'86 MM fuel filter replacement tips needed

Hi everyone,

I'm trying to catch up some overdue maintenance on our '87 MM Sport. It has only around 118K miles and generally pulls pretty well, but just yesterday it decided to no longer idle. It will run all day if you keep your foot on the throttle but nothing without.

I can see the location of the filter above the frame rail in front of the fuel tank. Do I have to completely remove the tank or can I put a jack under the front end and lower just that portion to gain sufficient access?

I'd also appreciate any tips on the idle issue. I've replaced the PCV valve (the old one was grossly clogged) but that didn't resolve the idle issue.

thanks for any tips,

Mike

Ok, I've got the front tank mount off and the tank supported by a jack. I can now actually see the hose connections but no room to get in and clamp off the fuel lines and then disconnect. I'm going to see if removing access panel in the truck bed provides a topside access.

that was a dead end. No access to the underside from that panel. Looks like I need to release the tank's back mounting bracket and do it from underneath.

Well that was more difficult than it should have been. I was able to get the tank down, using my jack to support it, then wiggle the filter out and below the tank mid-seam. After pushing the filter towards the back of the truck I had just enough free length to get the hose clamps off. Barely enough room to clamp off the supply hose though. Got some gas from the old filter itself but was able to contain the mess.

Word of warning - I wouldn't advise using the Napa "gold" filter for this application as that particular filter has the input on the bottom of the filter housing instead of up at the top below the output. This makes getting the hoses on more challenging that need be.

So I'm happy to have a fresh fuel filter in the truck. Unfortunately the idle is still an issue.