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Onan 7.5DKDFL - A good fit for me?


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  #61  
Old 01-15-2018, 01:44:37 AM
DieselBound DieselBound is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

SUCCESS!

I installed the new Hubbell plug and I STILL didn't have requisite voltage, I measured 107v at a receptacle. Accessing at the generator's breaker looked to be too messy so I went ahead and measured at the plug end (disconnected from run). The voltages seemed to be moving around quite a bit. Decided to just plug it in and get it loaded down and see what would happen.

Initially I was seeing about 111v. Acceptable. And then after a bit with various household stuff running I was seeing 115v up to 119v. Seemed to settle down and ran mostly at 118v.

Hz was measured at 61.47. I only made one measurement and I can't recall at what point in this run cycle I'd made it.

No problems with my UPSes.

Anyway, I'm thinking that this was all a matter of a generator needing to be exercised with a good load. I had not done this in quite some time: I'd embarrass myself by saying how long I think it had been. The Leviton plug really needed to go, and I suppose this was all a good reason to have done that: the Hubbell makes for a very clean install/connection.

I'm losing prime (since replacing the fuel lines from/to the tank) and I suspect that it's the fuel line quick connects (marine) to the fuel tank.
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  #62  
Old 02-14-2018, 01:53:55 PM
DieselBound DieselBound is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

Still fighting the darn fueling issues! Now, however, I'm thinking that I'm getting a blockage at the fuel pick-up as the in-line primer bulb (new) is collapsing (before, when I was sure I was having air issues, it wasn't collapsing). Given the little fuel that this engine consumes it will run for some time before this becomes an issue (a good 10 minutes). BUT...

When working on the fueling issues (discovering that it's still not licked), I discovered that I'm once, again, having voltage output problems. I was getting about 83V at various outlets. Tried applying more loads thinking that it might "shake" things up, but no change. I checked voltages at the plug from the generator (disconnected) and I'm getting 114V. Where should I start trying to troubleshoot?

I've checked (loosened and then re-tightened) the wires at the receptacle. There's a J-box in the run (on the other side of the wall) and I'm going to be checking there: can't recall if there's a splice or whether it's just a pull box- this was all done by an electrician.

Is it even possible for a wiring run to have an issue that would result in a power drop like this? Running four wires: (2) 120V, (1) common and (1) ground.

The generator isn't really responding to a load. That is, it doesn't sound like it's ramping up in power. The fueling issue is possibly causing me problems here, though I cant' see how it can be doing so during the initial run-time as the primer bulb and line will be delivering ample amount of fuel (I'm thinking- though if there's excessive vacuum from any blockage [never an issue before] maybe?).
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  #63  
Old 03-04-2018, 08:45:41 PM
DieselBound DieselBound is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

This is turning out to be one of the most difficult pieces of machinery I've ever dealt with!

Generator has gone from running and producing proper voltage to running and producing low voltage, and now it's not running at all.

I had been trying to troubleshoot the low voltage issue (discussion in a separate thread. Was needing to do one more test on the electronic voltage regulator and the Start/Stop switch self-destructed! Got a new switch and installed...

Now I'm not able to get the engine to run. I've had it fire but it won't catch. Seems I'm only getting fuel out of the #1 and #3 injector lines: some time back while bleeding I recall getting fuel out of the #3 injector line. Just dribbles, with a bit of bubbles. I keep working it as though it's an air issue and then the 30 amp fuse decides to blow!

I'd pulled that 30 amp fuse just to check it. Again, I just touch stuff and it fails on me! I'll now have to make a special trip into town to get a stupid fuse (I'll, of course, get multiple ones).

The fuel solenoid seems to engage just fine.

No clue whatsoever. Not sure if there's some electrical feedback (control board or regulator board) that is responsible for the engine not starting/staying running. And now that I have a fuse blowing it's going to stall me out even more.

I really want to get this thing operational so I can get it out of my garage (I've got blown head gaskets on my truck- when it rains it pours!).

I'm about ready to start looking at a new generator. I wasn't wanting a generator as a hobby (I need it for backup power).
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  #64  
Old 03-04-2018, 09:24:25 PM
nothingbutdarts nothingbutdarts is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

What kind of a fuel pump and tank do you have? Are you able to watch the return fuel back to the tank to see if there are air bubbles which there should not be.
You need to make sure while you are cranking it that the electric fuel shut off solenoid is pulled all the way in.
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  #65  
Old 03-04-2018, 10:03:27 PM
TLB01 TLB01 is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

Mechanical fuel pump. Not seeing a return.

It should plainly be visible from the pics, unless I am finally ready for glasses. Should be off the left hand side of the fuel rail. Smaller diameter line than the feed so there should be two lines visible up to that outboard fuel tank.

The engine is surging in the youtube. That rain flapper on the exhaust should not bob. That engine is not entirely in its happy place.

How is this thing hooked up to your house? Just wondering. You stuck a polarity cube on any outlets when its hooked up to the house? It might not hurt to unearth that breaker on the side of your control box and take some readings off the lines going to it. Your woes might be the fuel return and how you connected it to your house.

Anyway, don't give up. You have a really good set. Its not a "Hobby Generator". Its legit.

I have DKD spec F myself and its a phenomenal little machine that came to me as a pile of rusty parts on a pallet from Wisconsin. Its one of the few gens I have owned that I can sleep easy at night with it running. From a "Its not going to blow up before dawn" or "Run out of fuel quickly" standpoint as well as not being so loud to keep me awake or bring down the wrath of the neighbors. Still, its a 30+ year old machine. It going to require maintenance and attention.

Anyway, some how I keep it going perfectly in spite of myself and its definitely not Johnny C rated.

Last edited by TLB01; 03-04-2018 at 10:19:16 PM.
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  #66  
Old 03-04-2018, 10:33:50 PM
DieselBound DieselBound is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

I have the generator disconnected right now. I did have it running, and running smoothly (previous videos were initial running- I think this was when I had just gotten it and it was still in the back of my truck). I don't believe that it should have mattered, but I didn't have the neutral bond broken when I had it hooked up to the house: hooked up via genset plug and then to the main panel switched using an interlock kit- I ran for some time, a good 118v): I now know what I have to do to sort that out for properly connecting.

Last time I was running it and it was outputting 83v the engine would not engage in any added load- continued to run as though unloaded.

I had struggled with some fueling issues, air incursion, but I finally resolved those (I did end up hooking the outboard fuel connectors flipped on their respective barbs and that resulted in sucking the primer bulb flat)

And while further on the path to investigating the low voltage issue the generator stopped running. Since then it's not been able to stay running.

I dumped fuel out of the main filter and drained just a bit from the water separator to ensure I didn't have any water: none found. I think that the filters are refilled with fuel now: cracked the bleed bolt on top of main filter head and it's pushing out fuel.

What is the lever on the side of the fuel pump (round thingy below/bottom of IP)?

Going to run out and pick up some fuses.
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  #67  
Old 03-04-2018, 11:46:54 PM
TLB01 TLB01 is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

Lever is a primer. Like a primer bulb.

Not stay running how? Does the starter crank, engine fire but when you release the switch to the run position does it just die? As in the fuel solenoid goes back to the shut off position? Or is it fuel starving?

This is the set up I have:
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  #68  
Old 03-04-2018, 11:54:55 PM
DieselBound DieselBound is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

Nice setup!

Of late it was dying when I let off the switch. But, I could not tell for sure if I was getting the air out of the fuel, so I kept on cranking it (allowing some time between cranks).

In the past it started dying on me after about 10 minutes or so. That was due to air incursion. I'd pump the in-line primer bulb (kind that's used in the boating world- that's how it came to me) and it would pick back up and continue to run (after stumbling). I replaced the fuel lines and that add-on primer bulb.

Curious, if that lever is also a primer (I was kind of thinking it was), how does one know when it has successfully primed the IP?

Picked up fuses. I'll poke around more tomorrow.
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  #69  
Old 03-05-2018, 12:00:37 AM
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Default Re: Onan 7.5DKDFL - A good fit for me?

Any particular flavor of smoke coming out of the exhaust before it dies? White? Black? Grey?

As far as the primer leveler, IDK how much is enough. Honest guess is you should not really have to even use it unless its been sitting forever. Its not really to prime the IP but it could if you pump it a 100 times. Its job is just to get some fuel in the LP fuel pump itself so it doesn't just sit and cavitate. Once that LP pump is pushing diesel to the IP, than everything just does its thing. Another member has a DKD out of a light plant with the mechanical pump so he might have more insight.

I have an electric pump. After it runs for a while you can hear the fuel going back into the tank return if the engine is not running.

Last edited by TLB01; 03-05-2018 at 12:13:20 AM.
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Old 03-05-2018, 12:37:43 AM
DieselBound DieselBound is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

White-ish smoke. Insufficient fuel (too much air).

It's a newer battle in that it kind of came on suddenly while I was checking the voltage regulator. In the midst of that testing the starting problems cropped up (though I cannot be certain that it's the result of those tests). I wanted to make sure that I didn't have any water in my fuel; this may have reintroduced air problems, I don't know because I really haven't been able to crank all that much. One thing that's really nagging me is that when it cranks it's not very fast; occasionally it'll kind of speed up cranking speed, but mostly it struggles. I've got multiple batteries, even jumpering with additional batteries. Seems to be pulling the battery/batteries down pretty quickly. It's never been a real fast spinner: I have thoughts about pulling the starter, cleaning it up and giving it a little grease- maybe the brushes are messed up? (I'm kind of over quota on starter work of late, having rebuilt a spare starter for my cars and cleaning and replacing brushes for the starter in my Polaris.) I cleaned up a couple more grounds; I don't expect this to make any difference as they didn't look bad, but I did it just to rule out.

The issues have multiplied.
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