Bought a gauge set for an I/O and will actually be using them on a fuel injected outboard. The set has an oil pressure gauge but no fuel pressure gauge, would the oil pressure sending unit be fuel compatible? Or could I possibly use the fuel pressure sender with the oil pressure gauge. I know it is kinda a goofy question but it is "budget" build and I have spent way too much on it already.

If it's a budget deal go for it. worst can happen is u have to change out. Around the shop I've used various gauges for multiple different uses including fuel pressure and by surprise they worked. I would think the senders would be the same and more than likely will get reading on gauges but how accurate not sure. Ck water section u might find some otherwise. Is it fuel injection application?

It would just bug me like no tomorrow but hey.....

Is it electric or mechanical gauge?

Should work just fine. just don't confuse the two gauges.

Let me clarify, 2 stroke 2.5 merc racing outboard, so fuel pressure and oil pressure are the same if you really think about it....lol