Walbro install
10-14-2006, 08:15 PM
#1
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Walbro install
This afternoon I started installing my secondary fuel system. I will be using a Walbro 391 with a bypass after the filter to try to maintain 15 psi to the VE at all times. The Walbro 391 is a high volume and high pressure gerotor pump typically used in EFI applications. The mechanical lift pump will stay in place and functioning for the time being. Here's an overview of how the system will work. I added a new pickup in the fuel tank to feed the Walbro. The Walbro will pump fuel into the stock filter head though a banjo bolt tapped for 1/4" NPT. The hard line from the filter head to the VE pump is being replaced with AN fittings and 3/8" fuel hose. The bypass return line is teed into this hose, this way the bypass valve reads post-filter pressure. From the bypass valve the excess fuel is dumped into the tank vent line.
I got the specialty fittings, the pump, the pickup, and the bypass valve from Glacier Diesel Power. The standard fittings and miscellaneous stuff came from McMaster-Carr.
Today's adventures: First, I had to drop the tank. In order to get enough working clearance under the truck and keep it level, I jacked up the truck and set it on chunks of 4x4 lumber - 4wd guys will not need to do that. Then I disconnected the fill and vent hoses. I used a floor jack to support the weight while I removed the bolts from the tank straps. Then I lowered the tank a couple inches to get room to disconnect the feed and return lines and the fuel gauge plug. After those were off, I lowered the tank the rest of the way. The fill pipe has to be rotated as you drop the tank so it clears the frame. Once the tank was all the way down, I unscrewed the lock ring and tried to lift out the stock sending unit/pickup assembly. Unfortunately, the tank was still too high, so I had to drop it on the ground. After I got the pickup assembly out, I realized that it telescopes - so I did not need to set the tank on the ground.
If I had realized that I could collapse the pickup assembly, I would have saved a lot of time I spent wrestling the tank back up on the jack.
Now that the tank was on the ground, it was time to install the pickup.
I drilled a 1" hole in the top of the tank far enough away to clear the lock ring, and in a location where I could access the fitting with the tank installed. A spade bit drills though the plastic tank just fine, and I was able to fish the disc that it cut out the tank. The pickup tube is long enough that it lays on the bottom of the tank for about 4 inches, I installed it facing rearward. Then it was time to put the factory pickup back in and put the tank back up. THis was not a lot of fun, since I didn't use as much fuel this week as I'd hoped. There were probably around 12 gallons of fuel in the tank.
To put it back up I had to use a crowbar to lift the front end off the ground enough to toss a block of wood under it. The front end was much lighter once the fuel ran to the rear, so I was able to shove a car ramp under it. Then I used the crowbar again to get the jack under the rear of the tank. I jacked the tank most of the way up then reconnected the factory fuel fittings and the gauge sender. Then I jacked the back of the tank into place, making sure to rotate the fill tube back to clear the bed and frame. I installed the rear strap bolt loosely, and moved the jack to the front to install the front strap bolt. All this was easy to type, but it involved about an hour of struggling with the tank. 
If you have a choice, run until you are almost out of fuel. Here's a pic of the pickup after I put the tank back up. 
While I was reconnecting the fill and vent hoses, I installed the return tee.
Then it was time to mount the pump. I chose a spot on the frame rail under the cab, marked my holes and drilled for 1/4" bolts. The pump mounts in a foam sleeve using two Adel clamps.
Here's the pump mounted, wired, and plumbed. The purple crap is battery terminal spray to try to keep the connections from corroding.
As of right now I am done under the truck except for securing all the new wires and hoses. Tomorrow it will be time to do the underhood plumbing and wire a relay for the pump. Right now I'm beat, and I still smell faintly of diesel fuel even after a shower.
I got the specialty fittings, the pump, the pickup, and the bypass valve from Glacier Diesel Power. The standard fittings and miscellaneous stuff came from McMaster-Carr.
Today's adventures: First, I had to drop the tank. In order to get enough working clearance under the truck and keep it level, I jacked up the truck and set it on chunks of 4x4 lumber - 4wd guys will not need to do that. Then I disconnected the fill and vent hoses. I used a floor jack to support the weight while I removed the bolts from the tank straps. Then I lowered the tank a couple inches to get room to disconnect the feed and return lines and the fuel gauge plug. After those were off, I lowered the tank the rest of the way. The fill pipe has to be rotated as you drop the tank so it clears the frame. Once the tank was all the way down, I unscrewed the lock ring and tried to lift out the stock sending unit/pickup assembly. Unfortunately, the tank was still too high, so I had to drop it on the ground. After I got the pickup assembly out, I realized that it telescopes - so I did not need to set the tank on the ground.
If I had realized that I could collapse the pickup assembly, I would have saved a lot of time I spent wrestling the tank back up on the jack.Now that the tank was on the ground, it was time to install the pickup.
I drilled a 1" hole in the top of the tank far enough away to clear the lock ring, and in a location where I could access the fitting with the tank installed. A spade bit drills though the plastic tank just fine, and I was able to fish the disc that it cut out the tank. The pickup tube is long enough that it lays on the bottom of the tank for about 4 inches, I installed it facing rearward. Then it was time to put the factory pickup back in and put the tank back up. THis was not a lot of fun, since I didn't use as much fuel this week as I'd hoped. There were probably around 12 gallons of fuel in the tank.
To put it back up I had to use a crowbar to lift the front end off the ground enough to toss a block of wood under it. The front end was much lighter once the fuel ran to the rear, so I was able to shove a car ramp under it. Then I used the crowbar again to get the jack under the rear of the tank. I jacked the tank most of the way up then reconnected the factory fuel fittings and the gauge sender. Then I jacked the back of the tank into place, making sure to rotate the fill tube back to clear the bed and frame. I installed the rear strap bolt loosely, and moved the jack to the front to install the front strap bolt. All this was easy to type, but it involved about an hour of struggling with the tank. If you have a choice, run until you are almost out of fuel. Here's a pic of the pickup after I put the tank back up. While I was reconnecting the fill and vent hoses, I installed the return tee.
Then it was time to mount the pump. I chose a spot on the frame rail under the cab, marked my holes and drilled for 1/4" bolts. The pump mounts in a foam sleeve using two Adel clamps.
Here's the pump mounted, wired, and plumbed. The purple crap is battery terminal spray to try to keep the connections from corroding.
As of right now I am done under the truck except for securing all the new wires and hoses. Tomorrow it will be time to do the underhood plumbing and wire a relay for the pump. Right now I'm beat, and I still smell faintly of diesel fuel even after a shower.
10-14-2006, 08:20 PM
#3
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Forgot something important - there's no screen on the new pickup, so a suction strainer is needed before the pump. It looks like a generic gasser fuel filter, but the element is a 0.020" screen. Small enough to stop the big chunks, but not so small as to restrict flow. In this one the arrow points to the inlet. 
10-14-2006, 08:32 PM
#4
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Dave looks like you have been busy!
When you had you tank module out, did you take a good look at you suction lines and your return lines to make sure the tank module wasn't rubbing on them. I now, it's a little bit late now if you didn't!
When you had you tank module out, did you take a good look at you suction lines and your return lines to make sure the tank module wasn't rubbing on them. I now, it's a little bit late now if you didn't!
10-14-2006, 11:03 PM
#6
Registered User
Looks like a good job Dave, I'll have to check it out sometime. Electric lift pumps are not for me yet, too 24 valvish. Maybe I'll put a walbro on the 24 valve one day.
10-15-2006, 06:33 AM
#7
Adminstrator-ess
Thread Starter
I'm no fan of electric fuel pumps either, that's why I'm keeping the stock fuel system intact. 
Once I get this system up and running I want to get the rebuild kit for the 2nd gen piston pump and see if the stiffer pressure spring can shove enough fuel through the filter to keep the pressure up under load. If it works I'll hook it up to the new pickup and sell the Walbro to an overvalver.
Once I get this system up and running I want to get the rebuild kit for the 2nd gen piston pump and see if the stiffer pressure spring can shove enough fuel through the filter to keep the pressure up under load. If it works I'll hook it up to the new pickup and sell the Walbro to an overvalver.
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10-15-2006, 05:01 PM
#9
Registered User
Best of luck, Dave Sounds like a well thought out project, as usual. I certainly hope the results prove that it was worth your time--those of us without 14mm heads on the bench will have something to reach for
greg
Sounds like a well thought out project, as usual. I certainly hope the results prove that it was worth your time--those of us without 14mm heads on the bench will have something to reach forgreg
10-15-2006, 05:09 PM
#10
Adminstrator-ess
Thread Starter
And the fun continues...
This morning I went out at about 11:00 to do what I thought would be two hours work. I actually finished at 4:00. The finished product:
The first order of business was to remove the hard line that goes from the filter head to the VE, I retarded the pump all the way to give more room to remove the line. The fitting was stuck to the line so I wound up having to remove it in two pieces anyway. With the hard line out of the way I installed the Big Line kit from GDP.
This is a bolt-on for any 1st gen, it replaces the banjo bolt and 5/16" line with -6 AN fittings and 3/8" fuel hose. If you want one, order the '98.5 - '02 version. I spliced a tee into the Big Line for the bypass, and installed the gauge port in that line before the bypass valve. I hooked the bypass to the return line.
Then I dropped the filter and replaced it with a longer version, Fleetguard FS1221. The only drawback to this filter is that you lose the WIF sensor. Not a big deal if you drain the filter on a regular basis, but something to be aware of before you make the switch.
Next it was on to the inlet side. The plan was to replace the inlet banjo with a 1/4" NPT tapped banjo bolt from GDP. After about 15 minutes of trying to start the bolt in the hole, it was clear that something was wrong. Turns out the thread pitch is right, but the bolt is about 0.020" bigger in diameter.
Not sure how that happened, since all the AN adapters for the Big Line kit threaded right in. On to plan "B". I was using a 1/8" NPT tapped banjo bolt to feed the pressure gauge on the old setup, so it was down to the basement to drill and tap that sucker for 1/4" NPT. The retapped Geno's banjo bolt threaded right in with no trouble. Once that was done, I installed a 1/4" elbow in the banjo bolt with a hose barb on one leg and a pressure gauge on the other. This is no longer on the truck, but I'll get to that later. With the plumbing complete, I wired a relay to power the pump and the install was complete. I turned the key on and hit the lift pump/valet solenoid switch. Success! The fuel pressure gauge in the cab read 18 psi, the gauge under the hood read 25 psi. At 25 psi, the Walbro pushes 65 GPH. I started the truck and let it idle for a few minutes while I started putting away my tools. After a few minutes, I started looking for leaks - and found one. The reducer bushing for the underhood pressure gauge was leaking. I cranked it down until it bottomed out, but still no joy. OK, on to plan "C".
Off came the elbow, and in its place I put a hose barb. Not too disappointing, since I got to find out what the pressure drop through the filter was before I had to pull the gauge. OK, now everything's tight and there can't be any more trouble, right? Nope, the barb is weeping ever so slightly where it threads into the banjo bolt. 
I've always assembled diesel fuel connections dry because the diesel will eat teflon tape. There is special petroleum safe tape, but most people don't recommend using it because you always lose some inside the pipe. I'm going to have to get some and try it, because I can't make this barb any tighter. The filter will just have to deal with any pieces that fall in. Here are the current connections at the filter head:
So, what were the results? After a shower and some much-needed lunch/dinner, it was time for a test ride. The truck fired up on the mechanical system, but it stumbled a little so I turned on the Walbro. The leak at the banjo/barb connection is obviously letting air in the system. First driving impressions: The fuel pressure gauge is now very boring to watch. Under normal driving conditions it just sits at 18 psi. Once the thermostat opened, it was time for the real test. At full power in 5th gear, fuel pressure is 15 psi. So it works pretty well, but the VE is passing the full flow of the Walbro.
If I had it to do over again, I would buy the Walbro 392. It flows 85 gph at 25 psi. I went with the 391 because I was concerned that the pressure before the filter was going to be too high with the bigger pump. I was expecting a 15 psi drop through the filter with the 391, but with only a 7 psi drop it's obvious that the 392 would have been a better choice. After I get the leak cleared up and the wallet recovers, I'll probably move up to the 392 and sell the 391 to an overvalver.
This morning I went out at about 11:00 to do what I thought would be two hours work. I actually finished at 4:00. The finished product:
The first order of business was to remove the hard line that goes from the filter head to the VE, I retarded the pump all the way to give more room to remove the line. The fitting was stuck to the line so I wound up having to remove it in two pieces anyway. With the hard line out of the way I installed the Big Line kit from GDP.
This is a bolt-on for any 1st gen, it replaces the banjo bolt and 5/16" line with -6 AN fittings and 3/8" fuel hose. If you want one, order the '98.5 - '02 version. I spliced a tee into the Big Line for the bypass, and installed the gauge port in that line before the bypass valve. I hooked the bypass to the return line.
Then I dropped the filter and replaced it with a longer version, Fleetguard FS1221. The only drawback to this filter is that you lose the WIF sensor. Not a big deal if you drain the filter on a regular basis, but something to be aware of before you make the switch.
Next it was on to the inlet side. The plan was to replace the inlet banjo with a 1/4" NPT tapped banjo bolt from GDP. After about 15 minutes of trying to start the bolt in the hole, it was clear that something was wrong. Turns out the thread pitch is right, but the bolt is about 0.020" bigger in diameter.
Not sure how that happened, since all the AN adapters for the Big Line kit threaded right in. On to plan "B". I was using a 1/8" NPT tapped banjo bolt to feed the pressure gauge on the old setup, so it was down to the basement to drill and tap that sucker for 1/4" NPT. The retapped Geno's banjo bolt threaded right in with no trouble. Once that was done, I installed a 1/4" elbow in the banjo bolt with a hose barb on one leg and a pressure gauge on the other. This is no longer on the truck, but I'll get to that later. With the plumbing complete, I wired a relay to power the pump and the install was complete. I turned the key on and hit the lift pump/valet solenoid switch. Success! The fuel pressure gauge in the cab read 18 psi, the gauge under the hood read 25 psi. At 25 psi, the Walbro pushes 65 GPH. I started the truck and let it idle for a few minutes while I started putting away my tools. After a few minutes, I started looking for leaks - and found one. The reducer bushing for the underhood pressure gauge was leaking. I cranked it down until it bottomed out, but still no joy. OK, on to plan "C". Off came the elbow, and in its place I put a hose barb. Not too disappointing, since I got to find out what the pressure drop through the filter was before I had to pull the gauge. OK, now everything's tight and there can't be any more trouble, right?
Nope, the barb is weeping ever so slightly where it threads into the banjo bolt. I've always assembled diesel fuel connections dry because the diesel will eat teflon tape. There is special petroleum safe tape, but most people don't recommend using it because you always lose some inside the pipe. I'm going to have to get some and try it, because I can't make this barb any tighter. The filter will just have to deal with any pieces that fall in. Here are the current connections at the filter head:So, what were the results? After a shower and some much-needed lunch/dinner, it was time for a test ride. The truck fired up on the mechanical system, but it stumbled a little so I turned on the Walbro. The leak at the banjo/barb connection is obviously letting air in the system. First driving impressions: The fuel pressure gauge is now very boring to watch.
Under normal driving conditions it just sits at 18 psi. Once the thermostat opened, it was time for the real test. At full power in 5th gear, fuel pressure is 15 psi. So it works pretty well, but the VE is passing the full flow of the Walbro. If I had it to do over again, I would buy the Walbro 392. It flows 85 gph at 25 psi. I went with the 391 because I was concerned that the pressure before the filter was going to be too high with the bigger pump. I was expecting a 15 psi drop through the filter with the 391, but with only a 7 psi drop it's obvious that the 392 would have been a better choice. After I get the leak cleared up and the wallet recovers, I'll probably move up to the 392 and sell the 391 to an overvalver.
10-15-2006, 05:18 PM
#11
Registered User
Sooo, 15psi into the VE SHOULD mean the pump can maintain internal pressure/timing under full boogie...any thoughts on power above 2200? How about smoke? I can almost feel when the PODs starve the pump and I lose timing right now....
10-15-2006, 10:01 PM
#14
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Where are you regulating/returning at? Before the filter? I would just watch your pressures with those filters elements.
How about just ditching the stock filter/head for the electric side.
Medium flow Racor filters can handle 30psi and drop less than 1 psi across the filter when clean. They can also flow some good numbers from 45-90gph
Some Racor specs
That barrel filter scares me a bit..cold diesel..little cold barrel filter
Den
How about just ditching the stock filter/head for the electric side.
Medium flow Racor filters can handle 30psi and drop less than 1 psi across the filter when clean. They can also flow some good numbers from 45-90gph
Some Racor specs
That barrel filter scares me a bit..cold diesel..little cold barrel filter
Den
10-16-2006, 06:38 AM
#15
Registered User
Where are you regulating/returning at? Before the filter? I would just watch your pressures with those filters elements.
How about just ditching the stock filter/head for the electric side.
Medium flow Racor filters can handle 30psi and drop less than 1 psi across the filter when clean. They can also flow some good numbers from 45-90gph
Some Racor specs
That barrel filter scares me a bit..cold diesel..little cold barrel filter
Den
How about just ditching the stock filter/head for the electric side.
Medium flow Racor filters can handle 30psi and drop less than 1 psi across the filter when clean. They can also flow some good numbers from 45-90gph
Some Racor specs
That barrel filter scares me a bit..cold diesel..little cold barrel filter
Den
