Engine/Transmission (1994 - 1998) Fuel heater/ prefilter removal

[ALehman]

I want to remove the unit all together and replace with all new hoses. Should i run a hose from the transfer pump to the line on top of the heater? Also what else should i keep in mind?

 

[Vaughn MacKenzie]

ALehman I recently messed around with mine but in the end decided to leave it mostly stock.



There are some things you can do to improve what you got. First of all take the prefilter totally apart and replace all O-rings. There is one between the bottom bowl (Fleetguard pn 3845400-s wich includes a new prefilter screen) and one between the heater puck and mount head (Fleetguard PN 3834185-S). See here: http://dodgeram.org/tech/dsl/filter/pre-filt_clean.htm

Another thing to do is check to make sure your preheater is good. . . they often leak air around the electrodes when they go bad. Check with an ohmmeter, should be like 5-10 ohms. If it's infinite get a new unit, PN 3907766-S. Anyway bottom line. . . when I took my prefilter contraption apart I found all kinds of problems with it. Since this is on the vacuum side of the system it needs to be in great shape to be leak-free.



What I did on my truck was run -8AN fuel line from the tank to my prefilter and got rid of the hard line entering the prefilter. I had trouble with air sucking in here, I thought the fitting was crapola. I bought a 3/8" NPT-to-8AN adapter piece which I screwed into the fuel inlet on the prefilter, and used Aeroquip fittings on my fuel hose which I connected up to it.



I also replaced the rubber hose going between the prefilter and pump, and used real hose clamps instead of the spring jobs.



Another mod you can do is drill larger holes in the banjo bolts between the filter canister and injection pump, but I don't think this is a worthwhile effort on a 12v given the pumping power of the lift pump.



Back at the tank I went to town and put in a new pickup setup. I kept the antisiphon stuff in place but put a bigger tube leading up from it then -8AN fuel hose to a bulkhead fitting in the cap which my big fuel line connected to.



My post about my BOMBing here http://www.nwbombers.com/forum/index.php?showtopic=15869&hl=fuel



Vaughn

 

[biggy238]

So you have removed your steel lines on the frame completely? I ordered aeroquip equipment yesterday but i'm going to run it from just in front of the fuel tank and forward. I Think maybe this conversion might catch on. The other thing, about the

-AN. The conversion I found was to put the AN number over 16 (16ths of an inch).



That would make your system 1/2 inch I. D. and I went with -6AN on mine for 3/8" I. D.

I'm hoping I didn't screw up but it will only be a few fittings to make it right. If I get this installed to my Liking, my fuel return line is next.

 

[The patriot]

If you'd like to remove it all together, go ahead, you may be better off.

I'd run it from the tank to the secondary filter, but ANY primary filter would make me feel better.

I had a leak that I couldnt find. I took off the heater element from the pre filter body, then assemble the unit w/o the heater. The wires were toast.

It was better, but still not right.

I started looking at the lift pump because I was sure the O. F. valve was in spec.

After doing the LP, it's 100% better!!!

I still bought an O. F. valve, but I'm running it as is because the fuel pressure is within spec.

You'll get a lot more in the complete post if you use my name and search for lift pump.

Too much to type here.

Eric

 

[Andy Redmond]

I caution our nothern friends against removal for other than diagnostic purposes. The heater will warm the fuel to prevent gelling in severe cold temps. Often although idling is not good for other reasons it will circulate enough fuel then back to the tank to prevent gelling in most instances.



I have cranked many 12v's in Dodges in -15 thru -20 below zero with no block heater and treated no 1 diesel when snowmobiling in Wyoming. They sure sputter and clatter, but its possible after a few cycles of the grid heater (make sure your batteries are in top shape).



Off my soap box about changing a part that has served well for how many miles and a new one will likely go the same distance.



Good luck

Andy

 

[biggy238]

I'm noticing a trend that it's the 94-96 trucks popping up. I wonder if it's hardware or just a fad?



I live in southern Ky. So I will probably survive without mine, but north of here I know better. I've started all too many tractors in winter and had my rear freeze to the seat. Fuel heaters warrant replacement.

 

[Vaughn MacKenzie]

So you have removed your steel lines on the frame completely?

Nope, left them in place. I put a plug in the old supply line but still use the stock return line.

The other thing, about the

-AN. The conversion I found was to put the AN number over 16 (16ths of an inch).



That would make your system 1/2 inch I. D. and I went with -6AN on mine for 3/8" I. D.

I realize this. I originally planned to go with -6AN but when I whipped out the measuring tape and checked the ID of the fittings it was barely more than 1/4" ID. This isn't much of an improvement over stock. I decided to see what -8AN gave me and I measured 3/8" so that's why I went that route. I think the -AN system bites. . . if it's -6AN then by golly the ID better be 3/8"!! Take a ruler and check it out, you may want to consider sending the -6AN back.



Vaughn

 

[Vaughn MacKenzie]

Here are a couple pics. Sorry the one of the fuel pickup is hard to see. The truck is parked on the street and it's about 100 today--pavement's a bit toasty. Will get some better pics later.



On the pickup the only spot out of the 4 that will work is the 6-o'clock position (12-o'clock is toward the front of the truck). It took about 13' of hose for my CC longbed but as you can see it was a bit long (better than being too short) :-laf



Vaughn

 

[Katmandu]

Where's the cheapest place to buy a replacement fuel heater ??