[Richard L]

A good voltage clamp is more involved than a few resistor. Example below:

1 Zener diode based map clamp:
It a low cost solution, a 4.7V zener will clamp any voltage above 4,7V but it is a very soft clamp, ie, it will start clamping from 4... 4.2 .... 4.5V etc. This will effect affect the MAP sensor voltage and your fueling will not be as accurately above 4V.

2. Active voltage clamp:
Using integrated circuit or chip to allow a very sharp and accurate point, normally use ajustable betweem 4.3-5V. Aquamist makes those devices for many companies but not advertised as our normal range.