fuel leak, intermittent

[RGT]

While driving on the highway yesterday I noticed a fuel smell, naturally I attributed it to some poorly maintained vehicle ahead of me... . when I got home and checked I can see a evidence of fuel on the front of the fuel tank and on the crossmember between it and the engine, I followed the fuel lines looking for any signs of fuel and can find none, my lift pump is dry as is my injector pump, even the back, the area around the injector pump is dry also... . I just finished driving the 35 miles to work and climbed under, in and, around and can find nothing. Is it possible the manual drain on the fuel filter let out a slug of fuel and then reseated itself?

Thanks for any ideas

 

[paccool]

Did you just fill the tank before this happened? If so, could be a leak around the vent and /or fill line to the tank. The airflow around things under the truck can be a little confusing. Just a thought.

 

[formula]

Did you recently change your oil? Some oils, RotellaT in particular, will emit a nice odor when they're new. My truck has oil in the same locations you describe, but it's not fuel. It is the oil mist that comes from the breather tube combined with the small leak in the vacuum pump / gear case gasket. When the engine is hot and running, get under the truck and have a sniff of the breather tube to see if that's the source of the smell.



Cheers,

Sean

 

[Bart]

I had the return line break on mine. Got home and the smell was there. There was a puddle under the truck at about the area of the rear of the engine drivers side. I noticed there was a short piece of rubber fuel line and aftermarket hose clamps back behing everything close to the engine block. So I got some 50 PSI hose and cut the return line up close to the injector pump and installed the longer rubber fuel line. No more leak and that was in May.

 

[RGT]

I was about 80 miles and 24 hrs from having filled the tank... . I am running Rosmella and am familiar with its scent... . all my lines are dry... but there was definately fuel on the undercarriagge and on the front face of the fuel tank, as well as some small droplets around the chassis. . I do get a light film of oil on stuff inline with the breather tube, but this fuel trail was further outboard of that, there is a plastic tube hanging down from the water dump valve on the fuel filter, it is not dry, but it's not wet like the crossmember and front of the tank were, I've got a few hundred more miles without the problem recurring..... thanks for the ideas though...

 

[formula]

I've had a filter drain valve leak. It was intermittent as you describe. Also, check the fuel lines where they go between the frame and trans crossmember to make sure they're not rubbing on it. (I see that you already checked the lines, but a double check can't hurt, eh ) On the return line up next to the firewall, there is a quick connector where the pump return and injector return lines T together, may want to have a look at that too.



Sean

 

[RGT]

It leaked again on the way home at the same distance from work( 30 miles) as the last time(several weeks and a couple of thousand miles ago) I pulled over this time and found fuel streaming out around where the throttle shaft goes into the injection pump, the truck was running so I grabbed the throttle linkage and revved it up a few times and the leak stopped. Now that I am home the pump is dry and the only evidence of this having occurred is the wetted underside of the truck, and the diminishing smell of fuel. Just before driving home today I installed a new throttle linkage, while adjusting it I worked the throttle between the low and high stops several times. I mention this as the last/first and only other time this has occured was when I was checking my TPS and the linkage adjustement during which I repeatedly worked the throttle between the low and high stops(engine off both times). The obvious is to just stop doing that... . Is it possible that it is just the throttleshaft seal and can this be replaced with the pump on the engine? or is itt likely to be the result of worn internals relating to the throttle shaft, and if so is it possible to make repairs to that with the pump on the engine?

 

[BushWakr - RIP]

The pump top has a bushing in it that the throttel shaft runs thru. In order to repair that the top needs to come off the pump, so it can be pressed out, and a new one pressed in.

If you remove the TPS, you can grab an allen key (8mm??) and try to snug up the bolt were the TPS end fits into. That is not only a TPS trigger but the allen lock screw that holds the shaft, springs etc. in place.

If it's tight, your bushing is pooched... and the shaft is shifting around causing the intermittent leak.

Eventually it will let go and you'll have a lot more fuel leaking. .



Bob.

 

[RGT]

Thanks Bob, can the pump top be removed with the pump on the engine? (I just read your gov spring install and see that I can)

 

[Clarkoh]

Same old

I had a similar leak. While running the injector pump would drip about once every 5-10 seconds. With the price of rebuilding, I waited. A slight loss of diesel was cheaper then rebuilding. NOW, I have the pump back after spending the BIG bucks. It got so bad my tailgate was slimy from the #2 collecting on it and I had to prime the low pressure side of the pump if it sat more than a few days. YUCK! The good news is the rate of rusting on the undercarriage has slowed for a while!

 

[RGT]

I replaced the bushing and throttle shaft, along with new seals today. I was able to pull the cover off the pump without backing off the timing or removing either the high or low idle adjustment screws(by using a ball end allen wrench) you can remove the cover with the power adjustment screw in, but should remove it prior to putting the cover on, as it loads the internal linkage significantly. One of the benefits of not removing the idle stop screws is that when you put it back togethor you know if you have the throtttle shaft indexed properly to the throttle plate your low and high settings will be correct, if incorrectly indexed the plate can be lifted up and repositioned one tooth back/forwrd to correct. When removing the cover you have to note that there is the governor spring connected to the bottom of the throttle shaft, inside the pump, rather than try and disconnect the spring and risk dropping the little linkage that it attaches to into the pump, I pushed the

 

[RGT]

throttle shaft down and out of the cover as the cover came off, clean the shaft end good before doing this as the shaft ends up laying inside the pump after it drops out of the cover. I was able to press the old bushing out with a couple of sockets and a bench vise, I pressed the new one in on a drill press, you need to apply some 5 minute epoxy to the outside of the new bushing when putting it in. I read through BW's directions for installing the 3k Gov spring at the beginning of this forum, the steps I have shown here are how I was able to do it differing from those instructions from input from the Dwight at Vigor diesel when I bought the parts,, and they worked great for me, I'd still be out there if I had tried to remove the low speed adjusting screw... I replaced the 2 throttle plates and their hold down nut along with the breakover spring. I hope this is understandable to anyone needing to do it, it is a very straight forward repair.