Lost Prime In 674

[LinWI]

Hi
the gasket on the bottom of my primary fuel filter (diesel) was not seated properly and caused a slow drip. Today I took it off and reseated it correctly. Put the same filter back on, made sure the sediment bowl was clean, etc. This filter was originally put on last Fall.
I have now lost the prime, can't get fuel to come out of the relief valve on top of the secondary fuel filter. I filled the primary bowl and filter as much as I could with fuel before replacing it. Not out of fuel, and fuel lines are open. Can't figure out what tricks if any to try. Will it eventually re-prime if it sits long enough?

 

[caterpillar guy]

Well you could fill the tank completely full, or with caution you could use an air hose and a rag in the fill hole , and put some pressure on the tank to help it . I would guess you have a plugged line if it wont flow with the tank half full or so. You could also take the line loose from the tank and blow it backwards to rid it of anything plugging it.
Are you bleeding it in the correct order if not it will take some time to flow out. You should be bleeding the primary first then secondary then the high pressure pump.

 

[JimB2]

Hi, if you have an air compressor with an air gun, take the fuel tank filler cap off and insert the air gun into the full tank and seal around air gun with a clean cloth. Slightly pressurize the fuel tank and that should force the fuel through the system. After you get the air out of the fuel filters, continue to pressure the fuel tank, put the Stop/Start/Run lever on the Start position, put throttle on to 1/2 and then attempt to start engine. DO NOT CRANK engine more than a minute at a time. Let starter motor cool between attempts.
If engine still will not start, you will have to loosen an injector line at the rear of the injection pump.

JimB

 

[LinWI]

In priming them in the right order, I'm assuming I should loosen the acorn nut at the top, primary, then secondary, until I see fuel leaking out? Or should I loosen the screw at the bottom of the filter until some fuel leaks out? Which position should the relief valve on top of the secondary filter be in? Closed?

Not sure where/how to bleed the high pressure pump? Is that at the injector pump site?

 

[JimB2]

Hi there should be a bleed screw on top of each fuel filter. The bleed screw usually has a flat screw driver slot on top of the screw. Bleed the primary filter first(closest to fuel tank) then secondardy fuel filter. There are about 3 different fuel filter arranges on 674. There are the canister type with white drain on bottom, can type with glass bowl on bottom with drain screw in bowl. The drain screw is to drain off any water or sediment in bottom of bowl. There is no bleed screw on the injection pump. If the engine will not start with STOP/START/RUN in START position then you have to loosen an injector at rear of injection pump.

 

[LinWI]

Thanks, Jimb2.
Mine has the glass sediment bowl on the bottom, and only one relief valve over the secondary filter. Can't get any fuel out of the relief valve. I must have gotten air in the lines past that. I'll have to try cracking an injector line.

 

[JimB2]

Are you sure you don't have a clogged fuel line from the fuel tank. If you remove the fuel line from the tank that goes into the top of the primary filter the fuel should flow the full of the line from the tank. If you don't have good fuel flow, blow compressed air back towards tank. Unfortunately the fuel tank on the 74 series tractors are prone to collecting junk in the bottom blocking fuel flow. To fix problem correctly you will have to remove both shut off valves out of both sides of the fuel tank and drain the crap out of the bottom of the tank.

JimB

 

[LinWI]

No, I'm not sure about the junk in the line.
I tried opening a couple injector lines while it was being cranked, but nothing came out.
I tried pressurizing the fuel tank with the air compressor. That resulted in a few times of the engine trying to catch, but it would die again right away.
Tomorrow after work I'll try pulling off the main fuel line as you suggested.