Good day!

I am wanting to replace the fuel filter on my 1986 Ford F150 (EFI). The truck has a 5.0 litre 302 with dual gas tanks. Am I correct in assuming that the fuel filter is located in the black plastic cup on the underside of the 'dual function reservoir'?

If this is indeed the case, why does it say "DO NOT REMOVE CUP" on the reservoir bowl? Does this bowl (cup) unscrew from the upper valve assembly? I can't seem to budge it loose.

If this is not the fuel filter housing, then could someone tell me where it is located on this particular model/year?

Many thanks...

 

That's one of them. You will have to take it completely out, put the whole thing gently in a vise, and get some channel locks to spin it off.

Here's one of the filters. http://contentinfo.autozone.com/znet...3802A/image/4/

Here's the other one.

http://contentinfo.autozone.com/znet...616DL/image/4/

See if those links work. Or you can go to Autozone's site and look them up.

 

The DFR filter is supposed to be a lifetime item but I had to replace that filter a couple of times due to the tank sender disintegrating. Can be unscrewed with a strap wrench. I think I used a lage pipe wrench on mine if I remember right. I eventually got rid of the DFR and went to an electric switching valve.. See details link in my signature. Note that if your DFR has been replaced with newer version then it may not have a filter inside. See photos on my site.

The main filter should be located just in front of the High Pressure pump on the drivers side frame rail. Near the drivers door.

From other threads.... some do not have the filter in front of the HP pump and have nothing but the DFR filter.
My '86 shop manual makes no mention of the HP filter in text or drawings.... So it may be something added in later builds or dealer installed. My '86 has it and it appears to be factory / dealer installed.

 

[quote=Franklin2;12353285]That's one of them. You will have to take it completely out, put the whole thing gently in a vise, and get some channel locks to spin it off.

Okay, thanks for that!

I had already removed the reservoir and attempted to unscrew the bowl with a strap wrench but it wouldn't budge. I thought I'd ask before I went any farther and risked damaging the unit.

I thought the warning about not removing the cup was confusing...

 

Thanks for that info. That's good to know too!

I did read that there are suppose to be two filters but my truck only appears to have just the one. I have a 'Haynes' manual for this truck but it only mentions the one filter before the pump.

I am trying to rectify a problem with the engine shutting down after running for a few minutes. There doesn't seem to be an ignition problem and the fuel pumps are all running so I'm guessing that there might be some sort of blockage in the DFR.

The sending unit in the front tank has ceased working so perhaps that might be a contributing factor to a possible fuel blockage as you had already mentioned...

 

The way the system works is that BOTH in tank pumps must be functional in order for the DFR to operate and switch properly. Fuel pressure from the selected tank pump moves the switching valve.

With the DFR off you can test he tank pump flow. This is the only way to test if the pumps are working. Hearing them does not tell you.
Run the hose from the tank into a bottle. The flow should be 16 oz / 10 sec.
You may need to jumper the fuel pin on the self test connector in order run the pumps that long, otherwise you have to have someone switch the key off and on several times. Details on my web page.
You could do the same test with DFR installed but disconnected at the HP pump to see if it fuel is flowing and switching properly.

Does the HP pump get loud and whine?
The engine will normally keep running with a bad tank pump unless of course something is totally blocked. Or like in my case one time the system was drawing from an empty tank when I has selected the other tank. The gauge indication does not mean the DFR is actually switched to that tank.

 

Yes, I've done what you've described. Thanks for mentioning it.

I removed the DFR and ran the pumps by jumping the FP test lead to GRND. The HP pump whines and there was fuel flow from both the front and rear tanks. Actually, I drained the front tank and will continue with draining the rear tank. This truck has been sitting for several months and I want to put fresh gas in both tanks after changing the DFR filter...

 

Well, I managed to install the new fuel filter cartridge by placing the DFR in a vice (as suggested) and removing the bowl with a strap wrench. The bowl was installed quite tight and I had to use a heat gun to warm-up the fuel bowl/DFR assembly before the bowl would unscrew.

The DFR fuel filter cartridge for this truck was a FRAM Part Number CG3790 (Ford Part Number E5TZ-9365-A). Perhaps that info might be of use to someone else with the same vehicle.

Before reinstalling the DFR/fuel filter assembly, I flushed out both fuel tanks and fuel lines with several gallons of clean gasoline to remove any debris and stale fuel.

After installing the DFR with the new fuel filter cartridge, the truck started and ran but shut down again after a few minutes. It's seems the initial problem was not rectified by replacement of the DFR fuel filter cartridge so I'm back to square one.

I've swapped out the ignition module and ignition coil with other used coils and modules but it made no difference. Also, I know all the fuel pumps are operating as this was verified by jumping the fuel pump test lead to GRND.

Would anyone have any other ideas as why the engine would shut down after running for only a few minutes???

 

I would see if it had any codes. Since you have a early truck, you might not have a fuel pressure test port, but if you do, hold a rag over it and poke it and see if you have fuel pressure. And test for spark.

Checking for codes is easy and you can use a testlight or old voltmeter to do it.

 

Thanks for the help!

This truck does indeed have a fuel test port but the focus is back on to an ignition problem. I had initially discounted an ignition problem because swapping out the coil and ignition module with spare units had made no difference.

The issue has now deteriorated to the point where the engine will crank fine but will not start at all (or starts and shuts within a few seconds). I then decided to test for spark. With the 'key-on' and remote cranking of the engine from under the hood, I found that there will be a few seconds of spark during the initial cranking then no spark at all.

I then replaced the ignition coil and the ignition module (in that order) with brand new items on the speculation that the used parts I had previously swapped out may have been faulty. Again, the new coil and module did not rectify the problem but they at least have been eliminated as a source of the problem.

I suppose the PCM (the computer) might be at fault but as I understand it is not likely as apparently they rarely fail. The only other thing that I can think of at the moment is possibly a bad distributor.

As it is now the truck has a new coil, a new ignition module and a new fuel filter in the DFR. There is good fuel flow (all the fuel pumps are working) but the spark is intermittent or non-existant...

 

I would just like to again say thank you so much for all the comments and suggestions. It is most appreciated!

The problem has been rectified by the replacement of the distributor. The failed component was the armature assembly (magnetic pick-up) of the Hall Effect distributor. The armature can be purchased separately but it involves the complete disassembly of the distributor for installation. I found the purchase and installation of a rebuilt distributor to be much less bother. Re-man distributors for this truck are available from UAP/NAPA

Neither the DFR fuel filter, the TFI module nor the ignition coil were at fault. I did not initially suspect an ignition problem because the engine would start and run for several minutes before shutting down and swapping out the coil and ignition modules with serviceable spares seemed to have no effect.

Even the failed armature would provide an initial spark during cranking before ceasing to function all together. I had since read about an identical fault with an 1986 Ford F150 fitted with the 300cu. in-line six cylinder engine so I suppose the issue is not rare.

Anyone else experiencing sudden engine shut-down or a 'no-spark' condition after initial cranking spark on these trucks might first want to consider a failed distributor armature...

 

Now that is it running, I would bone up on how to read the codes. It was probably giving you a code 18, or some other code related to that. The computer looks at the pulse train from the distributor, and uses that to adjust the timing. If it see's this pulse train suddenly missing, it will spit out a code.

The codes are not the "tell all" fix this and it will work. But they give good hints in the over all picture of the problem.

 

Yes, that's a good idea too!

A buddy of mine had a problem with a later model diesel F250 and the code given nailed the issue dead-on. I guess I was just being lazy. I've got a code reference manual laying around somewhere (I think it's at the bottom of a stack of 'Hustler' magazines) that I should dig out.

I also found on-line a guide for using a multimetre to verifying the serviceability of the TFI modules. I spent about a hundred and twenty bucks for a new module and a coil that the truck didn't need...