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Why did my 7.3 not like ether today.

Discussion in '6.9L IH & 7.3L IDI Diesels' started by franklin2, Aug 13, 2019.

  1. franklin2

    franklin2 Full Access Member

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    Preface; Did some work to the fuel system recently, ended up switching to and using the rear tank permanently, the front one rusted out. It has been doing fine till today.

    Today I noticed my fuel gauge was reading around 1/4 tank give or take. Thought to myself I am going to need fuel soon. Going home from work, hot day, A/C on, pulling a mountain, though unloaded, go over it everyday. Almost get to the top and it quits on me. Feels like it ran out of fuel. Got it off to the side of the road, got a ride home, got some fuel and brought my can of ether to help things out a little bit.

    Poured the fuel in, I had checked the schrader and it spit some fuel out so that was concerning me a little bit. I gave it a shot of ether, hoping it would run on that a little bit and I would not have to crank it so much. I started cranking and spun nicely till the ether hit the engine. Once the ether hit the engine struggled to turn over, much like a gas engine with the timing too far advanced.

    After the ether cleared it cranked fine, but did not start yet. Went out and tried the ether again, did the same thing. Cranking fast, ether hits and it struggles to crank, and by the way does not fire at all. After those two episodes I quit using the ether and just kept cranking it, and it finally picked up the fuel I had added and ran fine.

    So I did run out of fuel, I think I have the dreaded broken shower head on the fuel pickup tube. I think all that is explained, but I have no explanation why it did not like the ether when I gave it a shot. I never use ether unless I have a problem and I always have used it with success before when the engine was cold. This time the engine was hot. Is there a reason why it did not like the ether in this situation? There is nothing wrong with it, it runs fine, lots of power, NA, original injection pump and injectors with approx 140,000 miles on it.
     
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  2. Macrobb

    Macrobb Full Access Member

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    You've got the answer right there. Hot = ether ignites too far down on the compression stroke, so you lose power instead of gaining it.
     
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  3. franklin2

    franklin2 Full Access Member

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    I didn't know ether only works on a cold engine. Is there any type of fuel you can use on a hot engine that would help it along? Gas soaked rag trick? I know you need to be careful about putting any liquid down in it to avoid hydrolock.

    My batteries and starter are in good shape, so they got me going. But there can be circumstances where they give out on you and a little boost would be a good thing.
     
  4. Macrobb

    Macrobb Full Access Member

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    When it's hot, you could try gas fumes, or even diesel maby? You need something that's got a higher ignition temp like diesel so it won't pre-detonate.

    Personally, I just have working glow plugs. No worries about trying to get it started as long as it has fuel.
    As for priming, I will first crank with schraeder depressed till it runs clear, then floor it and crank till she starts(cycling starter as needed).

    Also, that's another advantage of having two tanks - I try to always be able to have something in at least one tank to swap over to, while driving - it starts to die, I swap tanks and drop it a gear while flooring it, using the vehicles momentum to crank the engine and prime.
     
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  5. Selahdoor

    Selahdoor Supporting Member Supporting Member

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    When the engine is hot, try WD40 or carburetor cleaner. (Not brake cleaner. Brake cleaner ignites sooner than carb cleaner.)

    I keep something in both tanks. I'll run one tank until it is half, or a third full. Never let it reach 1/4 or less. Then switch to the other tank. When the second tank gets near empty, I'll switch back to the first one, and head straight for the gas station. Fill them both. Leave it on that first tank. Lather rinse repeat.
     
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  6. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    The issue is you didn’t have any diesel being injected. Ether works fine on a cold or hot engine, but an idi won’t run on ether. It will help it ignite diesel if it’s present, like glow plugs, but it won’t run on it alone.
     
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  7. franklin2

    franklin2 Full Access Member

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    After I got it going I went straight to the fuel station and it took about 11 gallons. That is about right in my mind, about 5 gallons I can't use and about a 3 gallon reserve below when the gauge reads empty. I had the key on when I was filling the tank after I installed it, It read empty and slowly went up. So I am betting I have the pickup tube problem.

    Thanks for the replies.
     
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  8. BrianX128

    BrianX128 Supporting Member Supporting Member

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    This is how I learned that lesson, when I got my 7.3 it had 0 working glow plugs but 0 air intrusion and would smoke immediately when trying to crank. I gave it a small hit of either and it ran fine all the time. Once winter broke and I had joined on here I put glow plugs in and life was good. But between those events one day my fuel olive on my lift pump gave up and leaked all of my prime of fuel out while the truck faced up hill. Wouldn't do a thing. Killed batteries, and starter and a can if either trying to get it to fire. Got new batteries and a new starter which it probably needed anyways, but took the advice of someone on here and filled the fuel filter to the brim, and took the hard line off from the lift pump to the fuel filter and filled it with a tiny camp lantern funnel and fired right away. It was kinda neat learning how that worked all while being happy you didn't have a massive paperweight in the driveway lol..
     
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  9. Macrobb

    Macrobb Full Access Member

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    I disagree, to some extent. On a cold engine, you can generally get ether to run the engine, in that the RPMs will increase over cranking RPM, which will also provide more heat for combustion of diesel once it finally gets there.

    On a hot engine, you basically don't get anything out of the ether - it detonates on the compression cycle, slowing the engine down(ether lock); the presence of diesel alone is your primary factor as to whether the engine will start.
    It won't help with 'heat soak', for instance - where increasing the cranking revs will result in fuel being injected again and firing.
     
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  10. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Well I guess I consider an engine to be running if you don’t need the starter, just getting an increase is cranking speed isn’t really running imo. I have used ether on engines with hot start issues too.
     
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  11. BeastMaster

    BeastMaster Full Access Member

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    Does propane, dispensed from an unlit torch, into the air intake of a diesel help start it?
     
  12. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    You know Ive never tried, but it sure will add some power in a performance application by supplying more fuel, Im sure if you have enough it would run on it.
     
  13. Macrobb

    Macrobb Full Access Member

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    It depends on conditions, obviously - cold, probably not - the ignition temperature of propane is 878F, almost double diesels at 410F.
    Warm, well, I did manage to get an idi to idle on propane by itself. Obviously it took more than just a torch, though - we are talking 5 gallon tank, high pressure line and needle valve to get quite a bit of flow. It ran advanced(pinging/knocking), due to the autoignition temperature being reached before TDC, even at relatively low engine/cylinder temps.

    This is also why you have to be careful about propane injection - you have to inject less fuel than the Lower Flamability Limit so it doesn't ignite until the diesel is injected and the whole mixture ignites. Too much and you'll get the propane 'pinging' or pre-detonating, which kills power and is hard on the engine rotating bits.
     
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  14. BeastMaster

    BeastMaster Full Access Member

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    Thanks! I was considering what gaseous fuels I have around that might work in lieu of ether for coaxing a cold engine to start. Oh, well...
     
  15. dgr

    dgr Full Access Member

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    I'd crack the injectors lines loose at the injectors and crank it instead using ether on a hot engine. It'll fire on a few cylinders and as they start leaking fuel, you can tighten them.
     

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