Fuel Pump Problem??

[nacho55]

Little on my Project, it is a 02 5.3 with a 5 speed, and modified harness, and a blazer tank with a AC Delco EP381 Intank Fuel pump, (or I think thats the pump), in my 55 first series truck, its been running a little over three weeks now and I have put about 800 miles or so on it now and it runs great, but the last couple of times I have taken it out, it stumbles and even stalls but will start right back up and idle normal, but then stumble when your driving like its out of gas untill I drive it for two or three miles, then it drives like normal. but if it sits for a couple of hours it will act up again but not as bad like when it sits over night or a few days. I have a serviceable fuel filter that i have cleaned a few times and there was some crud in the filter element but it wasnt completly cloged, could the pump be going bad, or not enough pump, or bad regulator on the fuel rail?
Any thoughts would be great
Thanks

[TopFuel1966]

Pull the vacuum hose off the fuel pressure regulator. If gas runs out of it the regulator diaphram is ruptured.

[nacho55]

Thanks for the tip, ill give that a try tonight when I get home, could a faulty regulator hurt the fuel mileage, mine doesn't seem to be getting more than 10, but then again I don't baby it ether .
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[ls1nova71]

What's your fuel pressure? And out of curiosity where did you get a serviceable high pressure filter? All the ones I've seen were for low pressure carb applications. Just wondering out loud, but could it have come apart inside?
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[nacho55]

Originally Posted by ls1nova71

What's your fuel pressure? And out of curiosity where did you get a serviceable high pressure filter? All the ones I've seen were for low pressure carb applications. Just wondering out loud, but could it have come apart inside?
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I used a trickflow specialties billet inline aluminum filter I got through summit, says its rated for 300 psi and capable of flows up to 130gph , I used 3/8 line with all -6 fittings. But I've taken it apart a couple times now and it looks intact, Ohh and I haven't checked pressure yet ill have to find something to hookup to check that.
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[nacho55]

So it looks like I have a regulator problem, I first unhooked the vacuum line to check for fuel or fumes or anything like that and I didn't see or smell any while it was running hooked the line back up and shortly after the engine stalled while I was trying to hook up the pressure gauge, so I started it again and it stalled, I hooked up the pressure gauge and started it up with the vaccum line off and it read almost 60#s the dropped to 58-59, then I hooked the vacuum line back up and it dropped to 48-49 pounds and would go up to almost 50 when I rev-ed up the motor, so I un hooked the vaccum line again and it jumped back to about 58#s , looks like I will be replacing that soon, also a little cheap tool trick since I didn't have the actual fuel pressure gauge and didn't want to spend any money to buy one I used an old R12 ac gauge had the same fittings all I did was remove the scharader valve from the line and hooked it up worked like a champ for nothing.
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[nacho55]

I figured I would update the problem I was having incase someone else started having the same trouble, what I thought was a regulator problem after swapping in the new one the pressure was a little higher but kept stalling and stumbling after restarting it several times it acted worse than before, long story short turns out my main ground wires off the harness that I had bolted to the block wasn't tight and got looser from the motor running, tightened it back up and it runs great again, so check your grounds
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