The International Cessna^® 170 Association

This weekend I had to fix a small leak at the inlet fitting to the fuel pump on my ragwing. Every time I have to mess with this system, I start thinking that I'd rather have a firewall-mounted electric pump, "on for takeoff & landing" only.
I have copies of several 337's for electric pump installations by other ragwing owners. The trouble is, they all include an external bypass around the pump, plumbed using a couple t's and a checkvalve as per the original stock installation. This is to feed fuel when the pump is not in operation.
To me, this defeats half the purpose of the conversion to an electric pump: simplification. A friend used to own a Cessna 150-150, part of that engine conversion is installation of an electric fuel pump on the firewall.The fuel line goes from the gascolator, to the pump, to the carb. No t's, no checkvalve-- not required as the pump has an internal bypass. Nice & simple- if you don't have the bypass plumbing, it can't break or leak.
Does anyone on this board have a ragwing converted to an electric pump which doesn't use the bypass plumbing?
Another part of the appeal of the electric pump is cost. The Facet #478360 pump generally used for this purpose lists at about $60 new. The TCM # 40585 (AC#9051) mechanical pump costs about $300 for an overhauled unit, or close to $400 for a new one.
Has anyone ever sucessfully cross-referenced the TCM/AC part numbers to an automotive fuel pump part number? You know, "for testing purposes only" The identical automotive pump wouild probably go for $50 or less.

Eric

Eric, why can't you just utilize the same pump that's already approved on the C150-150 which already has the internal bypass? Wouldn't that be easier to get approved?

That is the pump I would want to use. But the trouble is getting the approval. The 150-150 engine conversion is an STC'd mod, the addition of the fuel pump is part of that STC. A conversion of the ragwing 170 to an electric fuel pump (from the mechanical pump) would be a field approval. The fact that a pump is approved for the 150-150 STC is not really relative to this situation-- it's comparing apples to oranges.
I haven't actually contacted the FAA regarding getting a field approval, I'm just going by what I've heard from others- that it's easier to get a field approval if you can show them documentation (337 etc) for a similar mod that has already been field approved. By similar I mean make/model specific- I doubt that they'd buy off on documentation based on similarity to a 150 modification.

Eric