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It looks like it's time for a new fuel pump - '97 STS


KHE

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It can be any of the wires....inside or outside of the tank. It can be at the top-of-the-tank connection or the harness inside the tank between the connection and pump.

Nothing worse then dropping the tank....install a new pump. Only to have to drop the tank again to replace the harness.

It can be at any of the yellow arrows in the picture....it can also be in the (body side) plug that connects at the top of the tank.

Is the harness shown in the picture (with a connector only at one end) the one that goes from the top of the fuel pump to the side of the tank? If so what is done with the ends that do not have the connector? Or is there a separate harness available? My thought is to just replace the pump anyway even if it is just the wiring since the pump has 194,000 miles on it but I want to have all the parts on hand so I can complete it in an afternoon.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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The Delco pump pic was a generic one pulled off Google. So I don't have an answer of what will come with the pump.

Many pumps will come with with some type of harness for this issue.

It's cheaper to send out a new pump with a small harness then to have a good pump returned as 'no good'.

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1997_Fuel_Pump_Relay.png

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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The only connectors that I see are C415, the fuel pump connector (and also the gas gauge sending unit), and C101, which is a connector onto the mass of wires at the underhood Maxifuse/fuse/relay center. There don't appear to be any other wires on S481 or S185. The other things that share ground G401 through splice S402 are vast. Right/left rear door cigar lighter, RR/LR door courtesy light, RR/LR power window switch, power door lock relay, and much of the electronics bay and fuse/relay centers on the rear of the back seat.

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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The schematic is missing some critical wiring. I think they are showing it as 'fuel tank unit.' Assuming that any problem with the 'unit' it is replaced as a complete unit. Wires, pump, bucket and all (see post #24). So the schematic shown dead ends at the top-of-the-tank connector...

Counting 2 wires...there are 6 connectors between the top of the tank and the fuel pump that can fail.

post-2-0-96140700-1412297136_thumb.jpg

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Thanks for the information, guys. My guess is that there are some overheated connections that are between the connector I can see and the fuel pump and that is what is causing the high resistance and low current draw of the pump. The pump draws 2.5 amps and my Deville draws 6 amps so I know there is high resistance in the pump circuit between the main connectoe at the tank and the top of the pump.

The pump harness is no longer available so I'll have to see what I find when I drop the tank. I think there is enough on the aftermarket as far as wiring goes that I can fabricate a new harness from the top of the pump to the side of the tank.

I am tempted to drop the tank, pull the pump and check the wiring but I'm going to hold off until all the parts arrive so I only do the job once. I am running the tank low on fuel and when I get ready to drop the tank, I plan to disconnect the fuel line at the fuel filter and use the fuel pump to pump out the rest of the fuel into a gas can.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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The schematic I posted is limited to the fuel pump. If you think that the other fuel tank items on the same connector are important to your issue I can post those schematics too.

The only thing between the fuel pump and the relay is two splices with no other wires on them. Those rarely give problems unless the wiring has been wet for a long time or some such. I can locate the splices if you like.

The weekend is coming and I can give you anything you need.

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Thanks Jim. There is a short harness that goes from the top of the fuel pump to the side of the fuel tank where the harness to the relay plugs in. That short harness is the one that is no longer available. There is also the possibility the wires between the top of the pump and the motor have overheated. I won't know until I drop the tank. I ordered the parts last night and won't have them until late next week.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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... There is a short harness that goes from the top of the fuel pump to the side of the fuel tank where the harness to the relay plugs in. That short harness is the one that is no longer available. ...

This would be the wires between the fuel pump and C415, which is near the leveling pump (FSM p. 8A-201-52, fig. 95). The connector is a 4-way Metri-Pack 280 series (p. 8A-202-29) that has the fuel pump on the center two connections. The side with the clamp and cover is MD GRY, the side with the hook and connectors in a plug that goes into the hole is GRY. There may be some side hooks as well as the plastic clamp. Other numbers on the connector diagram are a date and EV3148A202, which is probably a drawing number (note 8A202, the FSM section, is in that number) but may help you find a new connector. Number under the MD GRY side 12129565, number under the GRY side is 12129600; these probably are part numbers although I would expect one part number for both sides of the connector.

I would expect this harness, with the MD GRY side of the connector, to come with the fuel pump and/or the sending unit, because the other end connects to these items. But I recall that one of those connections to the fuel pump inside the tank was a point of failure for the 1997 model year; it failed on my car and I got a new fuel pump on warranty, so it does plug in, at least on early production. I would consider soldering that connection.

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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I just had an overdue thought: a recycling yard harness that has C415 intact would do just fine because you will want to solder the other end anyway. If the new fuel pump/gas level sensor doesn't come with the wire to C415, that's your answer.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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I just had an overdue thought: a recycling yard harness that has C415 intact would do just fine because you will want to solder the other end anyway. If the new fuel pump/gas level sensor doesn't come with the wire to C415, that's your answer.

Always good to keep the options open - thanks!

The fuel pump comes with a connector pigtail. It is possible the bad/overheated connector is the one at the top of the pump but as Logan said, it can be at the areas marked with the yellow arrows in the picture. Since I'm going to replace the fuel pump, that will rule out the ones inside the tank. The connection at the side of the tank looked fine - if the one at the top of the pump was overheated, I'll be set with the included pigtail. I will definitely solder the connections and use heat shrink tubing.

I plan to replace the fuel filter also so I sprayed the fuel filter threaded connection with "Break Away" this morning. I'll hit it again tomorrow. The tank side of the filter is a quick disconnect but the engine side is threaded. Hopefully, it comes apart without any trouble.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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In the new 1997 models, there was a common problem with the connections at the fuel pump overheating; my car had that problem at about eight months and the fuel pump was replaced on warranty. In an older car, an electrical problem can be anything but is usually due to wear or damage. With that, unless something is damaged outside the fuel pump, my money is on internal wear in the fuel pump has gotten to the point that internal drag makes it draw too much current for the wiring. That would account for low fuel pressure, without the total dropouts to zero fuel pressure that you see with bad connectors. Also, if you get everything in Logan's picture with the yellow arrows, you will have everything you need.

Be sure that the solder you use, including its flux, and the heat-shrink tubing, are all OK for permanent immersion in gasoline.

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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In the new 1997 models, there was a common problem with the connections at the fuel pump overheating; my car had that problem at about eight months and the fuel pump was replaced on warranty. In an older car, an electrical problem can be anything but is usually due to wear or damage. With that, unless something is damaged outside the fuel pump, my money is on internal wear in the fuel pump has gotten to the point that internal drag makes it draw too much current for the wiring. That would account for low fuel pressure, without the total dropouts to zero fuel pressure that you see with bad connectors. Also, if you get everything in Logan's picture with the yellow arrows, you will have everything you need.

Be sure that the solder you use, including its flux, and the heat-shrink tubing, are all OK for permanent immersion in gasoline.

The existing pump is drawing too little current - only 2.5 amps vs. 6 amps of a normal pump. That is what makes me think one of the connections on the pump module or the pump motor itself has high resistance. The only soldering I would need to do is outside the tank on the harness that connects to the top of the tank.

http://www.rockauto.com/catalog/moreinfo.php?pk=293345&cc=1027831

with the new style pump it comes with a harness, just add on to your existing harness.

I purchased a new AC Delco fuel pump module off ebay from a GM dealer in Kentucky for $30 less than the Delphi (OE manufacturer) unit Rockauto had. It also comes with a new harness plug. I'm not sure if I should just replace the pump end or just inspect the harness and if it shows no signs of overheating, just re-use the existing harness. I may do some voltahe drop tests with the tank lowered to see what I can find.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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The parts arrived today. The fuel pump had part no. 88962476 (AC Delco MU156) and the part no. 19153726 was written over the label. Apparently 19153726 replaced 88962473 but the issue is the 88962473 has a 4-wire square socket and the 19153726 has a 4-wire flat connector. This fuel pump did not come with a harness pigtail. I need to call the part supplier and find out what the deal is before I drop the tank. My guess would be the car has the square connector but if the harness is burned, I won't be able to connect it.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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the harness inside the tank likes to burn up. I find it to be less common for the one on top

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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the harness inside the tank likes to burn up. I find it to be less common for the one on top

Are the top connectors on the ones you've worked on the square 4-wire connectors with two pins on top and two pins on the bottom or are they 4 pins in-line in a single row in a rectangular connector?

My concern is that I will go through the work of dropping the tank only to either not have the correct electrical connector or that my existing one is overheated and in need of replacement. I also am thinking that I was sold an obsolete part no. that does not have the upgraded wiring that is internal to the tank...

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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there is both. 4 pin square is for the pump and sender. the other is for the tank pressure sensor ( if equipped)

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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I called AC Delco and the pump I was sold was the original design - it does not have the upgraded wiring which is marked by the flat 4-pin connector atop the pump. The part was advertised as a 19153726 which is is not. I need to send this one back and get the one that was advertised. Looks like I won't be R&Ring the fuel pump this weekend.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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I would guess that the "$30 cheaper" was because it was the old part. I've had that experience with cell phone batteries and printer ink; if you shop around online and find a really good price, you will usually get one at or near it's expiration date. NiMH batteries last 5 years, in use or not, and out-of-date printer ink gives my printer indigestion. I've found entrepreneurs that don't know this when they go buying overstocks to sell one-by-one on eBay or even sites like Amazon, and they find out from their customers that they have been burned in their bulk purchases.

But, the people that you bought the part from apparently printed up a bunch of Avery labels and put them over the part number on the box.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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The current number (19153726) was written in marker over the label that was printed with the part no. 88962473. I spoke to the seller earlier this afternoon and he stated they purchased a quantity of parts from a dealer that closed. He refunded my money and told me to throw the part out. I told him I'd send it back if he'd send me a UPS label but he said it was not worth the postage to return it.

I'm tempted to just install it.....

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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can't hurt it's free!!

That's what I thought. I will leave the seller positive feedback because he made it right for me.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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The current number (19153726) was written in marker over the label that was printed with the part no. 88962473. I spoke to the seller earlier this afternoon and he stated they purchased a quantity of parts from a dealer that closed. He refunded my money and told me to throw the part out. I told him I'd send it back if he'd send me a UPS label but he said it was not worth the postage to return it.

I'm tempted to just install it.....

I would cross out the marker and write the real part number under it, and send it back UPS ground and watch the tracking number every day. That's the best $10 you could spend for harmless entertainment.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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I find that people cross out the old stock number and put the current number because the current one is the one that sells.

Basically if you call the dealer they will give you the most current number, so you will research that number most likely.

I would install it and not even think about it lol. For free

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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