My nice fuel pressure tester kit doesn't have an adapter that fits my 351W. The auto parts place's rental fuel pressure tester doesn't have an adapter that fits my 351W. Tried both on a friend's 351 and neither kit fits his either. Both kits have adapters that fit a 300 rail, interestingly enough. Searching online the only adapters I can find are labeled "Ford" - no help at all. Parts place has to special order any adapters to try - prepaid and no refunds. Uhg.

 

Same as a tire valve. I used a tire gauge to check my 351's pressure

 

I was not aware the test port on the fuel rail was different for the 4.9L vs 5.0/5.8L engines. My cheapo fuel pressure tester from Harbor Freight has the adapter for Ford vehicles. It has worked on all of my OBS trucks and the ******* Merkur I had several years ago. Do not recall if I had to use the adapter on my 2005 Navigator, probably did.

The adapter is 1/8" NPT to 1/16" NPT according to the at Summit: https://www.summitracing.com/parts/atm-3280

 

I must be the only one having this problem, which is why info is so hard to find on this. The valve is smaller than a tire valve, smaller than the 4.9 rail valve. I don't want to order adapters *****-nilly hoping one will accidentally fit. And, I cant use a generic NPT fitting because it wont depress the valve core.

I'm considering ordering a permanent gauge kit.

 

The cap fitting on the pressure gauge does not always engage the valve core when you put it on. What I've had to do before is to relieve pressure from the fuel rail by pushing on the valve core, remove it, then install the pressure gauge to measure the operational fuel pressure. When I'm done testing, I slowly remove the cap fitting to allow the pressurized fuel to escape, then re-install the valve core. So if you had to use a standard npt fitting, you can test pressure this way.

 

I just bought these adapters for my 351w and they fit the 5.0.

Innova 3649 - 4 pack for $14.74 - JB Tools on Walmart.com
or a few bucks more for shipping if you go directly to JB Tools.
https://www.walmart.com/ip/INNOVA-36...r-Kit/48349666

My Bosch/Actron fuel press. gauge screws right in to them and works great (and it comes with the Ford adapter)
Make sure the pins and o rings don't fall out of the fittings

 

Thanks for the links. And thanks to everyone. I'm not having a problem yet, but it's only a matter of time before I'll be glad I have the tools to make a quick diagnosis.