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-   -   fuel pump electrical supply, 1984 T-Type (http://gnttype.org/forums/showthread.php?t=16852)

carlu 07-13-2015 04:50 PM

Re: fuel pump electrical supply, 1984 T-Type
 
RockAuto lists the SpectraPremium FG156A sender, strainer, and float for $91.79. FG156A is claimed to fit 1984 through 1987.

The FG156A part listing does not mention digital fuel gauge or analog fuel gauge. Are there different senders for the two applications?

There is one offered in our Parts For Sale but it's described as for an analog gauge.

kenmosher 07-13-2015 04:53 PM

Re: fuel pump electrical supply, 1984 T-Type
 
Yes, they have different resistor values in the sender, from what I remember.

carlu 07-15-2015 03:34 PM

Re: fuel pump electrical supply, 1984 T-Type
 
Reading various postings online and the scanned Turbo Regal parts book online, I see for the 1987 GN:

meter, fuel (in tank)(3.8 - 7)(EXC U52) 25092745
[metering unit, 90 ohms full scale, for analog fuel gauge]

meter, fuel (in tank)(3.8 - 7)(W/ U52) 25092748
[metering unit, 120 ohms full scale, for digital dash (U52) fuel gauge]

The SpectraPremium FG156A part is 90 ohms. I read complaints that some finesse is necessary to get it to fit in a Turbo Regal tank (assuming that means an OEM tank). I have a replacement SpectraPremium GM307 tank.

So I'm looking at buying the new sender unit in order to get rust-free fuel pipes. I could transplant my old (but cleaned up) fuel-measuring rheostat and anything else needed to make it a 120 ohm unit.

carlu 10-07-2015 04:49 PM

Re: fuel pump electrical supply, 1984 T-Type
 
I patched up the main fuel line coming out of the sender assembly at the top of the tank.

New tank, new straps, new bolts, new intermediate lines to the rubber cushion area above the rear axle.

New return line up to the front of the car. Main fuel line was replaced ~1998 and still is OK.

Fuel pump does not prime for a few seconds at key on. Fuel pump runs off lawnmower battery.

With the fuel pump fed off the lawnmower battery, the car started and ran. Idle was very poor. It didn't want to rev much with throttle input, but did rev a little while releasing throttle. Days later, I tried to repeat this, but the engine would not fully fire up... just sputtering. Fuel pressure is about 35-40PSI at the fuel rail test port.

kenmosher 10-07-2015 04:56 PM

Re: fuel pump electrical supply, 1984 T-Type
 
Check fuel pump relay and oil pressure switch (for the non-priming problem).

The pressure sounds good, but the rough running/no start almost sounds like something electrical:
  • Check to see the battery voltage is good ... more than once I've been bitten by low voltage ... the wiring is getting old and brittle in these things
  • Check the grounds at the back of the block/head and the battery strap ground at the bottom of the turbo mount. Bad ground = all sorts of chaos
  • Check the cam sensor clocking and the interrupter ring inside ... if it wiggles or is loose, that's a problem
  • Injectors may be gummed up or bad from bad fuel/old fuel residual
  • Check for good spark ... Casper's coil tester is pretty handy for that
  • Check plugs

That's kind of a brain dump ... hope it's something simple like a ground.

carlu 10-07-2015 08:08 PM

Re: fuel pump electrical supply, 1984 T-Type
 
Found good continuity on tan wire from body harness connector at tank, to fuel pump relay connector tan (or is it gray?) wire.

FYI, in case someone else has this problem:
A long (10 feet?) wire helps make this test. Insert a wire into the fuel pump body harness connector and lay it just right, so that the test wire touches the exposed harness pin in the WeatherPack connector. Run that wire all the way to the engine compartment, to allow checking continuity to the relay harness connector near the passenger side fender, using an ohmmeter.

Next, I jumped the relay hot (pink-black) to relay load output (tan, or gray). The fuel pump energized and brought the fuel rail up to about 38psi.

I guess I have a bad fuel pump relay. On my 1984 Regal, the OEM relay has part number 10027719. There is brown greasy stuff on the wiring connector that plugs into this relay and also the connector for the A/C cutoff relay next to it on the passenger-side metal bracket.

carlu 10-07-2015 08:17 PM

Re: fuel pump electrical supply, 1984 T-Type
 
With cranking the engine, it sputters, but won't run.

A few days back I had it running very poorly (ran with a sound like pup pup pup...). I fiddled with the wires and connectors on the front of the engine below the coil pack. This made it almost stall. :idea:

Today, same crank - sputter - won't run. I felt around the coil pack, and found a harness connector under the coil pack, that has wires that lead up toward the intake manifold. I felt it un-mate while poking around in there.

After plugging it back in, the engine started and ran! :winkgrin: ! :winkgrin: Pretty smooth for the engine not running for several years!

I think rodents have been trying to disassemble my wiring harness wire by wire. To make a nest. Or to sell it on ebay.

mikeelia 12-02-2015 04:27 PM

Re: fuel pump electrical supply, 1984 T-Type
 
It happens! And those gremlins [not the AMC kind] come around every so often as well, just to see if you are paying attention to the old Buick... LOL


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