CUCV help!

[KYkid]

My '85 diesel CUCV had totally lost all power, and would just cut off at stop signs. I talked to some people and thought a dirty fuel filter was probably the cause of it.

So I took off the rectangular fuel filter and put on a new one, but now when I try to start it, the drain valve (at the bottom left of the assembly) just dumps gas out onto the ground. It's as tight as I can get it, what am I doing wrong? I've also got the air valve (on top of the fuel filter assy) tight.

I've heard something about diesels air locking when you change the fuel filter...is this a symptom of air locking?

 

[ntsqd]

Some of those drains are like those on the radiator, Left hand threads. Try turning it the other direction just to be sure.

 

[KYkid]

I took the fuel filter assembly off and after some inspection, I found that there's a little doughnut seal in the drain valve and it was turned sideways, keeping the valve from sealing. One of those easy fixes that takes forever to figure out.

However, I finally got my engine to start (without fuel leaks), but it seems to have the same problem I started out with: power gradually fades until not even flooring the pedal will keep it running.

What could be causing this? Maybe water in the tank? I haven't driven it all summer, so I guess that's possible. Thoughts?

 

[diesel4me]

fuel pump?..

I'm not familiar with CUCV's,--do they use a 'lift pump" on the engine for a fuel pump,or is it an electric pump ??..I'd suspect a bad lift pump if it has one,they usually cause hard starting, and insufficiennt fuel delivery if the diaphram in it is failing..air getting in the lines thru leaky fittings,loose clamps,or dry rotted fuel hoses can do it too(though usually its hell to start a diesel that has any air in the system)..could be rust in the fuel tank clogging the "sock" filter eventually after running awhile too..(an autopsy on the old fuel filter might help discover what gunk is in the tank or lines--cut it open with a hacksaw and look!)..An injector pump can "suck" enough fuel on its own even if the lift pump fails,to make the engine start and run--but it wont have much power,and act like its got a clogged filter..

You can put a peice of clear fuel line on the return line from the injector pump to the injectors to see if air bubbles are present--if so,its sucking air in the lines somewhere..also,if any of the return lines get plugged,the engine will shut off!--I learned in a GM manual you can shut off a 6.2 by pinching the return line shut..

The fuel shutoff solenoid in the injector pump usually either works,or it doesn't--but I suppose in rare cases it might stop the flow of fuel..I'd say its unlikely,but possible..


...It could be water in the fuel,(usually causes misfiring and surging though)--most GM diesels have a siphon hose factory that ends near the frame with a valve to let the water be siphoned out..on my 82 K20 its near the front most spring hanger on the rear spring..might not hurt to try draining out some fuel,and see if it looks like water is in it..I've used isopropanol dry gas in my diesel during the winter,said on the bottle "good for gas and diesel engines"..seemed to help some!--my truck gets driven very little in the warmer weather ,its mostly a work/plow truck....