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  #11  
Old 11-08-2018, 11:19 AM
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Pinching the return line on a Detroit wouldn't increase power. Their fuel is metered. It might on a Cummins as that engine uses a pressure/time type of injection.
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  #12  
Old 11-08-2018, 12:23 PM
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Originally Posted by MetalWolf View Post
I would look at the mechanical pump.... be sure it is or is not the problem
suspect it being mechanical it might have developed an air leak....

Gerry has the idea easy way to see if producing air
Or use a vacuum pump as rmack898 to check it to see if it bleeds down.
if you also have a fuel pressure gauge you can test it that way and see if it produces the correct pressure and holds or bleeds down....

There is two places fuel can go being a mechanical pump with a diaphragm the weep hole on the outer pump housing or internal back side of diaphragm
And if you find it is the mechanical pump...

I would not put an electric pump before or after the mechanical
either replace the mechanical pump or eliminate the mechanical all together and install an electrical... an be done with it....

And as digger doug mentioned it could also be a fuel return issue....
I have replaced every mechanical lift pump on the place with electric, except for the Dodge, it's already electric.

Mechanical pumps depend on the engine being rotated to bring up rail pressure, and in cold weather, that may be too much for the battery before a start. Electric pumps give better faster starting. And as Randal said, leave the mechanical out of the circuit.
My 544B loader, with a brand new lift pump, would be real hard starting after sitting a week, as the fuel would leak past the pump check valves and back to the tank. And usually pull air up through the return line.
An electric pump made a world of difference.
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  #13  
Old 11-08-2018, 12:42 PM
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Only Cummins experience I have is with the old Big Cam 350.

That engine has a different type of injection system. The "injector" pump pulls fuel from the tank, and puts it to the rail at relatively low pressure. The injectors fill from the rail, and an extra set of lifters on the valve lifter shaft activate the injector by pressurizing it mechanically. Extra set of lobes on the camshaft supply the motion to run the system.

Way to test the system is to test output pressure on the pump. Should be up to spec (forget what it is, have to look it up in my manual).

To test whether there's an air leak in the system from the tank to the pump, you attach a vacuum gage to the pump, and see if it's in spec. Too little vacuum means you got an air leak somewhere. Too much vacuum means you probably have a restriction in the system. (I had a no fuel problem, wouldn't run over 10mph, acted like it was starving......ran the test, found excess vacuum....WAS A METAL WASHER LODGED IN THE SHUTOFF VALVE IN THE FUEL TANK....JUST ENUFF FUEL GOT THRU THE HOLE IN THE WASHER TO MAKE THE ENGINE BARELY RUN. )

Air leaks aren't too hard to find. Pressurize the line somewhere just downstream from the tank, and look to see where fuel comes out upstream towards the pump. Just hook an air line to the fuel line, keep the pressure low, and see what's up.
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  #14  
Old 11-08-2018, 12:53 PM
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Another little trick with fuel filter replacement, or when you run the damn thing out of fuel (this applies to tractors, and whatnot, probably work on a truck too)

Lot of stuff has that silly little hand pump to prime the system once air gets into it. Forget that crap, and just crack a line near the pump, place your hand over the fill cap on the fuel tank, and use a blow gun to put air in the fuel tank (don't go crazy, you can mess up the tank with too much pressure, using your hand as a seal will allow you to regulate the pressure by spreading your fingers when it feels like it's getting above about 5psi).

Once fuel starts to come out of the cracked line, close 'er back up, and try to start the thing. Usually works the first time. May take a few tries sometimes.

If you still have problems, crack a line up on the rail, or somewhere on the output side of the pump, and do same.

I've seen guys run ether to the engine to try to pull fuel. Absolutely the worst thing to do to a diesel engine
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  #15  
Old 11-08-2018, 07:55 PM
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Originally Posted by Farmersamm View Post
Another little trick with fuel filter replacement, or when you run the damn thing out of fuel (this applies to tractors, and whatnot, probably work on a truck too)

Lot of stuff has that silly little hand pump to prime the system once air gets into it. Forget that crap, and just crack a line near the pump, place your hand over the fill cap on the fuel tank, and use a blow gun to put air in the fuel tank (don't go crazy, you can mess up the tank with too much pressure, using your hand as a seal will allow you to regulate the pressure by spreading your fingers when it feels like it's getting above about 5psi).

Once fuel starts to come out of the cracked line, close 'er back up, and try to start the thing. Usually works the first time. May take a few tries sometimes.

If you still have problems, crack a line up on the rail, or somewhere on the output side of the pump, and do same.

I've seen guys run ether to the engine to try to pull fuel. Absolutely the worst thing to do to a diesel engine
Actually The worst thing someone can do other than ether is use Acetylene an yep I've seen guys do it....
And all hell "brake" loose

So the new diesel safe Ether is not safe...
I've used it on the rare occasion never more than a 1/2 millisecond squirt

But then again I've seen kids put nitrous oxide on stock diesel engine too
but not everyone in the world can be accused of being smart.... but those are the ones smarter than everybody else too...
An apparently smarter than I by far...
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  #16  
Old 11-09-2018, 09:22 AM
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I am of the opinion that ether won't harm and engine if white smoke is coming out of the exhaust. If you are trying to light the diesel and the engine is too cold or the cranking speed is too low, a small sniff is all it takes.

I have also had employees destroy a Green Leaker by running it out of fuel and then feeding it ether, so I have seen the damage it causes when used as a sustiute for fuel.
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  #17  
Old 11-09-2018, 02:09 PM
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Originally Posted by Ironman View Post
I am of the opinion that ether won't harm and engine if white smoke is coming out of the exhaust. If you are trying to light the diesel and the engine is too cold or the cranking speed is too low, a small sniff is all it takes.

I have also had employees destroy a Green Leaker by running it out of fuel and then feeding it ether, so I have seen the damage it causes when used as a sustiute for fuel.
Yep I hear ya when it comes to ether a little sniff will do but I to have seen guys use up a whole can or two and only succeed in taking a small problem and making it a Huge problem then call me to come fix what cant be fixed at least not on the job site
had the one I was called out to where the guys used the two cans of ether on the backhoe cause it started then died a few minuets later, so out came the first can then the second then the call to go check it then point out no one turned the fuel back on but the damage was done so that is a classic situation of you cant fix stupid not even with duct tape.
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Last edited by MetalWolf; 11-09-2018 at 02:15 PM.
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  #18  
Old 11-09-2018, 04:48 PM
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Years ago two of us were underneath a truck working on the driveline and Toby was working on an old GMC dumptruck with a 6-71 in the next bay. The monkeys had laid it over on a jobsite and tore off the fuel line from the tank. He got the new fuel line on and was shooting it with ether while it bled itself out. Right about the time he gave it a big shot of ether it spit out the last of the air and got full fuel. Up until then I didn't know a 6-71 could sound like a B-17 on takeoff We looked over at Toby he had his arms wrapped around his head trying to shield himself from the blast. George looked at me grinned and said guess who just overrode the governor with ether. But, the Jimmy didn't let go and was back out on a jobsite a day or 2 later.
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  #19  
Old 11-09-2018, 09:25 PM
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Originally Posted by Whitetrash View Post
Years ago two of us were underneath a truck working on the driveline and Toby was working on an old GMC dumptruck with a 6-71 in the next bay. The monkeys had laid it over on a jobsite and tore off the fuel line from the tank. He got the new fuel line on and was shooting it with ether while it bled itself out. Right about the time he gave it a big shot of ether it spit out the last of the air and got full fuel. Up until then I didn't know a 6-71 could sound like a B-17 on takeoff We looked over at Toby he had his arms wrapped around his head trying to shield himself from the blast. George looked at me grinned and said guess who just overrode the governor with ether. But, the Jimmy didn't let go and was back out on a jobsite a day or 2 later.
Lmao. Guy two bays over had a trash truck that lost a turbo. No big deal, he’s a seasoned tech so he knows the ropes. Some time goes by and I hear the engine cranking. Then it skips right over idle and starts spooling hard like a high dollar pulling truck. Just keeps climbing. I took cover behind a city bus. It got to a point where I questioned just how much a stock rod can take on an ISL. Turns out they can do 4,200 and not have a problem.

Mouth breather did not clean the charge air cooler after the turbo failure pumped 3 gallons of engine oil into it. So when the engine started and the new turbo pushed a little air through the CAC it took some oil with it and bada bing bada boom!
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  #20  
Old 11-09-2018, 10:52 PM
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Quote:
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...so that is a classic situation of you cant fix stupid not even with duct tape.
I disagree... You need to wrap the entire roll around stupid's head and that WILL fix 'em... permanently!
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