TBI fuel pump - Walbro install

[skysurfer]

After searching the net and not finding anything that covers Walbros and the square bodies, I thought I would post up a few pics. The reason for this upgrade is the stock pump can supply about 15psi and support engines up to around 275 horsepower, beyond that you'll have to go with something else. My future engine plans should put me in the low 300's so the Walbro 190 can easily provide the necessary fuel. Above 350 hp a Walbro 255 would be a better choice.

Dealing with a Suburban here, which means a rear-mounted tank and the typical things that prevent you from easy access. In this case that means a hitch and skid pan.

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I tried to just remove the hitch first but realized it would be easier to just take the bumper off as well.

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Then the hitch came off...

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but not without a fight. There's always that one bolt that's determined to mess up your day. If you don't have one of these in your toolbox, it should be the next thing you buy. The Makita GEO600 turns 25,000 rpm's and buzzed through this grade 8 bolt in twenty seconds.

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Next was the skid pan, held on by six bolts. Note one of the tank strap bolts to the left.

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With the pan bolts removed, I lowered the plate with a floor jack, but it's not really that heavy. It was reinstalled later without the jack.

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Next was the filler neck hose and the overfill return line next to it. I removed the rubber section of return line but the fill section has to come down with the tank.

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You'll also need to remove the bolt that holds the pressure and return lines to the frame so the tank can be lowered. This is on top of the passenger side frame rail located even with the front edge of the tank and can be accessed through the wheel well.

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[skysurfer]

Next, support the tank and remove the straps that hold it. I had about five gallons in it and wouldn't try this with any more. A helper would have been nice at this point.

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As I started to lower the tank it began to tilt towards the driver's side because the filler neck is over the frame on the passenger side. What followed was a balancing act with jack stands and careful lowering of the tank until the filler hose could be pushed aside.


With the tank lowered about a foot I could reach in and undo the supply, return, and fuel evap hoses.

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After that the tank was lowered the rest of the way. I was fortunate that someone had spliced in a section to the wire in the foreground so it was long enough to remain attached, and the two wires in the back are long enough in stock form so the electrical was left hooked up.

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At this point I spent lots of time removing as much dirt as possible from the neck area. A wire brush, vaccuum, and air hose are good to have. A hammer and brass drift were used to rotate the locking ring about 180 degrees (light colored ring in photo) until the release points lined up.

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With the locking ring loose the pump can be removed from the tank. The float (lower right) sits under the lip towards the back so you have to first pull the filter sock up through the neck then tilt the whole assy towards the rear of the vehicle so the float can come out.

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In the pic below and looking at the underside of the filler neck, the top, shorter Z shaped pipe is the supply connected to the pump. The 3" long tube below that is the overfill return. Just behind that is the longer Z shaped tube that is the return line from the throttle body which carries unused fuel back to the tank. The return tube also has a bracket attached to the bottom of it that the pump sits on.

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The pump comes with a foam tube around it to help quiet the noise. Don't know how effective it is but the Walbro is the same diameter so I reused it. I also reused the two black hose clamps because they looked better than the ones that came with the new pump.

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[skysurfer]

Here's what I got with the install kit. From what I've seen online this is a kit for Mustangs. I didn't need the rubber hose, clamps, or gray gasket ring.

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Different terminals at the pump.

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After removing the old pump, place the new rubber gasket on the Walbro and place on the return tube bracket. Press the new filter sock on then attach the rubber line to the pump outlet.

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Cut the gray and black wires and splice in the new leads connected to the pump.

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Then reassemble everything in reverse order. Turn the ignition key on for a few seconds then off again. Repeat a few times to allow the pump to prime then start the engine. If you did everything right it will start right up and then check for leaks.

I was concerned that the new pump might provide more fuel than could be returned through the stock return lines which would cause an increase in fuel pressure, but checking the gauge on my adjustable regulator showed no increase so everything went as planned.


Aeromotive 13301 was installed at an earlier time and hidden on the frame rail in order to pass smog inspections. Fuel pressure adjustments with this setup can be made in less than thirty seconds.

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[bucket]

With that regulator setup, what are you using for a regulator on the TB?

Also, after having to replace the pump on my Burb a couple times, I decided to make an access door in the rear floor. Replacing the pump is now a 20 minute job, so it can easily be done on the side of the road. A good fuel pump is in with the other parts in my roadside repair kit.

 

[skysurfer]

I left the stock regulator in place. There's no need to do anything with it since the system works on restriction to increase pressure. The stock regulator senses the increase caused by the Aeromotive downstream and just goes wide open in an attempt to reduce pressure. I installed this a couple years ago and it works perfectly.

I thought about making a hatch for future access but I don't anticipate doing this again for a long time. The pump I pulled out was in there for ten years and still working. I never drive this rig far from home and my AAA coverage provides tow up to 100 miles so I can always get home.

 

[89Suburban]

God damn, outstanding write up!

By the way, yes, it does make me sick how clean the underside of that trucks is.

Also if anybody has a good pic of the interior home made cut out location for accessing the fuel pump from inside, plead post to help others with cutting the right spot.