Replacing the fuel filter

[Bitsyncmaster]

I'm sure many of you have tried to replace your fuel filter and found that pipe feed line frozen in the compression elbow. Well mine is the same and first time I replaced the filter I left the pipe in the elbow and just unscrewed the filter from the NPT threaded end. This is a pain to do since you need to get that top hose connected and torqued with the copper crush washers. I guess many owners have damaged that feed line pipe trying to get it removed.

I could do the same and just twist the new filter back onto the NPT thread. But I was thinking maybe just install the 1/4" NPT to hose nipple on the filter and use 5/16" high pressure fuel hose. It looks like the pipe is 5/16" OD but if I cut off that frozen elbow then there will be no "barb" for the hose to hold onto. I would think two good hose clamps would work. Or I may be able to use a new compression fitting going to a 5/16" hose barb on the cut pipe.

Have any owners done this?

Also, why do they use foam between the filter and the mounting clamp?

[Helirich]

Sounds like good ideas. Please take pics.

[David T]

The fuel system in a Delorean is high pressure, higher than typical fuel injection systems. I would not recommend just slipping a hose onto a pipe without have a bead on the end. The reason those fittings are so tight is that they are steel, not copper and to deform it enough so it doesn't leak requires a LOT of force to tighten or loosen it. If you are going to use hose clamps and no bead at least put two clamps on each end of the hose and make sure the hose you use is rated for Ethanol and the pressure. Whatever you do DO NOT TWIST THE FUEL LINE! If you kink or twist the fuel line the only way to replace it is to remove the body. What some have done in the past if they wrecked the line is to abandon it and run another line. Not the best or cleanest solution but it does work.

[DMCMW Dave]

Have any owners done this?

Also, why do they use foam between the filter and the mounting clamp?

I have not seen it done exactly as you describe. I wouldn't be comfortable with the rubber hose on a non-barbed fitting. If you can find a compression fitting that is barbed on the other end that would be more acceptable. This is essentially what is done at the accumulator. Use the same hose and the same fuel-injection type clamps. Keep in mind that a fuel leak at the accumulator just falls out of the hole in the frame, where a fuel leak at the filter would spray all over the exhaust system. BE sure that there isn't excessive play in your setup, i.e. might need a bracket to support the fuel line a bit more since it would now be supported only by the rubber hose at that end.

The foam gasket is probably to keep the aluminum filter from touching the steel bracket (encourages corrosion due to dissimilar metals). Although the steel hose connection is not really different.

[Bitsyncmaster]

Well I decided to do it the old way and leave the supply pipe as is. Just have to guess when torquing the top banjo bolt. Real pain to get the filter mounting back in. I ran the pump until I heard the return line flushing back into the tank. Will road test later to see if the filter was causing my poor running (no power) under load.

I did look in the hardware store and they do have a 5/16" compression junction which would let you cut the pipe and then join it again. That would need your OD on the pipe to be clean so the brass ring would compress on it tightly. They also have compression to NPT fittings which would let you install a hose barb if you decided to go with fuel hose.

[dmcman73]

Well I decided to do it the old way and leave the supply pipe as is. Just have to guess when torquing the top banjo bolt. Real pain to get the filter mounting back in. I ran the pump until I heard the return line flushing back into the tank. Will road test later to see if the filter was causing my poor running (no power) under load.

I did look in the hardware store and they do have a 5/16" compression junction which would let you cut the pipe and then join it again. That would need your OD on the pipe to be clean so the brass ring would compress on it tightly. They also have compression to NPT fittings which would let you install a hose barb if you decided to go with fuel hose.

No power under load? Did you check for vacuum leaks?

[Bitsyncmaster]

No power under load? Did you check for vacuum leaks?

I've had the problem cold engine for a long time. Last drive I had it really bad even after it warmed up. So it happened pretty sudden. Will idle and accelerate fine not in gear so was just thinking about it and my fuel filter is about 16 years old. So that's my first guess.

[r00b]

I could never get my fuel filter off, I had to use a vice. I would have never been able to get it off otherwise, without damaging it. I really like quick connects so I used one of my banjo to quick connect on the top and a quick connect that threads into the bottom and points down. Now I just disconnect the old filter and move the fittings to the new filter.

20191122_161504.jpg20191122_161520.jpg

I was hoping to find a filter with the male quick connects built in but all I could find were rated up to 60 psi.

[Bitsyncmaster]

Well my problem was not the fuel filter. I changed the lambda and ignition ECU and I think the problem is still there but by then engine runs better since it's warmed up. I checked the dwell and it runs on the high side at idle but seems good (40 deg) when I hold high RPM. So I'm thinking it's something in the fuel distributor but I'm going to run a fuel pressure check after it cools down.

Problem showed up when I mounted my lambda ECU to the metal bracket. That is why I tested another lambda ECU. So I don't think the problem is caused by any thing I did.

[Helirich]

The fuel system in a Delorean is high pressure, higher than typical fuel injection systems. I would not recommend just slipping a hose onto a pipe without have a bead on the end.

There is another option. You can put just a slight flare on the end of the tube. It?s not as nice as a bead because the hose will not slide on as easy, but once you get it on and tighten a clamp, it can?t pull off. The key to this is make sure the tube end is debured good. I?ve done this (on other cars) with good results.