If you are running a carb (as opposed to fuel injection), try and run a fuel pressure sender (transducer) with a pressure range of 0-15psi or 0-25psi. I run the 0-100psi in my car and find the accuracy and resolution not good, given I am dealing with 6-7psi of fuel pressure.

There should not be any issue using the 5V source from the SSI4 to power 2 or more pressure senders, as the total current draw from both devices should not exceed the SSI4 300mA limit.

Some of the pressure senders (transducers) on the market do not need a 5V powered source, they run off a 12V source and output 0-5V.

Make sure you follow Innovates recommendations for grounding all the sensors and the SSI4, DL32, LC1 etc or your readings may be less that accurate.