1990 W250 Difficult Starting

[Ironforger]

Wow, first time ever for this.  Truck has been reliable for years. Always consistently started right up with just a touch of the key, cold or not.

 

Now, suddenly one moring I go to start it up, it started for a few seconds then died. Tried it again, same thing.  Tried it again, gave it some pedal then it started & ran fine afterwards. Good power idles fine.

 

Issue only occurs when attempting to start.  Seems it will only start if I pump the accelerator pedal while cranking.

 

My first thought is fuel filter? Just picked one up yeterday, will try to install Saturday. Finally supposed to warm up here in NJ!

 

Any tips or advice greatly appreciated.

 

 

Thanks!

[Wild and Free]

At that age I would be replacing all the rubber fuel lines as well, they could be dried out and starting to crack and allow some air into the system.

[Ironforger]

Fixed.

Diagnosis: Supply line leak pre-lift pump. Supply/suction line was rusted. There was a small hole at the first bend off the tank.

I ran a new rubber fuel line (Diesel compatible of course) from the tank to the lift pump. Luckily didn't have to drop the fuel tank. Being skinny and working from the driver side rear wheel well I had just enough room to reach up under the body to remove old line from fuel tank and clamp on new rubber line.

Once the new line was in I purged everything as follows: loosen the inlet banjo bolt on the fuel filter housing, operate hand lever on lift pump until fuel squirts out, tighten banjo. Next, removed fuel supply line at injection pump & place in small plastic bottle (spring water bottle). Operate lift pump hand lever until clear bubble free fuel squirts out. Replace fuel line, but don't tighten. Operate lift pump again until fuel leaks out around fuel line nut. Tighten nut. Next, cracked all injector lines on the head and cranked engine until fuel squirted out all lines. Tightened all injector lines & truck started up. Runs fine now.