cjg454ss

iTrader: (27)

i have a twin walbro, -8 feed to aeromotive rails, aeromotvie pro series regulator and stock feed as return. my question is, my pressure is set at 60psi idle. it will sometimes go to 55 or 65 psi when i turn it on. it seems to start and go to 60psi or start and be +/-10psi. what would cause this? bad regulator

waynehartwig

...Or varying voltage at the pumps. Most likely regulator, though....

Or your pumps are bad and you don't actually have the regulator set at 60, but 65. You might try setting the regulator at 50 and then see if it varies or stays at 50.

..actually thinking out loud again, stock return is what, 5/16"? If you are running two pumps, you might be over powering the return line...

cjg454ss

iTrader: (27)

good point, are those regulators rebuildable. mines about a year old with 20 miles tops on it. all track passes.

cjg454ss

iTrader: (27)

my voltage looked good, the battery is in the rear so it has a short shot to power the pumps. both are running off one 30amp relay. should i run two relays?

waynehartwig

You'd have to ask the manufacture that one...

30A's should be plenty for two pumps at basically 12A each. How big of wire are you running from teh battery to the relay to the pumps? And how far? It should probably be 8 gauge to the relay and then where it branches to the pumps. Then at least 10 gauge to each pump. Also, crimp connectors are terrible. The wires should be soldered and shrinked.

.5 v loss at the pump is a big deal. Crimp connectors or small wiring can cause a lot of voltage loss at 30 amps.

cjg454ss

iTrader: (27)

i think im going to run new wiring and solder them. i have crimps off the relays and then a couple butt connectors in their.

Old Geezer

iTrader: (3)

The Aero series reg is not designed to be used with a 5/16" return line.
http://www.aeromotiveinc.com/d_syste...temdisplay=efi
You don't say if the second pump is on a relay, or they are both running all the time. [Could over run the return]
If you can't adjust the reg to at least 5psi lower than desired setting, you may have a return line problem, such as:
Kinked.
Insufficient size.
Incorrect entry into the tank.

cjg454ss

iTrader: (27)

i do run them both all the time, i can regulate it down to 40 im sure of. i though the stock feed was adaquate for the return. im giong to check the return for any issues tonight.

Old Geezer

iTrader: (3)

OK. With the reg adjustment being capable of going down to 40, I'd say that's not the problem.
Have you verified that the gauge is OK?
If it's one of the little, "silver dollar" sized rail gauges, it could be the problem. I've checked many of them against the gauge on my inj bench.. Some are not within 5psi of correct, and do not repeat well, either.
Wayne may well be on the right track w/ wiring issues. Have you checked the exact voltage at each pump? How are the pump grounds done?
What's the part # on the pumps?
Does the -8 feed the rails first, then out of the rails to the regulator?

cjg454ss

iTrader: (27)

the feed goes to the driver side rail and crosses over and feeds the pass. rail then to the reg. the pumps are spliced together with a butt-connector and then grounded to the body. twin walbro 340. again the base pressure is good most of the time 2,3 out of 10 starts it will just be all wacked out, either 50psi or 70. i have an electric in the piller and a manual gauge on the regulator. i go to the regulator and adjust the pressure and it seems fine. maybe the spring is getting stuck or backed up from the small return? possible?

waynehartwig

I like your thinking, too... I've got one of those crappy rail gauges from Summit and it always shows 44 psi, and I run a Corvette filter/regultator.

I'm leaning towards either wiring or return is too small. 5/16 is awful small for two larger pumps.

Try killing one pump, set the regulator at 58 or whatever, then see what it does. If that works, then rewire the pumps and run a second relay with a switch in the cab where you can turn it on when you need it. I'd say upgrade the return, but you don't really need two pumps running all the time anyway.

cjg454ss

iTrader: (27)

^^thanks for the info, tomorrow im going to rewire it i think if i have time or atleast shut one off.

waynehartwig

I'd try just shutting one off for now. If the wiring is fresh, chances are pretty good you don't have much of a voltage loss going on. Besides, if it's over powering the return, fixing the wiring will only make it worse. Killing a pump is fairly quick and easy and you'll see immediate results.