overflow vents being open all the time. Thanks
[Smile]

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Bob Reinhardt

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The top line, closest to the filler cap, goes to the TPCV.
The bottom line, goes to the rollover valve and fuel tank pressure sensor.

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Viking Sjovall
Viking Motorsports

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Viking: I appreciate the information. What I have figured out is that these vents are normally open during engine operation and closed while fueling to prevent gas from reaching those valves and sensors. So I can leave the slider out as long as fuel doers not reach the throat of the filler.

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Bob Reinhardt

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My bad. Further reading shows that these tubes are connected during normal engine operations and that the TPCV only is blocked during fueling. I'm thinking I screwed up in trying to widen the filler throat.

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Bob Reinhardt

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Drago ?
What are you doing on your 99's ?

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Viking Sjovall
Viking Motorsports

Karl Verified Driver Made Donation to Website
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Bob,

If you remove everything including the lower one way valve (a strange three piece flapper) you will flood the charcoal canister and the rest of the lines until fuel spills out the right rear tube in the fender well.

We have gutted fillers with the one way valve installed (which does slow fueling) and no problems. If you want to experiment, you can remove the one way valve at the bottom of the filler neck and install a small check valve in the small line that goes to the charcoal. canister. Make sure air flows TO the tank. [Smile]

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quote:
Originally posted by Viking:
Drago ?
What are you doing on your 99's ?

Vacationing in Mexico! [Big Grin]
I just drill out top flapper valve with hole saw and leave the lower check valve intact. I don't run any/many enduros, but as Karl said it does slow fueling. But I have never had any issues doing it that way. The tanks have prod date breaks and late 99's and 00's have another vent line to filler neck as well.
Jim

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Jim Drago
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I gutted my '99 by drilling out the slider assembly. Did I make a mistake by removing the slider? Do I need to make a change before the car's 1st race? I was under the impression that the 2 vents were open during running contition and closed when refilling.

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Matt Jensen
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Other than speeding up the fill process for an enduro race is there any benefits to gutting the filler for a sprint race that we typically do?

Pat

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One more question, if you drill out the slider there still is a check valve in the vent line correct?

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Matt Jensen
SCCA SM Cen-Div
MC NASA 68

Viking Verified Driver Made Donation to Website
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quote:
Originally posted by Drago:
quote:
Originally posted by Viking:
Drago ?
What are you doing on your 99's ?

Vacationing in Mexico! [Big Grin]
The tanks have prod date breaks and late 99's and 00's have another vent line to filler neck as well.
Jim

I think the two vent lines and the little slider that opens/closes when filling were really what Bob was asking about. - Do you take out the slider piece or leave it on the 99's ? Karl how about you - have you removed the slider for the small vent tubes ?

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Viking Sjovall
Viking Motorsports

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quote:
Originally posted by pat slattery:
Other than speeding up the fill process for an enduro race is there any benefits to gutting the filler for a sprint race that we typically do?

Pat

Easier to put a large hose from a fuel jug inside the neck to fill without spilling. No benefit other than convenience and possibly less chance of fuel spilling in paddock.

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Viking Sjovall
Viking Motorsports

soupy
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I removed everything out of mine back in 2006 when I built my car. Have done lots of sprints and enduros including the Nelson 24 hour with no problems.

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Charlie Campbell
Race Engineering
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Thanks to all who have responded. I'm not sure I understand all the comments. Beginning to think this was a can of worms. I'm looking at the workshop manual (page 1-14-20) that shows that air (not liguid) has the ability to go FROM the rollover valve and pressure sensor TO the TPCV during engine operations. Since the rollover valve shuts and cuts off this air in the case of a rollover, I am guessing that this airflow is somehow necessary to tell the TPVC that all is well. More obvious is the fact that the engine does not need to know anything when it is stopped during refueling, all that is realy necessary is a vent and that is an entirely separate tube to begin with (at least I'm assuming when they lable something (breather hose - it is a vent. Since the slider has rubber seats, it does not appear to be open to the ambient pressure in the filler thoat. When fueling the "From" port (lower) is closed, but the "TO the TPCV" port is open. That part I don;t understand, since the placement of the whole slider assembly itself will prevent any gasoline from getting to those two ports - no matter that the positin of the slidder. One suggestion here locally was to just disconnect the rubber tubing from the "From" and "to" vents and connect them together directly - this would give the same configuration as in normal engine operations ands eliminate any possability of getting fuel in them. BUt, what I can not figure out is the roll thay play while fueling or if they have something to do with maintaining fuel pressure.
Soupy's comment seems to be the best direct evidence that it makes no difference.
Some of us ( I think Karl is in this group!) have a harder time just not knowing...

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Bob Reinhardt

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I guess I missed the part in the rules that said you could re-route vapor/fuel/sensor lines.

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Do I turn my 99 Hard S into a killerfast SM or seek a donor?

Dirt Surfer Verified Driver Made Donation to Website
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Good point Kent, but it brings up the idea of "unintended consequences" resulting from what the rules do say you can do. For instance, the rules clearly allow the removal of the filler flap. But, on the '99 if you remove the flap, you have also removed the support for the slider that actually directs the air between these two tubes. So far nothing on this thread has left me knowing just what the effect of leaving those two pathways open to the ambient atmosphere of the filler neck will be. Soupy's comment would seem to say there is no effect. My one option is to pay $87, get a new filler tube and go back to OEM status... I just know from experience how much of a hassle it is to fuel it that way.

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Bob Reinhardt

Dirt Surfer Verified Driver Made Donation to Website
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Well, I came up with a solution no one should be able to take exception to. The slider can be reattached and held in place, making it operational again. It is not particularly hard, provided you have a little patience and have not removed the internal bracket that the slider sits in. What I did was 1) put the slider back in and put two drops of epoxy in the notches where the slider is held in its bracket. Let it dry. 2) carefully put expoxy on the two long edges of the slider - thus really holding it to the bracket 3) (the harder part) - If this is all you do then the fairly common large funnel many people use will in fact dump gas right where you don't want it - on top of the slider. The diagram in the workshop manual makes it obvious that a normal gas pump nozzel will extend beyond the slider. IF you use a long tube you might be able to skip step 3 - but what I did was fabricate a cover for the slider out of very thin aluminum. It can be bent on the sides to grip the outer edges of the slider bracket and once installed, it will not be able to fall down or move up. 4) a very small screw in the top of the slider mechanism allow the slider to be moved up manually - it will go down automaically when the gas gap is put on, but it was the flapper that activated it. If any one else is as O/C as I am - photos available. So, while I'm still interested in knowing if I needed to do this, well, I saved $87 and know I'm legal...

Thanks for all the thoughts. I'm actually surprised that there was no known definitive answer already out there.

On to the next mod.

Bob

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Bob Reinhardt

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Bob,

Not something I'm going to protest anyone about. Sounds like a tedious solution to the problem. Hope it works.

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Do I turn my 99 Hard S into a killerfast SM or seek a donor?

Dirt Surfer Verified Driver Made Donation to Website
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Kent:
I think sometimes tedious is my middle name - I'll go to great lengths for the "elegant" solution rather than just slap something together. This fix will definitely work. My real concern with all this was getting a check engine light and not being able to clear it because of the sensors getting lousy information. I do know from the manual that the slider not being in the down position (airflow going from one tube directly to the other) is what gives you the check engine light if you leave your fuel cap off, so it would seem that nyone running without the slider should be getting that light. I don;t know if it is coverd in the GCR, but I've had tech people not like check engine lights.

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Bob Reinhardt

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That's why you rewire the check engine light to the alternator light circuit.

[duck]

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Do I turn my 99 Hard S into a killerfast SM or seek a donor?

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quote:
Originally posted by Kent Carter:
That's why you rewire the check engine light to the alternator light circuit.

[duck]

Airbag circuit better, alt. light might cause them to check your alt.
[duck] [duck] [duck]

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Viking Sjovall
Viking Motorsports

   

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