Quote:
Originally Posted by AustinBelair
Wait I thought the 6 port was for Diesel and 3 port for gas? Would AC Delco ACDelco U7000 work as well?
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Look up the Specs on the Delco U7000. It's likely the same valve but not necessarily. In 2004 my U7000 was a Pollack 42-159. Delco has been sourcing China, Southeast Asia, and Indian parts of late so all bets are off.
Three port valves are for fuel systems with no return line Period. I'm not sure any of the gasoline engine squares after 1980 were manufactured without a return line.
Diesels MUST have a return line. The DB2 Injection pumps on the AMG 6.2L & Oldsmobile 350N & 350DX diesels control cold injection timing advance by restricting flow from the Injection pump to the fuel return line via the HPCA (Housing Pressure Cold Advance) solenoid. Without a return line the DB2 Injection pumps would inject fuel for an ignition point 3° advanced at all times.
Quote:
Originally Posted by donw1986
I put a msd atomic in my 86 with dual tanks, no problems, the transfer valve is good to 65 psi in the later model trucks, the earlier years it wouldnt work , really wasnt difficult to do every thing works fine my truck had steel lines i used the recomended fuel hose thst came with the msd kit, and changed all the short hoses that go from the sending units to the tansfer valve, the hardest part to figure out was mounting msd pumps on chevy sending unots pyt that wasnt to hard
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Swapping a 73-80 over to motorized valve isn't rocket science. Get a complete 1981-1991 NL2 dual tank harness with the switch and the valve then install it.
ON all years... The NL2 dual tank harness is separate from the main engine harness. This meant that the assembly folks didn't have to pick a different harness for the dual tank trucks... just be sure the hole was present in the dash, add on the NL2 harness etc and continue. The single-tank fuel sender wire connects to the fuel gauge output wire on the NL2 harness, usually on the RH frame rail, and the NL2 sender connectors plug into the proper senders.
Three comments on hoses.
-In order of preference use German Fuel Injection hose clamps or constant tension band clamps or Oetiker hose clamps on your fuel hoses.
-Be sure the hose in the tank is SAE J30R10 fuel submersible hose inside the tank. If it doesn't state SAE J30R10 then get 6" or a foot of the real thing. You don't want to have drop the tank because the hose failed.
-Be sure to use SAE J30R9 "Fuel Injection" hose between the senders and the engine connections. J30R10 isn't rated for use in the open air and J30R7 wasn't rated for the fuel pressure when it was still approved as liquid fuel line.
More on SAE hoses and clamps here.
http://67-72chevytrucks.com/vboard/s...d.php?t=696742
Quote:
Originally Posted by Popeye75356
I know this is a super old thread nonetheless I'm about to install the Pollak 6 port high pressure valve PN 42-159 to satisfy the return and high pressure requirements of on my 5.3L, with this said my question is why would I need to change out the wiring harness as the pig tail looks to be identical to the original?
Also, does anyone have wiring instruction for the in-tank pumps, I've installed them on 87' sending units but not sure how to wire up the pigtails ?
Thanks in advance!
Popeye
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If you're doing in-tank pumps you'll need the 1987-1991 R/V series TBI fuel tanks and TBI NL2 harness with the correct connections to the fuel pump. The TBI senders have 2 position Weatherpack disconnects that have Pump Power and Sender wires. The TBI sender and Fuel pumps complete the circuits using the tank to frame ground.
If you're running in-tank pumps use the 1987-1991 TBI tank switch.
This is the NL2 schematic for a 1989 RV 10-30 with TBI. The 1987-1991 Diesels do not have the in-tank pump power wire provision. You can see the part numbers for the Weatherpack shells and the extra power wires teed off the Gray and Tan D & E wires at the valve.
It's worth noting that a pump shutoff provision should be added for safety. GM TBI systems used an oil pressure switch, relay, and the ECM to shutdown the fuel pump. You'll need to dig into the 5.3L PCM schematic for the fuel pump relay output wiring. It's safer to do this. You don't want the fuel pump to run after the engine shuts down in an accident.