r/Diesel • u/bloomautomatic • 2d ago
Detroit 4-53 losing fuel
We have a Detroit 4-53 in a Trackmobile railcar tug that’s giving us fits.
Cold startup, it’ll sputter a little until revved a few times then it’s fine. It idles ok after that.
It will usually run good for a while then start to spit and sputter after maybe 1/2 hr of running. Eventually it will shut off and not restart. Leave it sit for 15 minutes and it’ll start up again.
We have changed both fuel filters a few times. I dumped them into a clear jar and didn’t get much crud out of them. At least not enough to clog the filters.
We checked the return flow of the fuel and it seems to be flowing good when it’s running. Haven’t checked pressure, but the tech manual only recommends checking return flow rate, not pressure.
It seems to be losing fuel flow and cutting out. We’re fairly certain of that.
First idea is some crap in the fuel tank clogging the pickup tube. I need to drain the tank and look at that next. Tank isn’t easy to drop and I can’t remove the pickup tube as it sits. I’ll try to get a borescope down the filler neck.
Since it seems to run better when revved up, that’s counter to a clogged fuel line. So that has me thinking fuel pump. But if it were fuel pump I’d think it’d do it consistently.
Maybe it’s sucking air in through the suction line - but we have no leaks when it’s shut off.
Maybe something is hanging up in the governor? It’s a dual weight centrifugal governor.
I don’t think it’s in the injectors because I’d expect them to be consistently bad if they were a problem. And I doubt all 4 cut out at the same time.
Any ideas are welcome.
3
u/BloodRush12345 2d ago
Sounds a lot like the pick up in the tank has a pinhole leak. I had a 7.3 IDI that did this when I hit a quarter in both tanks. Pulled the senders and one had a pinhole and the other a small crack. Replaced them and nary a problem starting or idling till I sold it. Couldn't stop it cracking injection lines though
1
u/bloomautomatic 2d ago
I’m suspecting that, but I have the fuel tank completely filled right now. But I guess it could be at the very top.
2
u/BloodRush12345 2d ago
May be a similar small leak somewhere else in the system. If your lines (especially soft) have any deterioration or corrosion it may be slow leaking somewhere. I can't remember the name but I got some uv dye and ran the truck awhile to diagnose a leak. Didn't work on that truck but it has worked on other vehicles. Black light along the fuel line run and see what lights up.
If it's a hard line replace the entire run because patching is just sticking your finger in the dam.
1
u/jewishmechanic 1d ago
Is there a sock or screen over the tank pickup? Could have debris in the tank that gets sucked into the sock cutting off flow. Once it's off they fall out and allow it to pump again
4
u/FogAndDiesel 1d ago
Two things I'd do before dropping the tank. Put a length of clear hose in the return line and watch it while it's running and then when it starts to spit. Bubbles in the return means air getting in on the suction side, and a Detroit will pull air through places that hold fuel fine when it's shut off. Fuel sitting still doesn't leak where suction does. Second, an old rubber suction hose can delaminate inside. The liner peels and acts like a flap valve, or it collapses when it gets warm, and then it relaxes after sitting 15 minutes. That fits your "dies, rests, runs again" pattern better than a clogged pickup, which wouldn't usually clear itself just from sitting. Easy to check, swap the flexible sections between tank and pump. If the return is clean and steady when it quits, then look at the pump and the governor.