fuel leak when engine is warm

[Mr. Bone]

Hello,

Any insight out there regarding fuel leaks when engine is warm on an '86 g30 6.2L? I am having a difficult time finding it. Thank you.

[wthif]

Sure it is occurring when the engine is warm and not just when the fuel system is pressurized? If you are not having problems starting I would start with all fuel return lines and the fuel pump if it is mechanical. Then try the supply lines after the fuel pump.

[Mr. Bone]

The leak happens when I've been running for while around town. As opposed to last night when i had not used it for a couple of days and idled it for 15 minutes and did NOT find any leaking. It seems the fuel sys. would be pressurized in that 15 min. idle. . . then again i do not know because of my lack of experience.

All the fuel return lines look great. As far as the fuel pump supply lines go, I do not know where those are. Do you know of a book that has schematics or pics of this engine. I am having a VERY HARD TIME finding reference material on the chevy 6.2L.

thank you.

[DmaxMaverick]

Do you have any idea about where it might be leaking? Front right, left, TC cover, fuel tank area? If it is the right front (passenger front) area, it could be the mechanical fuel pump or fuel filter assy. The M80 filter assy (on passenger side firewall) has known issues with cracking, causing intermitent leaks, and a mech. fuel pump will leak through a weep hole when it starts to fail. Other than that, it could be any part of the plumbing, and include the IP itself. If you have dual tanks, the switching valve has been known to leak on ocasion. A defective seal on the OEM filter could also be suspect.

[Mr. Bone]

thanks for the responses. The leak is in the middle front. . .b/tw the front wheels. Also, it then becomes incrediblely hard to start. Maybe this is common sense although to me if the system is pressurized any leaking fuel would be replaced by pressure in the system (depending on where the leak was coming from). thank you.

[DmaxMaverick]

Sounds like the fuel pump or a loose/damaged fuel line. Either could explain hard starting, as well.

[wthif]

I would agree with DmaxMaverick. The fuel is probably dripping down from the fuel pump or a supply line near it and then hitting the front cross member then dripping down to the ground. If the leak is before the pump air can get into the system making it hard to start.

[doncannon]

Hello All,

Mr. Bone: I was under my truck doing something not related to fuel and noticed that where the cab and bed meet underneath there was a leak. I looked closer and seen a cover that was wet and behind that one of the hoses had came loose.

hope this helps,
Don

[Mr. Bone]

Thanks for the help everyone. All thoughts are very appreciated. I'll see what i can see.

[doncannon]

hello all,

mr bone: keep us posted. curious to see what it is

Don

[ZZ]

I had an '85 Chevy 2500 /w a 6.2L "J" and it leaked at times around the throttle shaft. It never leaked down to where it was hard to start or anything. I tolerated it and drove it.

[Mr. Bone]

well, think I found the vacinity of the leak. Now I have to ID the part and check for the different spots it could be coming from. The part is brass colored flattened cylinder about 3" in diameter. It attaches directly into the block on the passenger side underneath - looks like an engine mount is directly above and to the left of it. Is this the fuel pump?? I can tell you just about anything you need to know on a 5 cyl. Mercedes diesel. . .this chevy is not even close in its layout and design of parts. Thanks for your time.:confused:

[DmaxMaverick]

That's the fuel pump.

[wthif]

Now I have to ID the part and check for the different spots it could be coming from. The part is brass colored flattened cylinder about 3" in diameter. It attaches directly into the block on the passenger side underneath - looks like an engine mount is directly above and to the left of it. Is this the fuel pump??

Yes that is the fuel pump and if it is leaking and not the lines connected to it, replace it.

[armadillo1]

Bypass it, block it off, and install an electric pump. It is well worth the money and effort.

[DmaxMaverick]

Bypass it, block it off, and install an electric pump. It is well worth the money and effort.

I don't agree. An electric pump has it's place, if you have a need for one. They do make priming a non issue, though.

A mechanical pump is very reliable, and will supply fuel under any demand, because it is RPM dependent. An electric has one speed, and can run short under high demand, especially later in its life. An electric can cause serious issues when it fails, including IP failure due to the pump itself causing contamination. A mechanical pump will just leak when it fails, and will still pump fuel while it's failing, and not dump trash into your fuel system. A mechanical will generally last 100K, or more, and requires no maintenance in between. No wires, switches, grounds, etc....and, they're much less expensive. Both are easy to replace.

Another thing to consider.
Adding an electric requires other additions, as well. You will need an electronic controller, or an oil pressure switch to ensure the pump doesn't run when the engine stops. It doesn't sound like a big deal, but if you have a collision, and a fuel line is ruptured, the electric will empty the fuel tank all over the scene. Not good, and not legal.

[Mr. Bone]

Thanks again for all the thoughts. NOW. . . how do i replace the lines or the pump and bleed the air out of the sys. from installation? Thanks!

[Mr. Bone]

Yes the leak was the fuel pump. It was coming from the weep holes(i guess that's what they are) in the top half of the pump cylinder. I believe it was spraying from them because there was fuel everywhere. Looks like a lot of the surrounding rubber was compromised - like the engine mounts. How big of a deal is it change the engine mounts (any opinions there)?

Thanks for all the input.

P.S. a bit of advice on screwing the steel fuel line into the pump that the diesel page troubleshooting guide does not give for vans. . .leave the pump mounting screws lose while threading the flare nut . In my case, without removing the alternator i cannot get to the brackets that hold the line further up the engine. So a lose pump while threading is the only alternative.