Help! Stranded with Fuel Issues!

[ModernMuseum]

Hopefully you guys can help, because I am at a loss and my car is at a buddy's house.

Engine: cammed LS3
Fuel Pump: Walbro 255
Regulator/filter: Corvette regular that everyone uses (not sure of model number)
Tank: DSE (Mechanical fuel pump style) tank

https://static1.pt-content.com/images/pt/2012/01/6139749075_4e9e98b999_z-1.jpg

The car was dyno'd on a previous pump: a Walbro 255 from ebay and I got about 3 hours out of it before it failed. Once I got the car home from the dyno shop, within a day or so it started sputting on take-off. Eventually it got to where I could't even drive around the neighborhood and wouldn't speed up past idle. Due to the ridiculously loud whine of the Walbro, I thought it might be a bad pump.

I replaced the pump and it still whined a little, though the problem seemed to be fixed except for a very slight hesitation on take-off. Yesterday was the first day that the car was legal, so I took it out for a spin. Today, about 3 total combined hours or so after running the new pump (hell, maybe even only 2 hours), the car started sputtering again and now I can barely putter down the street. It falls on its face upon take-off and I'm stranded in town.

The pump/regulator setup that I'm using (below) may be a little obscure, but quite a few people have told me that it should work without issues. Basically, instead of sending the return line back to the tank, I am sending it back to the pump suction. I guess I could order a new pump just to get the car home, but I'd like to stop throwing money at the problem, though I'm sure I'll need a new pump anyway.

I put a mechanical fuel pressure gauge on the rail and it is reading about 55 pounds constantly. I am not sure what the pressure was right after I put the pump on; could have been more or could have been the same - not sure. What pressure are these things supposed to run? Is it a problem with the Walbro, perhaps the regulator is bad, or is there a problem with my plumbing? I would have run a return back to the tank, but there is no port for a return on the DSE tank (mechanical fuel pump version).

Help, I'm stranded!

[jprewitt]

It is really hard to tell from the picture, but it looks like you have your line going out of the pump then to the fuel filter with a tee for the return line that then just goes back to the pump? If that is the case it doesn't surprise me that it doesn't work. What you need is a line going from the pump to the filter then to your fuel railed then to a regulator and then finally back to tee in front of your pump. With the way you have it ran now the path of least resistance for the fuel is the loop you have between you tees. I'm actually surprised that it works at all.

[Bryce]

I agree with jprewitt. A return system needs to have a second regulator. My system uses a 7psi regulator at the carb and a regulator set at 13psi right after the pump that is a return style and sends fuel back to the tank.

[FatfreeGTO]

Well his filter is the regulator so no additional regulator is needed.

About your pump, there a tons of knock off walbro pumps on ebay. Make sure you are buying from a well respected business who wouldn't risk their reputation with a cheap knock off. Pretty much if you payed $80 or so for your pump its a fake. The real ones sell for just over a $100 or so.

You can't simply "T" that return line back in before the pump that has to go to the tank. I would say the main reason being that heat is what kills these pumps, and after your fuel is pumped through the Walbro it is being heated up and then going back through the pump hotter and it just keeps getting hotter. People usually try to locate their return line away from the pickup tube that is in the tank to allow the pickup to only suck cold fuel.

Also you need to install a pre filter before your fuel pump. 100 micron would work well, that is what I am running. Check out RobbMc (http://www.robbmcperformance.com/products/filters.html) for a filter.

I have the same exact setup as you running my engine without issue, only difference is what is mentioned above and I have my factory tank still.

Good luck.

[FatfreeGTO]

Oh and 58 psi is what the Vette regulator is supposed to supply the fuel rails with for pressure. If your tank has a "vent" tube on the filler neck you can try to use that for a very temporary solution. Problem is those vent tubes are usually to small 5/16" minimum is needed to allow for proper flow. I would recommend emptying the tank, removing it and hopefully you can find a local shop who will wash it out and attach a proper return barb/line/fitting into the tank for you.

[camcojb]

I agree, you cannot run your bypass there. It needs to go back to the tank. They make a kit if your rubber hose for the gas tank is long enough.

54117

[FatfreeGTO]

That is a neat part you found there Jody :twothumbs: I like it!

[neki67]

I use the factory tank with the same set up you're running except the return is going back into the tank (through the original outlet). I'm using it for 5000 miles now. This summer it brought me and my GF from the Netherlands to Austria (via the Nürburgring!) and back for a total of 2000 miles w.o. any issues!

I have to agree with what was mentioned before; the fuel is getting way too hot and killing the pump.

[ModernMuseum]

Thanks for the comments, guys. I got similar feedback from ls1tech as well, basically stating that they thought the issue was with routing the flow back to the pump suction.

I ordered a fitting from JEGS to pump the return back into the tank, so hopefully that will solve the issue. I will know in a few days and will report back then.

I assume the pressure regulator is working fine based on the comments above, so that is a relief.

[ModernMuseum]

I have ran the car for about 2-3 hours total, so I guess the new setup is going to work. There's still a slight hesitation at take-off, but I attribute it to the cam I guess.

Lifting the tank back into the car solo style was fun as always. I'm getting pretty good at it now though :lol:


https://static1.pt-content.com/images/pt/2012/01/6748730379_8ca16e19a8_z-1.jpg

https://static1.pt-content.com/images/pt/2012/01/6748760289_96ac6a3f14_z-1.jpg


I'm not really sure why these pumps failed, or what failed internally, I just know that they failed. What's funny is that they will still run and produce enough flow/pressure to idle, but once you give it some gas and put a load on the motor, the pump gives out and can't make up the pressure drop.

Also, I should add that the pump doesn't have the ridiculously loud whine that it had before. I checked the exterior of all of the pumps and they all appeared to be identical and authentic. They all the the Walbro symbol on them with identical engravings, so I assume they were all legit Walbro pumps.

Oh, well. It works now, so on to the next set of gremlins.

[FatfreeGTO]

Glad to hear you got it taken car of. When you were on the dyno was it just for numbers or did you get a tune done? Maybe some of that hesitation could be taken car of with tuning.

[ModernMuseum]

They did tune it, but now I'm thinking that I need to take the car back since they tuned it on the faulty pump setup.

I need to take it back anyway because one of the settings is set too low. I don't remember the acronym for it, but it is the function that turns your fuel back on (your fuel supposedly partially cuts off when you let off the gas) when it reaches a certain RPM. The setting is set too low and it dies every now and then.

The first dyno session is $500ish and every subsequent session is only $75.

[FatfreeGTO]

Interesting... Its good that the retune is only $75. I paid $450 for my time on the dyno picked up 80lb tq and 50 hp right in the midrange which was worth it. Only thing I need to have redone is after a cold startup the car kind of hiccups for the first minute of driving. I'm hoping they have a similar small fee for adjustments.

I checked out your build thread car is looking sweet!!

[ModernMuseum]

Thanks man. I hope to have some rolling shots up soon. Stay tuned...