As our beloved Cummins trucks age we are seeing more and more starting problems related to low fuel pressure. These problems can be very frustrating if you have no way to tell what's going on. Now you can install a quick gauge for temporary diagnosis or leave it on permanently. This silicone filled dampened gauge fits right on the top of the fuel filter on 12 valve Cummins engines in Dodge pickups. Just remove the existing banjo bolt in the top of the filter and replace with our stainless steel banjo bolt/snubber/Gauge & new washer combination. That's it! Now if you have a starting problem you can quickly lift the hood and see if it's a fuel related problem or not. While cranking you should see at least 15psi. If not you have a fuel supply or pressure problem. This is the most important gauge there is when you are having problems diagnosing any diesel engine. This gauge fits in a 42mm hole.