Walbro 255 fuel pump
 

Hello to all. I'm using the Walbro 255 external pump for my LSx fuel delivery needs. Once the engine reaches normal operating temperatures, the Walbro 255 starts to whine loudly. Because of this, I replaced it with a new unit. The second unit runs loudly also. Is this normal? What fuel pumps are you all using? The msd 2555 is a viable option but the 5/16 outlet size has me worried. The Walbro 255 has -6an inlet and outlet size. Thanks for your help.

Re: Walbro 255 fuel pump
 

The 255 is pretty much the most common part. If its whining, there are a couple things that can be at play;

Heat/lack of cooling is a function of flow. The pump needs to have cool gas passing through it, so mounting locations are important. Where is your pump? The higher and further away it is from the pickup, the more suction force the pump needs and strain it puts on it while running dry.

If you have a restriction from a clogged filter, too tight of a micron rating, or just too many filters it can cause similar issues as well (so would a pinched line for that matter).

Also, doublecheck that you have a good hot wire and solid ground. The pumps draw decent amps, but you can put a multimeter on one and see what your drawing. If the internal motor is drawing much higher than whatever they are rated, it means the motor itself is dying. A bad ground or low voltage can kill one just as fast.

Re: Walbro 255 fuel pump
 

I will post pics later today, but general ideal is that the Walbro 255 fuel pump is mounted along the fame rail, underneath the cab of the truck. I am using the stock fuel tank and sending unit. The fuel sending unit has been modified with a return provision, using -6an fittings. The stock sending unit has a sock on it that filters fuel from inside the the fuel tank. I don't know the microns, but I'm gonna assume it's 100. After the fuel pump, I have another small filter, an edelbrock inline filter that's 40 microns, and this fuel runs to a stock truck manifold, with the stock fuel rails, with a regulator on the fuel rails.

Re: Walbro 255 fuel pump
 

here is a pic of the modified stock Fuel sending unit. I hope you get the general idea. this an old pic. the 90 degree -6an fitting is the return line.

Re: Walbro 255 fuel pump
 

I don't know exactly how the 74 tank sits, and unfortunately google isn't being too helpful.

It does look like the 74 tank and sending unit exits from the top, and that there is no sump. How long is the distance from the pump to the output from the tank? The 255 will prefer to push fuel vs sucking fuel.

Re: Walbro 255 fuel pump
 

If I may, it could be the sock.

I was told when i did my swap to have the pump sit just a tad higher than the fuel outlet, place a 40 micron filter prior to the pump and a 100 after. I believe this is correct.

My pump is actually a Pierburg Pump. It is not as noisy as the Walbro and tons more reliable ( from what I have read). The Pierburg is stock in older Mercedes that run gas or diesel. but they are higher $ than a Walbro also.

Re: Walbro 255 fuel pump
 

ok, got all the pics I need to post, but they are not the best. its was dark outside when the pics were taken. I hope you get the general idea. the first pic is the stock, 1971 c10, in cab, fuel tank and the fuel sending unit. the tank is still in the cab. last pics is the same sending unit, prior to the mods. the second pic is of the fuel pump and second filter, as it heads to the fuel rail. the second filter is made by edelbrock. it's a 40 micron filter. the next pic is of the same.

Re: Walbro 255 fuel pump
 

So to clear this up clyde65 and br3w city, some adjustment may be needed to the placement of the fuel pump. moving it closer to the sending unit can be done but, who wants to hear an electric fuel pump inside the cab of the truck? not me of course. my budy has the exact set up, which I designed, but uses a msd 2225 fuel pump. its loud. he doesn't uses the edelbrock fuel filter either. I think he runs the corvette fuel filter regulator combo. well thanks for the input guys. Clark.

Re: Walbro 255 fuel pump
 

It might be worth trying to rig up a little bypass or try running without one or all of the filters.

A sock usually IS the pre filter, so your running a pre filter, then another pre-filter, then a post filter! I only run a single post filter, as the pumps are more resilient to debris than they are to restriction. I use a fuel cell, so i worry less about in tank debris, but even with your stock tank the MOST you'd need is a sock/strainer and then the regular post-pump filter.

Re: Walbro 255 fuel pump
 

Br3w City, where do you see pre filter, pre filter, and a post filter? Is the regulator on the stock fuel rail a filter? I thought Edelbrock was a post filter.

Re: Walbro 255 fuel pump
 

Maybe its the way I'm reading it. I saw
Sock
40Micron pre filter
100Micron Edlebrock post filter.

Assuming I read that right, thats 3 filters. The sock counts as the first pre filter.

Re: Walbro 255 fuel pump
 

br3w,
That was clyde69 that said "it could be the sock".... and that he had a 40m before and 100 after. I had to re-read it.
FWIW, I have a MSD pump and it is very loud, that is why my 68' pump is going in the tank!!!

Re: Walbro 255 fuel pump
 

FWIW, I have the idea to use the stock sending unit and adding the AC Delco EP381 pump to the sending unit. I gotta figure out away to add the electrical plug that come with chevy tbi sending units. I have had great success with that fuel pump. I know someone may be saying, just buy a rear mounted tank with the electric fuel pump provision. I say that it may be easier, but what's the fun in buy something when you make something yourself, that basically the same thing.