I'm trying to install an inline fuel pressure gauge. This afternoon I cut the fuel line to insert the gauge fitting but could not get it to fit.

My fuel line is 5/16" ID. The fitting is 3/8" OD. I've read that this should work, ie, that I should be able to force the 3/8" fitting into the slightly smaller fuel hose. However, if this is so, I've yet to figure out how. I've looked around online for a 5/16" fitting but couldn't find one anywhere (the fitting needs to have a 1/8 NPT port for the gauge).

So my questions are:

Should this work? Do I just need to apply more "elbow grease"?

If the answer to the above is "no", is the best alternate solution to simply replace the 5/16" fuel hose with 3/8" hose? The concern I have with this solution is that the fuel filter outlet nipple and the nipple to the fuel line running over to the fuel rail are not made for 3/8" hose.

Here's a couple links with photos of the fitting and the gauge I'm using:

http://www.jegs.com/webapp/wcs/stores/servlet/ProductDisplayPopup?storeId=10001&catalogId=10002&productId=763500&itemId=90480&langId=-1&showValue=1

http://www.jegs.com/webapp/wcs/stores/servlet/ProductDisplayPopup?storeId=10001&catalogId=10002&productId=763500&itemId=360725&langId=-1&showValue=1

I've read here that many have successfully made this mod, so I know the answer is close at hand.

Any help/advise is most appreciated.

You might try a hardware store. I used a brass tee with three 1/8" FPT holes with two 1/8' MPT to 5/16" hose barbs.

That was a good idea. I wasn't comfortable trying to cram a 3/8" barb into a 5/16" fuel line. And changing out the whole fuel line to 3/8" just to accomodate the 3/8" tee fitting was problematic as well.

So I went to Ace.

Got a brass tee fitting with 1/8" NPT holes (since this was what the threads on the gauge had). Screwed a couple 5/16" barb fittings into both ends and problem solved!

That was a good idea. I wasn't comfortable trying to cram a 3/8" barb into a 5/16" fuel line. And changing out the whole fuel line to 3/8" just to accomodate the 3/8" tee fitting was problematic as well.

So I went to Ace.

Got a brass tee fitting with 1/8" NPT holes (since this was what the threads on the gauge had). Screwed a couple 5/16" barb fittings into both ends and problem solved!

I worked part time at ACE Hardware for 5 years after I retired from Ralphs Grocery Co. In a way miss working there because anytime I needed little stuff like that, I was there. Plus I miss the employee discount.