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IP lets tons of fuel exit to return system

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Old 09-01-2015, 11:02 PM
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IP lets tons of fuel exit to return system

Ok so it's been a crappy ride with this Pensacola Diesel IP I've had for some years. I'm close to getting a new IP but wanted to see what you guys thought first on this issue.
I recently upgraded to the Facet Duralift r-pump and deleted the stocker, thinking it was the problem. I have a different thread about how my input pressure was horrid with those pumps.
Anyways... It didn't solve the problem. I have a gauge set up in the stock filter header return port, so I always know what the pressure is and once the fuel gets hot she doesn't see more than 3psi, with the Duralift rated at 9-11psi max.
So I put a jar on the end of the IP return hose thinking it was puking fuel out and I was right. Almost 12oz just idling in a few seconds! (So I can't build any inlet pressure because I don't have anything keeping it in the IP, it just goes right through it)

So I guess my question is, does that indicate internal failure/issues, or just something screwy with the return hardware, specifically that electric check valve thingy? It's working, as is the little check-ball it pushes up when cold, but maybe there is a seal between them I'm missing? In comparison the previous (stock) IP running at freeway speed took 10 mins to fill a 16oz container.

Another note, I've read other posts where guys capped that line and ran the IP fine at least for a time. My pickup won't start with the line pinched and once running hot, will barely run at all if I pinch the line. I pinched it "halfway" or more with some vice grips, I could dial in the flow that way with more or less jaw pressure. However it ran even worse no matter what I did.

Thanks,
Joshua
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Old 09-01-2015, 11:46 PM
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Well, yes. It's supposed to be that way. Unused fuel is returned, and timing advance is done hydraulically, between a boosted input pressure and the "housing pressure".
Once it is warmed up, the "housing pressure" should be 5 PSI. Any more fuel that goes into the housing gets returned via the return line.

If you restrict your return line, you increase the housing pressure == you retard the timing. Not so good.

Now, the one thing you might look into is called the "vent wire assembly". This is internal to the pump, and is what allows the fuel to flow from the input side to the housing/return side. If it is missing, you would get a ton of extra fuel there.

This being said, my new, RD2-110 pump does exactly the same thing. It returns a ton of fuel.
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Old 09-02-2015, 01:18 AM
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IP lets tons of fuel exit to return system

3psi at the filter is my hot max at idle... And once I touch the throttle it goes mostly to 0psi.
Unless I'm missing something there's no way the housing pressure could be 5psi with 0-1psi feeding it.

Got a pic or diagram of the vent-wire assembly?
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Old 09-02-2015, 09:10 PM
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Old 09-04-2015, 04:17 PM
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IP lets tons of fuel exit to return system

Thanks for the vid, I've seen it before but certainly can't remember all that!

I'll have to check on the vent wire, should be there on a stock rebuild like mine.
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