Walbro 400 Fuel pump testing

**scheides** · 01-07-2012

Well I picked up one of these puppies up from MAP along with a fuel pressure gauge kit from Ultimate Racing during their xmas sale.

Installed the gauge first and tested on my current pump, DW300 and I was running pump gas:

43-44psi. I was shocked! Unmodified fuel system other than the DW300 and FIC1680's.

Converted back to e85 and pressure dropped at idle to ~40-41psi:

So I decided to forgo punching out the siphon right away and just throw in the new pump and see what I did. I was pretty shocked:

~44psi on the nose.

I'm running a boost-a-pump, and with the 1680's and DW301 pump I've been about at the limit of the fuel system since I converted to e85 in May/June. This pump very obviously flows more up top, time for most boost and more mods I guess?

**Kracka** · 01-07-2012

That's awesome! Glad you don't have to do any siphon drilling. Have you checked base fuel pressure with the 400 on pump yet?

**scheides** · 01-07-2012

Yup, that's the third pic. It's about 44.5-45psi, so base pressure definitely went up but not enough to warrant drilling.

I'm super glad I bought this pressure gauge setup. I was thinking I'd remove it after I finished this testing, but since I'd love to know if the siphon ever gets clogged (this is also a problem for some X owners apparently?) I might as well keep it, it was pretty cheap.

Lomker would be proud I think

**scheides** · 01-09-2012

SO. Yanked pump. Removed little filter thing, drilled siphon to 1.5mm. Reinstall, 42psi at idle and 46 with FPR off. Going in the right direction, I removed again and went to a 2mm bit. Reinstalled, back at 42psi at idle and 45-46 with the fpr removed. A little frustrated at the lack of change, I decided to leave it for now. I may eventually go down to 2.4mm but I want to make sure the siphon is still working properly.

Go for a rip, and yea...AFRs are notably better! I'm seeing 10.5 in a few spots!

Car rips, all 140lbs of spaz were with me tonight so I added that to the weight of the car

**goodhart** · 01-09-2012

Looks good man, what do you expect to gain once you lean it back out a tad? 25-30 HP/TQ?

turbotalon1g · 01-09-2012

I wonder how much whp can be made on this pump

**scheides** · 01-09-2012

Quote:

Originally Posted by goodhart

Looks good man, what do you expect to gain once you lean it back out a tad? 25-30 HP/TQ?

No idea. Gains from the actual pump will be zero, it's just fuel and I'll probably run AFRs right where I have been. I got it because I was leaning out up top when running a little higher boost on full e85 (not e70 like we have now) and I've also added the MAP rev3 IM and mil.spec 64mm TB, so i was worried about being even shorter on fuel. I figure this way I'm in much better shape.

Quote:

Originally Posted by turbotalon1g

I wonder how much whp can be made on this pump

Depends on the car. Remember I'm running this on a BAP right now. If I stumble upon some more cash in the next few months we shall see, but I'm pretty impressed with it thus far. I'm thinking on an X it would be perfect on a BBX Lite/FP Green/EF2 and maybe EF3 stock long-block setup on e85, depending on what supporting mods the car...skip the ported manifolds and tubular headers and I'd do dandy. Well come to think of it, Chris Carey has this pump on his car right now doing just that and it's fine (though he is on a rewire).

On a DSM or evo8/9, I dunno, I'm sure 500whp, maybe with a rewire.

**asshanson** · 01-09-2012

Did you get a pic of the pump with the filter on? Or is it just on the bottom side of the pump?

**scheides** · 01-09-2012

The filter looks just like a standard walbro, but it is a little bit bigger sock. Fits on almost exactly like a standard one does. I smashed it on and stuffed it into the hanger/cup, it fit right in.