Engine/Transmission (1994 - 1998) Fuel Leak

[Denis]

Have a fuel leak on the driver's side of my '97 3/4 ton truck. Started smelling diesel as I got out of my truck about a month or so ago. Last week noticed a small spot under the front of my truck which had a diesel smell so I used engine cleaner to throughly clean the driver's side and searched for the leak but to no avail. Can see nothing from the top side but when I crawl under and look up I can see some drops of diesel on the starter but can not pin point the source. Any body have this problem? Can any body offer any suggestions?

I have checked the visible fuel lines, the fuel filter and water drain valve and screen housing on bottom of the fuel pump already.

 

[JGheen]

What about your lift pump or pre-filter housing? I have heard of the pre-filter housing gasket leaking over time. How many miles are on the rig and have you ever had any fuel related parts replaced before?

 

[BPINE]

It is most likely the fuel return hose from the injection pump.

 

[Joe G.]

There are some other places that can leak.



Push button on lift pump. If that it leaking the push button will unscrew. It's plastic so be careful. Replace the larger O-ring.



The input fitting to the fuel filter. If it's leaking replace the four banjo fitting gaskets.



The fuel heater. If it's leaking it will probably be from where the wiring harness connects. You can remove the fuel heater until you can get another. Remove the pre-filter with a 18mm socket. Remove the fuel heater with an 8mm allen wrench. Leave the heater off and replace the pre-filter.



Check the stuff recommended above.

 

[JGheen]

Originally posted by Joe G.





Push button on lift pump. If that it leaking the push button will unscrew. It's plastic so be careful. Replace the larger O-ring.



The fuel heater. If it's leaking it will probably be from where the wiring harness connects. You can remove the fuel heater until you can get another. Remove the pre-filter with a 18mm socket. Remove the fuel heater with an 8mm allen wrench. Leave the heater off and replace the pre-filter.

How does the push button unscrew? Isn't there a set screw holding it on or is it just righty tighty, lefty loosy? Is the O-ring under the rubber flex boot, so when you remove the knob, you remove the rubber boot and the o-ring is exposed? Do you have an illustration possibly?



Isn't there an o-ring where the wire harness connects or a sealing washer? When one removes the fuel heater, you leave the harness in the pre-filter housing and just disconnect the harness QD?

I am still waiting for my Dodge service manual from Chrystler, so bear with my questions. Hopefully it will get here soon and I'll have a better idea of what everthing looks like internally and externally...

 

[Joe G.]

Remove the push button cover by just prying it off. Then you will see that the push button has a hex on it so a wrench will fit. Actually, it's plastic so you can unscrew it with a pair of channel lock pliers pretty easy. The whole button assemble comes out. There is a large O-ring that can be replaced. If it's leaking there will be fuel under the button cover when you remove it. If it's dry then just put the cover back on.



The fuel heater will most probably leak from inside the electrical connector. No sealing gasket or O-ring. What happens is that a connector pin burns off inside the heater. This makes it leak around the connector pin.

 

[JGheen]

Originally posted by Joe G.





The fuel heater will most probably leak from inside the electrical connector. No sealing gasket or O-ring. What happens is that a connector pin burns off inside the heater. This makes it leak around the connector pin.

I know this has been discussed before, but the connector pin burning off is a rare short that can cause the fuel heater fire that was talked about on another thread, right? I think I am just gonna disconnect the heater since summer is just about here in So. Cal. I can do without an unecessary fire, especially on my road trip up-state tomorrow for the weekend.

 

[Joe G.]

I don't think it's a short. It overheats and burns in two. If you disconnect the electrical connector that won't fix the leak if that is what is happening. The point being made above is that lots of things can cause a leak so you have to investigate the possibilites. Just changing parts just in case that is the leak is not a good idea. Find it first and then fix it.

 

[Denis]

Found leak

The leak is from the hand priming section of the lift pump. Thanks to Joe. Next question; if I remove the plastic plunger, will fuel syphon out of the cylinder it was removed from?? Does anybody know the part number of the "O" rings needed and also the rubber cover for the plunger??