xj6 purge valve / air bleed valve

[eschneider]

On my $150 '79 XJ6, I'm getting rid of the dual tank system and the switchover valves, etc. Basically I removed the switches and tees, but I'm not sure quite what to do with this bit - supposedly its a "air bleed valve" or "purge valve" that maintains pressure in the line for quick starts.

Obviously there is an inlet from the pump, an outlet (with 1-way valve) to the fuel injection rail, and a sencond outlet to the fuel return system.

My gut is to simply remove it (replace it with a straight section of hose). The only consequence that I can think of is that it might take a couple of starts to build pressure in the sytem, and run any air bubbles through the fuel lines......

Am I getting into trouble? Should I keep it and just plug the outlet to the return line (thus keeping the 1-way valve intact)?

Yes, I posting this on jag-lovers too (but I like this group better)

 

[jessebogan]

This is the check valve. It hold fuel pressure in the rail. I don't get wghat you are doing exactly. Keeping the FI, and going to a single tank, or losing the injection totally. Reason I ask is this, one of the tasks of this device is to hold rail pressure, and that keeps the fuel from boiling in the lines, preventing vapor lock and related maladies. It also holds fuel up for much quicker starts in all conditions.

 

[DrEntropy]

hmmm. To maintain the rail pressure (28~32 PSI, IIRC) you want to keep the valve, Eric. If you've "unrouted" the plumbing to one side, just be sure the recirculation line is going to the tank you're using. :wink:

There's a timer to run the pump for some few seconds before you engage the starter position on the iggy switch (to pressurize the rail) but if it were mine, I'd keep the valve. Otherwise you'd need to off/on/off/on the iggy a few times to get rail pressure up to trigger point.

Let's see if Jesse concurs. :laugh:

 

[eschneider]

I'm keeping the FI. Same system as my Fiats, so it must be good.

Gah. I *almost* said that with a straight face. Actually, they're not terrible injection systems.

My understanding is that the valve switches one way (to the fuel rail) when the pump is operating, and switches the other way (return) when there's no pressure from the pump. I don't understand why that's a good thing, but....

I've already modified the fuel return lines and removed the tees, so it would be a bitch to re-connect this thing to the return line, but I guess it's possible.

I can't see how a one-way-valve would affect fuel pressure with the car running (maybe I'm missing something). And since there is a return line, I can't see where vapor lock would be a problem (and I certainly don't get the fuel cooler bit)....

Holding fuel for quicker starts - that I understand and am happy to sacrifice. Doesn't bother me much. Already removed the cold start injector and related bits, so it takes a couple turns o-the-key anyway.

This is why minimalist Morgan guys shouldn't own Jags..... What's that bit? makes it easier to start? A luxury? Convenience? Aww, chuck it.

 

[eschneider]

For posterity's sake...

I removed the purge valve (again, I am doing a single tank conversion with the original FI system here) and it starts right up. Might take an extra second to start if at all.

The cold start injector is also removed/plugged off. It is currently mid-30's (farenheit) in Philly - no problems starting.

If I later experience vapor lock or some other malady, I will update this - but since the valve is always in the "open" position when the pump is operating, I'm not expecting problems.

My single tank conversion seems to be complete.