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1987 760 Walbro 255 In-Tank Fuel Pump Upgrade

Help, Advice, Owners' Discussion and DIY Tutorials on all Volvo's "mid era" rear wheel drive Volvos.

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Cleanyo
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Joined: Tue May 28, 2019 9:41 am
Year and Model: 1987 760GLE
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Cleanyo

1987 760 Walbro 255 In-Tank Fuel Pump Upgrade

Post by Cleanyo » Tue May 28, 2019 9:51 am

Hey everyone! I'm new so let me know if this should be posted somewhere else!

TIME: 2-4 Hours (rough rough estimate)

I own a 1987 760 GLE (V6), and I wanted to add a bit to the community as I have recently upgraded the in-tank lift pump from the stock 13 psi one to a Walbro 255 60psi pump.

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This is the same pump I have on my LS swapped '82 Camaro, so I figured it would be a good replacement for the old pump in the 760 as the old one was going out anyway, and I plan on putting a turbo on this brick in the future. Only very minor adjustments were necessary.

Removing the old pump looked daunting at first until I found out that there is a hatch designed exactly for this! Thanks Volvo! The hatch..or plate, is located in the trunk, so you might have to get inside of your trunk with the toold necessary for the job.

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Pull the sending unit by disconnecting hoses and wired, then turning the large threaded ring around the whole thing with a soft chisel and hammer combo, slowly tapping away until you can turn it by hand.

My fuel pump seemed like it had been replaced, as the wires were, unfortunately, butt connected (very very poorly, almost all wires fell out with little pulling), so im not sure if there is usually a connector there. In my case, I cut the wires, planning on using solder butt connectors to close it up.

Once the sending unit is out, disconnect the old lift pump, and take the orange plastic sleeve that was around it off of the sending unit as well. The Walbro pump is a bit girthier so it required me to simply cut the plastic sleeve so it could open up a bit, then securing it back with zip ties. In my photos you can see that I soldered the new connector directly to the old wires, but only because they were corroded all the way down. If your wires are alright, the Walbro pump kit comes with an adaptor harness.

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Connect everything up, zip tie the pump acouple of times, and add the filter onto the bottom by pusing really hard, and voilĂ ! You have a turbo ready pump. Put everything back in the car and really make sure your hose clamps are on tight cause the pressure difference is substantial.

I sprung a few leaks, but only at hose clamp areas, only requiring me to tighten them all up. The pump works fine currently, even with the main pump in front of it. I plan on just takiing that out and replacing it with a soft line this weekend.

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Let me know if you have any questions!

Also thanks to Bad Company Inc in Toano, VA for letting me use their shop and for their help.
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lummert
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lummert

Re: 1987 760 Walbro 255 In-Tank Fuel Pump Upgrade

Post by lummert » Wed May 29, 2019 9:35 am

Did you use high pressure fuel injection hoses to connect to the main pump? 1/2" (12.7 mm) standard fuel hose is rated at 25 psi. With both high pressure pumps running the pressure between the pumps is about 7 psi, the main pump can out-pump the in-tank pump, if the main pump were to quit the pressure increase on standard 12 mm fuel hose could cause the hose to burst. I had thought of using a pressure relief valve to relieve excess pressure to the return hose. Then I decided to use a low pressure, high volume in-tank pump from a Chevy S-10 with throttle body injection. Stock type main pump still in place on 1988 Volvo 760 Turbo Wagon.


1988 Volvo 760 Turbo Wagon

Cleanyo
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Cleanyo

Re: 1987 760 Walbro 255 In-Tank Fuel Pump Upgrade

Post by Cleanyo » Fri May 31, 2019 10:28 am

lummert wrote: ↑
Wed May 29, 2019 9:35 am
Did you use high pressure fuel injection hoses to connect to the main pump? 1/2" (12.7 mm) standard fuel hose is rated at 25 psi. With both high pressure pumps running the pressure between the pumps is about 7 psi, the main pump can out-pump the in-tank pump, if the main pump were to quit the pressure increase on standard 12 mm fuel hose could cause the hose to burst. I had thought of using a pressure relief valve to relieve excess pressure to the return hose. Then I decided to use a low pressure, high volume in-tank pump from a Chevy S-10 with throttle body injection. Stock type main pump still in place on 1988 Volvo 760 Turbo Wagon.
Yes! I am in the process of changing over to high pressure hose :). Also you just helped me order the right size hose haha thank you



tardcart
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tardcart

Re: 1987 760 Walbro 255 In-Tank Fuel Pump Upgrade

Post by tardcart » Fri May 31, 2019 4:15 pm

the last picture looks like your holding a stick of dynamite. don't take that to the bank with you. It could be it is one- with 60 pounds at the tank. even fuel injection hose is only 45 rated. there is a reason the main pump has metal banjo fittings and hard plastic line. also the return line will be violently active trying to return 15 lbs of pressure off the damper back to the tank. The chevy throttle body injection TBI pump as mentioned above in all cars and trucks 87-97 is cheap and same size and 6 psi. Do not use any rubber hose in the tank except gas submersible hose which is hard to find SAE 30R10. Napa can get it but you will have to look up their number for the gates line. The chevy pump comes with a piece.



jimmy57
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jimmy57

Re: 1987 760 Walbro 255 In-Tank Fuel Pump Upgrade

Post by jimmy57 » Fri May 31, 2019 5:30 pm

What is huge overcapacity of pumps supposed to help or fix on a B280F? That system runs about 35 psi at WOT(250 kPa above intake manifold pressure) and you may be oversupplying the flow rate of the fuel pressure regulator. Pressure is made due to the pump volume being great enough to make the 35 psi and being capable of at least 0.5 gallons per minute or so at that pressure. If you do turbocharger or other serious performance mods then you need to up the pump capacities of at least the main pump. All dependent on how crazy you get with power addition. The Bosch pump under the car has a great history and its check valve has been a long lasting part and is serviced separately (well, maybe no one sells it any more...) from the whole pump. The in-tank pump on that car was chosen for its ability to push about a gallon per minute at low pressure and purge vapor bubbles out of that fuel supply. The main pump stinks at dealing with entrained vapor but is great at making pressure at a more than adequate volume. A B280F has a hot wire MAF. A new Bosch MAF would be the best perf mod for that car as hot wire mafs get dirty sensing wire from the first KG of air that passes through it. With time the signal goes down and even though Lambda Sond (O2 sensor) correction makes up for it off idle and the correction screw on MAF fixes, within its capability, the idle fuel trim, a new base signal that is more accurate will wake up a sluggish LH injection engine.



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