6.2 fuel sending unit problems - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Adam j · 03-12-2018, 08:48 PM

I'm changing the sending unit on my 6.2 and can't find one like it it has 3 outlets and one plug for the gauge and a exterior ground and two of the outlets go into the tank are long and one is short I can't find another like it anywhere it is a old military truck so who knows what it's from and when I look at the one it recommends it has two plugs and the ground is internal please help thanks
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andyh1956 · 03-12-2018, 10:16 PM

Try a Spectra FG05K for driver side or FG05L for pass side.
For surplus try Hillbilly Wizard or Ted's Trucks & Stuff.
These are for M1008 but may be the same for M1009.

Adam j · 03-13-2018, 01:36 PM

Quote:

Originally Posted by andyh1956

Try a Spectra FG05K for driver side or FG05L for pass side.
For surplus try Hillbilly Wizard or Ted's Trucks & Stuff.
These are for M1008 but may be the same for M1009.

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Adam j · 03-13-2018, 01:37 PM

Quote:

Originally Posted by Adam j

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Those parts don't match the one I have I tried them thanks for the help
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andyh1956 · 03-13-2018, 03:19 PM

When you say two plugs that's electrical plugs correct?
Will your wiring harness plug into one of the plugs or do the wires need to be "Divided" between the plugs?
You have an M1008 or M1009 or is your tank just from a CUCV?

sweetk30 · 03-13-2018, 05:35 PM

post up some pics of what ya got . see if I can match it.

I have 2 tanks with senders from a diesel truck I parted .

looked up for 1985 k30 6.2 diesel . verified 1984 - 1985 - 1986 the vintage of almost all military trucks of this style take the same sender listed . unless military did a weird custom thing .

driver side 3 port https://www.rockauto.com/en/moreinfo...053065&jsn=459

pass side 3 port https://www.rockauto.com/en/moreinfo...053065&jsn=458

these what you looking for ?

1 plug/pin is sender feed . the other is water in fuel ? if I recall.

short is tank vent / 5/16 is return line / 3/8 is fuel supply . ground is flat spade on 1 of the lock tabs in the pic .

Adam j · 03-13-2018, 05:47 PM

It is a m1008 and the sending unit looks like the ones from rock auto but the ground is just on the outside and the top only has one spot for the wire for the gauge to plug in the rock auto one has two
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sweetk30 · 03-13-2018, 05:52 PM

military might have NOT run water in fuel then so no need for 2nd wire to be used .

all these gm senders were external ground also .

unless you find one like you got then just run a reg one like I posted up .

or go try finding some info over on www.steelsoldiers.com . free site but tread light . make sure you look and post in the correct place .

Adam j · 03-13-2018, 07:21 PM

Quote:

Originally Posted by sweetk30

military might have NOT run water in fuel then so no need for 2nd wire to be used .

all these gm senders were external ground also .

unless you find one like you got then just run a reg one like I posted up .

or go try finding some info over on www.steelsoldiers.com . free site but tread light . make sure you look and post in the correct place .

So the other plug on to that has the wire in the tank is just to tell you if there is water in the tank? And I don't have to use it ? I was not sure what it was for I thought it was some kinda of ground
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sweetk30 · 03-13-2018, 09:36 PM

should be a separate thingy it hooks to for water in fuel light . must not come on new senders .

andyh1956 · 03-13-2018, 10:19 PM

The CUCV trucks had a "Fuel Management Center" filter on the firewall w/ fuel heater / water in fuel sensors in it.
I would bet the extra plug is for an in tank gasoline pump. The new senders are prolly universal in nature & use the same one for diesel, just w/ the pump omitted.
Just guessing here though.
I have a '86 one ton diesel frame left from a truck that I had a mini van drive up into the cab with me up behind the barn. Tomorrow I will go see if it still has the fuel tanks on it.

Adam j · 03-13-2018, 10:25 PM

Quote:

Originally Posted by andyh1956

The CUCV trucks had a "Fuel Management Center" filter on the firewall w/ fuel heater / water in fuel sensors in it.
I would bet the extra plug is for an in tank gasoline pump. The new senders are prolly universal in nature & use the same one for diesel, just w/ the pump omitted.
Just guessing here though.
I have a '86 one ton diesel frame left from a truck that I had a mini van drive up into the cab with me up behind the barn. Tomorrow I will go see if it still has the fuel tanks on it.

Awesome man thanks I am hope I can use the one with two plugs on top and just leave the water separator one open seeing that I don't have the wire let me know if anyone has done this or if it's ok to do it
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sweetk30 · 03-13-2018, 10:29 PM

Quote:

Originally Posted by andyh1956

The CUCV trucks had a "Fuel Management Center" filter on the firewall w/ fuel heater / water in fuel sensors in it.
I would bet the extra plug is for an in tank gasoline pump. The new senders are prolly universal in nature & use the same one for diesel, just w/ the pump omitted.
Just guessing here though.
.

fuel pump intank senders didnt start till 87 and there designed to hold the pump . good idea tho .

i did always think if converting gas to diesel these would be a great idea for the lift pump .

andyh1956 · 03-14-2018, 11:43 AM

Reason I said that is this:
My neighbor called one day & said he installed a new fuel pump on his diesel dodge & it wouldn't pump fuel.
The pump he installed went into the tank but his old pump was still on his engine mounted to his fuel filter! WTF???
So I got to looking & sure nuff was a wiring harness on the truck to the pump / sender but the old unit was just a sender. Again, WTF???
Got to looking more & there was OEM wiring to the sender for a pump & pump wiring left new pump / sender & made it's way forward to just behind driver inner fender to plug there but no wiring from that plug forward. I had to use the old pump wiring to trigger a relay to provide voltage to the forward plug back t new in tank pump.
then had to remove old pump from filter canister, drill & tap pipe thread & install a hose barb to hook fuel line to filter.
Voila!

Cummins don't service the filter mounted electric pump anymore so this is how you get it done now.
Whoda thought all that had to happen just to change a transfer pump?
After seeing this it wouldn't sprise me none if they don't make but three sender / pump units for all trucks out there.

Adam j · 03-14-2018, 03:26 PM

Quote:

Originally Posted by andyh1956

Reason I said that is this:
My neighbor called one day & said he installed a new fuel pump on his diesel dodge & it wouldn't pump fuel.
The pump he installed went into the tank but his old pump was still on his engine mounted to his fuel filter! WTF???
So I got to looking & sure nuff was a wiring harness on the truck to the pump / sender but the old unit was just a sender. Again, WTF???
Got to looking more & there was OEM wiring to the sender for a pump & pump wiring left new pump / sender & made it's way forward to just behind driver inner fender to plug there but no wiring from that plug forward. I had to use the old pump wiring to trigger a relay to provide voltage to the forward plug back t new in tank pump.
then had to remove old pump from filter canister, drill & tap pipe thread & install a hose barb to hook fuel line to filter.
Voila!

Cummins don't service the filter mounted electric pump anymore so this is how you get it done now.
Whoda thought all that had to happen just to change a transfer pump?
After seeing this it wouldn't sprise me none if they don't make but three sender / pump units for all trucks out there.

I know the fuel pump is on the motor I was just wondering if I can use the sending unit with the plug for the gauge and the plug for the water in fuel sensor and just not worry with plugging anything to that one will that work and thank everyone for your help y'all make this forum awesome
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Adam j · 03-17-2018, 02:09 PM

Quote:

Originally Posted by Adam j

I know the fuel pump is on the motor I was just wondering if I can use the sending unit with the plug for the gauge and the plug for the water in fuel sensor and just not worry with plugging anything to that one will that work and thank everyone for your help y'all make this forum awesome
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Ok we got the truck running again and it still doing the same thing it will run good for awhile then it loses power and idles rough and shut off and I can crank it right back and it runs fine and idles good for awhile and goes back to no power again please help we can't keep throwing money at this thing
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**hatzie** · 03-17-2018, 09:43 PM

How old is the fuel filter?

Adam j · 03-18-2018, 12:03 AM

My dad had been using this truck as his everyday driver for a year and it has new fuel in it now we replaced the tank and sending unit and fuel filter and nothing has changed plus the fuel pump is new
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**hatzie** · 03-18-2018, 11:38 AM

Is it surging when the power drops off?

Adam j · 03-18-2018, 12:34 PM

No it's just dies no jumping or nothing like that
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Adam j · 03-18-2018, 04:51 PM

Anyone have any ideas it's still losing power and it seems to be worse when it's hot
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wildwilly4x4 · 03-19-2018, 12:32 AM

check fuel return lines. blow through from injection pump outlet with air back to tank. also check to see if the fuel return fitting in the top of the injection pump is clogging up. there's a glass check ball inside that fitting that can trap junk in there

wildwilly4x4 · 03-19-2018, 12:34 AM

back pressure on the fuel return is actually what kills a 6.2 truck when you shut them off. seen the return hose and that outlet fitting plugged more than once in my fleet of trucks.

Adam j · 03-19-2018, 10:37 AM

Thanks guys I will give it a try and see if tha works
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andyh1956 · 03-20-2018, 11:24 PM

I think it's time to bottle feed the engine & see if it runs any different.

03-12-2018, 08:48 PM	#1
Adam j Registered User Join Date: Apr 2012 Location: Lexington south Carolina Posts: 98	6.2 fuel sending unit problems I'm changing the sending unit on my 6.2 and can't find one like it it has 3 outlets and one plug for the gauge and a exterior ground and two of the outlets go into the tank are long and one is short I can't find another like it anywhere it is a old military truck so who knows what it's from and when I look at the one it recommends it has two plugs and the ground is internal please help thanks Posted via Mobile Device

03-12-2018, 10:16 PM	#2
andyh1956 Registered User Join Date: Mar 2010 Location: thomastown mississippi Posts: 1,261	Re: 6.2 fuel sending unit problems Try a Spectra FG05K for driver side or FG05L for pass side. For surplus try Hillbilly Wizard or Ted's Trucks & Stuff. These are for M1008 but may be the same for M1009.

03-13-2018, 03:19 PM	#5
andyh1956 Registered User Join Date: Mar 2010 Location: thomastown mississippi Posts: 1,261	Re: 6.2 fuel sending unit problems When you say two plugs that's electrical plugs correct? Will your wiring harness plug into one of the plugs or do the wires need to be "Divided" between the plugs? You have an M1008 or M1009 or is your tank just from a CUCV?

03-13-2018, 05:35 PM	#6
sweetk30 Registered User Join Date: May 2012 Location: horseheads,ny rust belt Posts: 2,794	Re: 6.2 fuel sending unit problems post up some pics of what ya got . see if I can match it. I have 2 tanks with senders from a diesel truck I parted . looked up for 1985 k30 6.2 diesel . verified 1984 - 1985 - 1986 the vintage of almost all military trucks of this style take the same sender listed . unless military did a weird custom thing . driver side 3 port https://www.rockauto.com/en/moreinfo...053065&jsn=459 pass side 3 port https://www.rockauto.com/en/moreinfo...053065&jsn=458 these what you looking for ? 1 plug/pin is sender feed . the other is water in fuel ? if I recall. short is tank vent / 5/16 is return line / 3/8 is fuel supply . ground is flat spade on 1 of the lock tabs in the pic . __________________ 77-k30lb BIG truck build . 87-k30lb budget beater build . 85-k30lb the plow machine build . 85-c10sb summer fun toy . ----------------------------- HOLLEY SNIPER efi = worst case of p.i.t.a i ever had . EDELBROCK pro flo 4 = best deal going so far . love my setup works great. Last edited by sweetk30; 03-13-2018 at 05:48 PM.

03-13-2018, 05:52 PM	#8
sweetk30 Registered User Join Date: May 2012 Location: horseheads,ny rust belt Posts: 2,794	Re: 6.2 fuel sending unit problems military might have NOT run water in fuel then so no need for 2nd wire to be used . all these gm senders were external ground also . unless you find one like you got then just run a reg one like I posted up . or go try finding some info over on www.steelsoldiers.com . free site but tread light . make sure you look and post in the correct place . __________________ 77-k30lb BIG truck build . 87-k30lb budget beater build . 85-k30lb the plow machine build . 85-c10sb summer fun toy . ----------------------------- HOLLEY SNIPER efi = worst case of p.i.t.a i ever had . EDELBROCK pro flo 4 = best deal going so far . love my setup works great.

03-13-2018, 05:47 PM	#7
Adam j Registered User Join Date: Apr 2012 Location: Lexington south Carolina Posts: 98	It is a m1008 and the sending unit looks like the ones from rock auto but the ground is just on the outside and the top only has one spot for the wire for the gauge to plug in the rock auto one has two Posted via Mobile Device

03-13-2018, 09:36 PM	#10
sweetk30 Registered User Join Date: May 2012 Location: horseheads,ny rust belt Posts: 2,794	Re: 6.2 fuel sending unit problems should be a separate thingy it hooks to for water in fuel light . must not come on new senders . __________________ 77-k30lb BIG truck build . 87-k30lb budget beater build . 85-k30lb the plow machine build . 85-c10sb summer fun toy . ----------------------------- HOLLEY SNIPER efi = worst case of p.i.t.a i ever had . EDELBROCK pro flo 4 = best deal going so far . love my setup works great.

03-13-2018, 10:19 PM	#11
andyh1956 Registered User Join Date: Mar 2010 Location: thomastown mississippi Posts: 1,261	Re: 6.2 fuel sending unit problems The CUCV trucks had a "Fuel Management Center" filter on the firewall w/ fuel heater / water in fuel sensors in it. I would bet the extra plug is for an in tank gasoline pump. The new senders are prolly universal in nature & use the same one for diesel, just w/ the pump omitted. Just guessing here though. I have a '86 one ton diesel frame left from a truck that I had a mini van drive up into the cab with me up behind the barn. Tomorrow I will go see if it still has the fuel tanks on it.

03-14-2018, 11:43 AM	#14
andyh1956 Registered User Join Date: Mar 2010 Location: thomastown mississippi Posts: 1,261	Re: 6.2 fuel sending unit problems Reason I said that is this: My neighbor called one day & said he installed a new fuel pump on his diesel dodge & it wouldn't pump fuel. The pump he installed went into the tank but his old pump was still on his engine mounted to his fuel filter! WTF??? So I got to looking & sure nuff was a wiring harness on the truck to the pump / sender but the old unit was just a sender. Again, WTF??? Got to looking more & there was OEM wiring to the sender for a pump & pump wiring left new pump / sender & made it's way forward to just behind driver inner fender to plug there but no wiring from that plug forward. I had to use the old pump wiring to trigger a relay to provide voltage to the forward plug back t new in tank pump. then had to remove old pump from filter canister, drill & tap pipe thread & install a hose barb to hook fuel line to filter. Voila! Cummins don't service the filter mounted electric pump anymore so this is how you get it done now. Whoda thought all that had to happen just to change a transfer pump? After seeing this it wouldn't sprise me none if they don't make but three sender / pump units for all trucks out there.

03-17-2018, 09:43 PM	#17
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: 6.2 fuel sending unit problems How old is the fuel filter? __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

03-18-2018, 12:03 AM	#18
Adam j Registered User Join Date: Apr 2012 Location: Lexington south Carolina Posts: 98	My dad had been using this truck as his everyday driver for a year and it has new fuel in it now we replaced the tank and sending unit and fuel filter and nothing has changed plus the fuel pump is new Posted via Mobile Device

03-18-2018, 11:38 AM	#19
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: 6.2 fuel sending unit problems Is it surging when the power drops off? __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

03-18-2018, 12:34 PM	#20
Adam j Registered User Join Date: Apr 2012 Location: Lexington south Carolina Posts: 98	No it's just dies no jumping or nothing like that Posted via Mobile Device

03-18-2018, 04:51 PM	#21
Adam j Registered User Join Date: Apr 2012 Location: Lexington south Carolina Posts: 98	Anyone have any ideas it's still losing power and it seems to be worse when it's hot Posted via Mobile Device

03-19-2018, 12:32 AM	#22
wildwilly4x4 Registered User Join Date: Aug 2009 Location: Sunray,TX Posts: 251	Re: 6.2 fuel sending unit problems check fuel return lines. blow through from injection pump outlet with air back to tank. also check to see if the fuel return fitting in the top of the injection pump is clogging up. there's a glass check ball inside that fitting that can trap junk in there



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03-19-2018, 12:34 AM	#23
wildwilly4x4 Registered User Join Date: Aug 2009 Location: Sunray,TX Posts: 251	Re: 6.2 fuel sending unit problems back pressure on the fuel return is actually what kills a 6.2 truck when you shut them off. seen the return hose and that outlet fitting plugged more than once in my fleet of trucks.

03-19-2018, 10:37 AM	#24
Adam j Registered User Join Date: Apr 2012 Location: Lexington south Carolina Posts: 98	Thanks guys I will give it a try and see if tha works Posted via Mobile Device

03-20-2018, 11:24 PM	#25
andyh1956 Registered User Join Date: Mar 2010 Location: thomastown mississippi Posts: 1,261	Re: 6.2 fuel sending unit problems I think it's time to bottle feed the engine & see if it runs any different.

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