[TitaniumTT]

Thanks for the tip. It looks like I may need a new pump afterall.

I'm still not having any luck finding a lab that can disect a filter. Everyong can do a fuel sample, but not a filter. I know the contamination is in the filter, not sure about the fuel.

Anyway, an excerpt from my build thread -

Pulled the pump and hooked up a wire to both the ground on the hanger and the hot on the lid. Checked Bat voltage - 12.12V. Turned the pump on and probed those two wires so I could get a reading of what the pump was seeing with it in fuel and running - 11.12V. Not bad but still something not 100%. I've got a 10GA wire going from the bat to a 20A breaker like 6" away, and then the same 10GA running to the relay on the shock tower, and then 10GA running to the connector which I replaced with a weatherpack. So there is stock wiring from the connector to the pump. Not much but it's still some.

Next I hooked up an Ammeter and ran the pump. 12.51A. This is not good. It should be around 8-9A. This is interesting. I jumped the ground directly to the battery and got the exact same A reading. OK, so it ain't my wiring although there is a loss somewhere, most likely just the resistance of the connectors, breakers, relays ect ect.

The sock looks a little meh so I pulled the sock to eliminate that as a source of vac and got a reading of 12.46A. OK, so a questionable sock only adds a slight amount of resistance. This is interesting. Questionable meaning you pull the thing out of the tank and fuel is still being held in said sock.

OK, well, maybe that filter really is clogged. I'm still seeing ~ 43psi with no laod, but what if it isn't? That's a TON of A's for a pump to suck down. Alright, we need to know without a doubt that this filter is fucking me. So what do I do you ask - go on, ask. Alright alright, I'll tell you. I have a spare 250psi sender that I use for my comp tests. I dug through my binS worth of fittings and found a -6 male to -6 male with an 1/8"npt port, an 1/8" to -4 fitting. A -4 female to -4 female hose, a -4 to 1/8"FNPT and put my sender on the end of that. Then I got a coupler and spliced this hodge podge contraption between the hardline and the filter BEFORE the filter. The sender happens to be the same as my Oil Pressure sender ('cuz I get ~ 125 psi >3500) and turned the pump on. Read 43.2psi at the regulator. A little high. Even more interesting is that it read 42.6 - yes Forty-two and 6/10 psi BEFORE the filter. Interesting. There is a negative pressure drop across the filter. This could be because of a few things. The Fuel PSI sender is a 0-100 psi unit so the resolution on the 250 psi unit isn't nearly as accurate becuase they are using the same 5v. There is also some sender accuracy, -4 line for the prefilter and a few feet of it, -3 and 10" of it for the after filter plumbed intot the reg. I don't know what the acceptable sensor variations for the autometer (Delco) stuff is but it's OEM so it should be pretty damn accurate. So....... interestingly enough it appears that the filters are only partly to blame. I think the Cosmo pump that I've been using just isn't up to snuff for the pressures that I'm asking of it and the schmeg that was pumped through it in the beginning. I'm going to borrow my buddies Walbro tomorrow and toss it in and do the same tests. I know that the Walbro 392 HP draws just ~8A at ~57G/hr @ 12v. At the highest pressure I'm asking for it draws ~<9A and flows about 52G/hr @ 12V. At 13.5V it should flow ~62 Gal/hr. Assuming 100% duty cycle I need 55G/h. So the Walbro 392hp will actually definately work for me.

(edit - although it's noisy - I'd rather have the Apexi that Jack suggested)

The Cosmo pump has been tested to put out 66 G/hr @ 43psi @13.5V HOWEVER, it was never really designed to put out the kinds of pressures that I'm asking for. I wonder if the pump isn't just falling FLAT on it's face on the higher levels of PSI. Also, this is with a filter with 150 miles on it. I know for a FACT that I have had outright clogged filters and socks from the epoxy coated tank. I wonder if all the shit that went through there didn't fuck up the pump itself. Also, lets not forget that the pressure that I was getting before the filter was never recorded until now. It's possible that the line pressure got into the 80's. The pump way overworked got hot and FUBAR'ed itself. All sorts of shit could've happened but the Cosmo pump that I have, just isn't up to snuff right now. That's also evident by changing the filter yesterday, making one pull and on the second it just went to shit. We spent probably 3 hours on the dyno making pull after pull after pull. It's entirely possible that a questionable the pump "heatsoaked" if you will.