Diesel fuel system problem

I have a Cat diesel engine which recently had the fuel injector pump overhauled. Since the overhaul it cranks quickly, runs for about 10 seconds then shuts off. The re-crank takes quite a while running the starter before the engine begins running again. Once running after the re-crank, it continues to run fine. I have looked for leaks in the fuel system and found none. I have re-torqued all the fuel fittings and it still does the same thing after it sits for awhile. I have looked for fuel leaks and find none. Anyone have suggestions as to fixing this issue?

My guess is the fuel system is letting in air somewhere, but where is the fuel going if that is the case?

I agree with your conclusion so far. How about some pictures of the injection pump and the rest of the fuel system? Or a model number if it's relatively original.

Is this on a generator application? Check the wires to fuel system and oil pressure just to make sure they have a good connection and thats not shutting it down.

I believe you are right, it’s sucking air somewhere. As to where- back up. What did you do and what did you touch? Check and and all fuel lines you removed. Were any of them flexible rubber lines? Were they brittle and or cracked? Did you flex any steel rigid lines? Forget or drop any copper washers?

Leakage issue causing a loss of prime.

Look at “unusual” suspects also. I have had a flame type intake heater nozzle leaking that caused an engine to loose prime after sitting overnight and need an extended cranking time. Customer was on the verge of having the injection pump replaced when I spotted the sign of a potential issue and the cure was a part that was less than a hundred bucks.

I once had a 580 L Case with the exact same symptoms, found a missing u type copper gasket on an injector return line banjo bolt

What cat Diesel engine .??
& what injection pump?? Mdl # off name plate if it has 1..

Yesterday I talked with my son who is an Aircraft A & P certified mechanic about the problem I was having. He said on turbine (diesel) aircraft engines, he has seen air bubbles left in the fuel supply line which which travel to the highest point in the system. When the system sets for awhile, supply pressure subsides, letting the bubble expand which in turn blocks the flow of fuel. Upon initial start, the engine runs until the injector pump runs out of fuel, then it quits. The extended restart period is needed to return adequate pressure on the supply side to overcome the expanded bubble blockage.

Since all the lines and filters on the system were removed and drained when the injector pump was overhauled, it was possible some air had been trapped in the system somewhere as a result. Based upon his advice, I re-purged the system again. I then re-cranked the engine and it ran fine without shutting down. Hopefully this will solve the problem permanently, but only time will tell.

Well the fuel system burping did not work in the long run. The comment by Melben got me to thinking about the banjo bolt seal washers, so I checked to see if they were all there, and they are. I put a little more torque on the bolts, but the situation was made worse. Then I remembered the mechanic broke one of the Banjo bolts on re-installation and lost a couple of the original washers which had a rubber seal built into them. He replaced them with generic copper washers without the built in ring seals, and a generic banjo bolt. Knowing manufacturers normally do not go to added expense without reason, tomorrow I will order new original ring seals and new banjo bolts and install them per the manual.

Seems the more you know, the more you do not know.

Knivens894 said:

Well the fuel system burping did not work in the long run. The comment by Melben got me to thinking about the banjo bolt seal washers, so I checked to see if they were all there, and they are. I put a little more torque on the bolts, but the situation was made worse. Then I remembered the mechanic broke one of the Banjo bolts on re-installation and lost a couple of the original washers which had a rubber seal built into them. He replaced them with generic copper washers without the built in ring seals, and a generic banjo bolt. Knowing manufacturers normally do not go to added expense without reason, tomorrow I will order new original ring seals and new banjo bolts and install them per the manual.

Seems the more you know, the more you do not know.

Click to expand...

the other thing you might try is double checking the “olives” on the fuel line fittings. When I took them a part on my backhoe they disintegrated.

Any luck getting info that pumpguy asked for? How about some pics like Delmer requested. I'd like to offer a little help as well but my magic 8-ball needs batteries.

Do you still have the broken banjo bolt? If so make sure it doesn't have some sort of check valve or restrictor. On a Volvo D-13 there is a "special" banjo with a check valve in the fuel filter housing, looks just like the other ones in the housing until you look inside...Truck will run and die just like your machine, ask me how I know..That happens once....

Thanks to all who offered suggestions in solving this issue, and particularly Melben. His experience was spot on the source of the problem I was having. I received the new OEM rings and banjo bolts Friday and installed them yesterday. In the interim, I talked with my favorite Cat field service rep, who agreed with Melben as to the probable cause. He went on to say most mechanics do not pay enough attention to the surfaces of the injectors and the rings the banjo bolts go through.

This was the first time the return header had been taken off of the engine. The surfaces still had paint on them from the factory, and two were dimpled from the banjo bolts. He said when the header is removed, it is easy to slightly bend, slightly changing the alignment with the injectors; and when reinstalled without cleaning up the surfaces such problems do occur because the washers cannot make a good seal. While I had it off, I cleaned up the surfaces using emery cloth backed by a piece of glass. It took off chunks of paint and revealed the dimpling which was also removed with the emery cloth. The new OEM rings and bolts I am happy to say, has solved the problem I was having. On multiple restarts, the problem is gone. Hallelujah!!! I do sincerely thank Melben for sharing his experience on the issue.

There were no flex fuel lines. The problem was the mating of the of the the return fittings to the injectors to the return manifold.

funwithfuel said:

Any luck getting info that pumpguy asked for? How about some pics like Delmer requested. I'd like to offer a little help as well but my magic 8-ball needs batteries.

Click to expand...

Why we can't get some basic information gets me on some of these problems!
Might as well post "I have a red car that won't work how can if fix it?"

And it's not just for the original poster but for someone doing a search for posts about a new problem months or years from now!

I'll go back and work on the red car and leave this one for someone else.

kshansen said:

Why we can't get some basic information gets me on some of these problems!
Might as well post "I have a red car that won't work how can if fix it?"

And it's not just for the original poster but for someone doing a search for posts about a new problem months or years from now!

I'll go back and work on the red car and leave this one for someone else.

Click to expand...

What color is the interior?

cosmaar1 said:

What color is the interior?

Click to expand...

Gray!

THATS HILARIOUS.!!!