Engine/Transmission (1994 - 1998) Another 12V Fuel Leak.

[JoeMartin]

Ok time for some info, I've got a 94 12V that last summer lost its Lift Pump, SO being in the side of the road I ran to the parts store got a small electric rattle pump and cut the line and installed it, worked for the moment.

Installed a New Lift Pump and went on my way back in June, Ran fine until about 2 months ago when it developed a very hard start problem, Cold/hot didn't make a differance. Looked here and talked with a bunch of local guys and everyone said it was the overflow valve on the injection pump, so i pulled it and replaced it, that worked fine for about 4 day and then the same thing again. loosened up the feed line from the filter to the pump when it was cold and there was no fuel at all so even with the small boost pump it wasn't getting fuel to the injection pump... Checked for air leaks all the normal stuff and finally got fed up and installed a Holley Blue pump on the frame rail.



Fixed one small leak on the pipe from the LP to the pre heater and this thing has never run so good. .



Here's the problem now, it looks like the LP is leaking from the primer altho its so easy to tell where its burried, but it leaks when running, Its only started since its been -10 for the past 5 days. I drove it yesterday and noticed the leak, ran around a bit with it and parked it until about 4 hrs later when i had to run out, I ran it a good 45 mins running in and out of places and this thing never leaked a drop...



Could it be the o ring on the primer? and if so why does it only leak sometimes and not all the time. Also it doesn't leak at all when its parked and shut down. . Any help would be appreciated before I get the bright idea to just burn it and start over with another truck. .



Joe.

 

[Joe G.]

Email me at -- email address removed -- for my write up on the 12 valve fuel supply system, how it works and how to fix it.

 

[BigPapa]

Joes da man on the fuel system leaks and pretty much anything else that goes wrong on our trucks.



Scott

 

[Flinty]

My '97 did the same thing when we had our sub zero weather here. I couldn't pin point the leak but it was for sure leaking. Being blessed with an extra truck I parked the '97 and drove the '92 so I could wait for warmer weather to mess with it. I heat my little shop with wood and I just couldn't muster the motivation. Well, then the '92 had issues (of course) so I was forced back to the '97. By then the temps were back up to tolerable levels and when I went lookin' for the leak it was gone. I've put about 3k miles on with out so much as a drop leaked. My advice: If you can wait for warmer weather the problem might go away! Also, take the fuel heater off.



https://www.turbodieselregister.com...sion-1994-1998/188234-lift-pump-question.html



Above is a link to a post of mine awhile back. Note the burnt prong on the fuel heater. I have removed four now on mine and friends' trucks and every one was fried. We saw plenty of cold weather here and none of us had problems with plugged filters, cold fuel, etc.



Luck. J

 

[tony597fitter]

I got fed up with leaks on the 12 valve mechanical sytem, either chasing air leaks or fuel leaks.

I installed an AirDog 150. New lines from the tank to the P-7100. No more lift pumps, heaters, or cruddy lines leaking anymore.

I did this almost 3 years ago and havent had ONE ploblem with fuel leaks or air in the lines.

Best $500 I spent. IMHO.

 

[JoeMartin]

Ok I ran the truck yesterday for almost 7 hours straight, gotta love pushing snow (not ) and I got a spot about the size of a quarter, SO iwent looking and its not the fuel heater, its not the lines its dripping right off where the rubber boot is for the primer plunger. I can't tell however if its running down from further up or not but it has slowed from what it was on my first post. . I did notice a little wetness on the top of the Fuel filter housing and the filter is a little wet. I've read that some people have had problems with that housing cracking. As I said I'm gonna try running it until it gets a little warmer and dryer around here and keep an eye on it to see what it does...



Just the kind of problems you don't need in this kind of weather... .

And joe I will e mail you for your info on this as I see you have had rave reviews.



Also one more question is it worth the money to get the remote filter kit as the fuel filter on this is not the funest thing to change.....



Thanks again all for the info. .



Joe.

 

[Joe G.]

The trick to changing the fuel filter is to remove the two nuts that fasten the master cylinder to the brake booster. Then lean the master cylinder toward the fender. That will give you plenty of room for your hands. The easiest way to break the filter loose is not a filter wrench. Use a big screwdriver like a chisel on the upper rim of the filter. A few good licks with a hammer on the screwdriver will break it lose so you can unscrew it by hand. The hardest part is disconnecting the WIF sensor. I use a little screwdriver to pry up the connector tab, but it's still kind of awkward.

 

[JoeMartin]

UPDATE... . Ok get this, I finally got PO'd last weekend and stuffed it in the garage as i couldn't take the leak anymore, I changed the water valve on the botom of the filter, Nope, Pulled the boot off the primer and it looked like it was pretty wet so I fought to get the plunger out of the lift pump ( with out removing it from the truck ) This is not recomended but it can be done. . LOL. Pulled the o ring and checked it looked good, pulled the inside seal and that looked good too, cleaned it all up put a new o vioton o ring on it and reinstalled it... Leak seem a little better but still there, So i proceeded to remove the pipe work that comes out of the lift pump to the pre heater as it was all new when i did the lift pump, it was all pipe taped and also pipe doped so it wouldn't leak. . Took it all apart cleaned everything and re taped it re doped it and put it all back together and reinstalled it... Presto the leak is gone, at least for the last week. . LOL. . Only thing i can figure is somehow it was getting past the pipe tape and also the pipe dope running onto the lift pump and then down from there... I'll keep you posted but for now its dry...



Joe Thanks for the info on the fuel system.....