Fuel system leaks - suction side, air in lines etc.

[Jason O]

Hi Guys -

I've been reading alot of posts about fuel problems on the suction side of the systems. Fuel starvation, low side leaks allowing air in fuel lines, etc seem to be a common headache on our trucks.

One trick I have used is to install a short piece of clear vinyl tubing to use as a "sight glass" to see whats flowing to the lift pump. Air bubbles will show easily in the flow of greenish colored diesel.

The tubing comes in diameters from 1/4" on up. You will want some barbed hose fittings also. I'm not suggesting using this tubing as fuel line, but a piece spliced in while your troubleshooting may be helpful.

I tried this when repairing suction leaks on an MB diesel on my van and it worked well. Located an air leak in the fuel-water sep by having clear tubing on the inlet and outlet.

Hope this helps.

Jason

 

[doghead]

Great Idea!

 

[Jeepsinker]

That's the way the oldschool diesel mechanics used to do it. They used glass sight glasses though.

 

[kentuckycucv]

can the IP let air into the system?

 

[kentuckycucv]

I have the clear tube out of the top of the IP. I just installed an electric fuel pump. I cant find any fuel leaking out. but I have bubbles in my return. When I drive it runs out of fuel. I had a fuel leak the other night when it was Hot. I got a tow home. the leak seemed to be off the drivers side but in the morning no leak>>>>
I have a little sludge under the IP but it doesn't look like a lot. Im wonder if it is my Injector pump? I don't see any leakage from the rubber fuel line under the manifold. Do you think it is my fuel filter base? I drained the top and it didn't seem to have air. I think I might try and bypass the filter since I have a prefilter

 

[kentuckycucv]

My old filter base has the pressure sensor removed and blocked

 

[Jason O]

Kentucky - what motor are you working on? Your IP should be under positive pressure at the inlet, so any leaks would let fuel escape as opposed to letting air into the system. Is there a way you can put the clear line at the suction end of your electric pump.