Generator Cold Start Issue

Topic: Generator Cold Start Issue (Read 1656 times) previous topic - next topic

Generator Cold Start Issue

April 27, 2012, 09:18:54 am

I've got the Isuzu 3 cylinder. It's been running fine until a few days ago. We're in Nevada and the temps are mild (50s when running genny) I pressed the start button and it did its usual 8 or 10 seconds of clicking but instead of starting right up, it coughed and stumbled, all the while belching out white smoke. (Fortunately, the little state park we're in is almost empty) Anyhow, after maybe 90 seconds or a couple of minutes it smoothed out and ran fine for a few hours. Next day, same thing.

I have 12 volts at the glow plug wire. I had some spare glow plugs so I went ahead and replaced all three. Same issue. I let it run a few hours last night and shut it down. I waited a minute and restarted. Fired right up and ran smoothly.

So.... Stumbling, shuddering and white smoke on cold start and running normally with no smoke when warm. Ideas? Thanks.
jor

Re: Generator Cold Start Issue

Reply #1 – April 27, 2012, 09:51:37 am

Jor,

What's your altitude?

Re: Generator Cold Start Issue

Reply #2 – April 27, 2012, 10:13:25 am

Jor, Check for fuel flow, these things are notorious for fuel lines deteriorating and then either sucking closed or flaking off and trash gets in the filter. Use an outside source of fuel and then see how long it runs.
Gary B

Re: Generator Cold Start Issue

Reply #3 – April 27, 2012, 10:44:04 am

Like Gary said, check for fuel supply problems. If you have replaced the glow plugs, the next thing is an air leak check. Aside from the hoses, check the needle valve (some have it, some don't) shut off for an air leak. Could be a little air leak made worse at higher elevation like Brett said. With altitude, you may have to glow it a bit longer. Also check both fuel filters. Intermittent electrical issue or internal air leak on the lift pump is another possibility.

A Mityvac is a good diagnostic tool. You can isolate different parts of the fuel system and remove possibilities one by one. Using a Vicegrip, you can squeeze off the supply line leading from the tank to check for air leaks on the generator side. Only takes a tiny leak to let air in overnight.

Pierce

Re: Generator Cold Start Issue

Reply #4 – April 27, 2012, 10:59:23 am

Question: Isn't white smoke incomplete combustion?

Re: Generator Cold Start Issue

Reply #5 – April 27, 2012, 11:09:14 am

Sounds like a glow plug issue to me, DO NOT USE EITHER.
Glow plugs come in 6 or 12 volt models, normal 6 volt are on for a few seconds with 12 volt supply, it they are the 12 volt glow plugs, you will need about 45 to 60 seconds of heating.
Dave M

Re: Generator Cold Start Issue

Reply #6 – April 27, 2012, 11:13:51 am

Dave,
How do you get more glow plug time. Can you just hold the rocker switch down? I thought it was strictly auto.
jor

Re: Generator Cold Start Issue

Reply #7 – April 27, 2012, 11:21:37 am

Just noticed. I replied to several posts with one reply but it didn't post. Real iffy cell connection here (no phone but some data). Let's see...

We're at 7300 feet. What's the deal? I thought that deisel performance was little affected by altitude.

I've replaced supply and return fuel lines and the several up front lines too.

I've replaced my one fuel filter (large canister) and don't have a second filter (no inline anyhow).

I'll try that separate fuel source when I can.

Hope this one posts!
jor

Re: Generator Cold Start Issue

Reply #8 – April 27, 2012, 11:32:10 am

Not easy to change the glow lug heat time, I would leave that alone and get into the glow plugs, check the specs by the number on the glow plug and the data sheet for it, make sure it is a 6 volt model.
Also dont try to remove the glow plug and use a plug, that cylinder will not fire without a glow plug.
Meaning glow plugs are needed to run the engine, not just start it.
When running the combustion will keep it hot.
Dave M

Re: Generator Cold Start Issue

Reply #9 – April 27, 2012, 11:33:37 am

Also, Pierce, what's the deal with the needle valve? Is this like a carb needle and seat? Also, not sure what you mean with the vice grips on the supply line? Thanks.
jor

Re: Generator Cold Start Issue

Reply #10 – April 27, 2012, 11:40:00 am

Plug number is NGK 6926 Y-106V. I'll check now on the voltage rating if my Internet connection holds up.
jor

Re: Generator Cold Start Issue

Reply #11 – April 27, 2012, 11:45:01 am

IF they are 6 volt, I would use a ohm meter and verify the element is there.
Dave M

Re: Generator Cold Start Issue

Reply #12 – April 27, 2012, 12:03:11 pm

I'm confused on the 6v rating, Dave. The NGK site has a number decoder for their glow plugs. They list only 12 and 24v ratings - no 6v. Mine, for example, decode to a 10mm thread, 12 volts and "rapid rise" temp.
jor

Re: Generator Cold Start Issue

Reply #13 – April 27, 2012, 12:16:50 pm

Anyone know the proper glow plug number for my Isuzu? I bought the number listed on Barry's site, think I got the right ones but I note the ones I removed are a different number. The engine is:

Isuzu. 3LD1

Re: Generator Cold Start Issue

Reply #14 – April 27, 2012, 12:33:13 pm

Forgot to say that when replacing fuel hoses, always use the special fuel injection type clamps at all hose ends. They squeeze ALL the way around the fuel line and seal much better than the little stainless clamps you get at the auto parts or hardware store. They will have the correct type but you have to ask for them. If you use a very slightly larger replacement hose, the conventional clamps may leak a little air. A little hard to explain but here is close to what they look like: BusDepot.com - VW Bus / Camper / Vanagon / EuroVan Specialists
I like the German OE style the best with no sharp edges and a philips screw to tighten. They just look more professional. Seems like a little thing but the small details pay off.

OK, the vice grips: If you use a Mityvac, you can't seal the end of the supply hose that goes into the tank to check for leaks with a vacuum gauge (Mityvac) without getting to the hard to reach end. I just squeeze it part way to the fuel tank so I can check for leaks where it reaches the generator. I still can't check the hose right at the tank but can eliminate all the other possibilities. Remember, there are two fuel lines, a supply line that goes to the pump, etc. and a return line that returns excess fuel back to the tank.

On Bosch pumps, there is also a small check valve (a ball with a spring on it) to keep the low pressure fuel in the pump at prescribed pressure. I have seen algae or other crud coat the ball so it leaks some of the fuel back into the tank return line. It's usually on the back of the pump next to the block and has a fuel line coming out of it. We always replaced it when recalibrating the pumps for the turbos.

Many of our generators have a needle valve shut off close to the high pressure injection pump. You can see it when you open the compartment door. Mine has one but I noticed Bill Chaplin's did not. Same year, same generator. If they leak, they drip down onto the engine mount below like mine did. You can use a small open end or crescent wrench to tighten the nut the needle goes through just slightly to seal and stop any leak.

Dave has excellent advice. Double check the glow plugs are working and the correct type. Working with the old style glow plugs, they would take 30 seconds or longer to glow enough to start in cold weather. With the new "rapid rise" plugs, my 440K mile Mercedes diesel only needs to glow 3 to 5 seconds in freezing weather to give an instant start.

Keep in touch and the forum will get you started. :-)

Pierce

Re: Generator Cold Start Issue

Reply #15 – April 27, 2012, 08:28:47 pm

I have a 3LB1. I live at 8,000 feet. Every generator start has white smoke for at least 30 seconds. I heat with my glow plugs twice: count to 12 with the button on (watching the voltage indicated in the little TV go down) wait for 10 or 12 off, then again for 12 seconds on, then start, then watch the gray/grey smoke until it hits on all 3 cylinders and runs smoothly. I don't think you have a fuel problem because you stated that the gen runs.... What you have is a mixture challenge and a non-turbo diesel. It only produces about 60 % of the rated power at 8,000. I can still run two air conditioners but I don't do this until the battery charging is under 50 amps. Last week while in ABQ (lower altitude), no white smoke. Andy

Re: Generator Cold Start Issue

Reply #16 – April 27, 2012, 08:35:03 pm

I also have the Isuzu 3LB1 engine on the 8 Kw genset, but in 9 years it's never smoked at start-up...not even when it was sucking air through the air lines a couple years ago. Perhaps the incomplete burn at start-up is due to the altitude's lower oxygen and the ambient temperatures.

Re: Generator Cold Start Issue

Reply #17 – April 27, 2012, 10:29:25 pm

Lewis, I don't think I can do that 12 second deal,with mine. It's a momentary rocker type switch. You just press it and the sequence begins. Doesn't matter whether you let it go or hold it; it starts clicking and it about 8 seconds the starter kicks it over.

Pierce, I used those good clamps that you have to cut off.

UPDATE: We moved today from 7300 altitude to about 4800. Tried it again with the same result. Sputter, smoke, stutter, kinda start, start. Anyhow, I decided to try something. I held down the start switch for 6 seconds or so and then pressed it again to avoid the start. Did the same thing twice more and on the third time let it start. Vroom... Just like it's supposed to!

So what exactly is happening in the 8 seconds before the starter engages? Am I simply energizing the glow plugs several times and thus providing more pre start heat? Thanks. (probably should be driving a gasser; know a lot more about them!)

Re: Generator Cold Start Issue

Reply #18 – April 27, 2012, 10:48:03 pm

Yes, altitude can have a lot to do with start up smoke. The issue here in not the mixture as there is really no mixture problem but lack of compression heat to ignite the diesel spray when injected along with less oxygen. With pre-combustion chambers and glow plugs, the diesel is sprayed into the chamber and vaporizes when part of the spray hits the hot glow plug. This allows it to explode if there is high enough temperature in the rest of the cylinder. With three cylinders (or four) one bad glow plug or a tight valve (valves need adjusting, have no clearance when cold and reduce compression/heat in the low cylinder) in ONE cylinder can make starting difficult with lots of smoke. Also true with a four cylinder engine. 7700 feet is about the point where an a non-turbo engine only produces 75% power. Turbo engines may be even harder to start as they frequently have lower compression ratios than non-turbo engines so they generate less compression heat when trying to start at any altitude but especially true up at altitude. That's why turbo Detroit Diesels don't start as well in winter as the normal supercharged variety.

In short, high altitude can bring out a weakness in a single area or may show up as a combination not normally seen at lower altitudes and/or warmer temperatures. Starting problem areas may be in one or more of the following areas:

Low compression from ring wear (may be checked with compression gauge)
Low compression from out of adjustment valves (one cylinder may do it)
Lower compression from high altitudes
Dirty injectors with poor spray patterns (the bigger the droplets, the harder it starts, the more it smokes)
One or more faulty glow plugs
Air in system
High altitude with colder morning temperatures. Temperature drops approx. 3.5 degrees per thousand feet increase in altitude.
Bad or partially discharged battery or poor cable connections with resulting slow cranking RPM (the faster the engine cranks, the less loss past the rings so higher combustion pressures/temperatures)
A load of summer diesel at high altitude in winter (summer diesel may be partially mixed with gasoline for easier starting)

Starting diesels has A LOT to do with bringing the combustion chamber temperatures up to a point where the diesel will explode when injected. (and diesel does not burn in the engine, it explodes)

And for Jor's last post (just read it) about the "third time is the charm", yes, you are creating more heat which in turn, allows the diesel to more easily explode and make the transition from the starter motor to self-sustaining combustion/running.

Pierce

Re: Generator Cold Start Issue

Reply #19 – April 27, 2012, 11:26:59 pm

When our generator is cold, we manually pre-heat for a long time, like over a minute before starting. Our dash gen switch is down to preheat or stop and up to crank, so I just hold down the switch longer. One time in freezing temps, I held down the preheat for 3 minutes.

Re: Generator Cold Start Issue

Reply #20 – April 27, 2012, 11:37:31 pm

Jor,
I'm not sure if this will help with your engine, but with my Kubota the folks here at FOT gave me a quick test procedure for the glow plugs. My notes are attached, including some info from Pierce.

Re: Generator Cold Start Issue

Reply #21 – April 27, 2012, 11:51:44 pm

I had the identical problem with my Isuzu powered 10K gen a couple of weeks ago. I live at 4,200' MSL, and my unit has over 4,500 hours on it. Changed the block mounted canister filter and problem remained. Called a friend that is trained diesel mechanic, and he came over and recommended changing the air filter and the in-line cartridge type filter that is located in the bottom of the compartment that you remove the panel to get to when changing the air filter. That cartridge type filter (looks like an in-line filter that was used at the inlet to a lot of carburetors some years ago) screws into what appears to be a low pressure fuel pump. Numbers were unreadable which lead me to believe its been in place a long time. Matched it at NAPA, but don't recall the number. We both believe it may be a pump that brings fuel from the tank and supplies it to the high pressure pumps that are on the engine block. Regardless - no more real problem. Still a little smoke on start up if its set cold for a couple of days, but it now runs smooth and doesn't stumble within a few seconds after startup. Main air filter did not look dirty using a very bright light and that makes me suspicious it was the cartridge filter.

Dan

Re: Generator Cold Start Issue

Reply #22 – April 28, 2012, 11:38:48 am

Thanks to all for your ideas. I'm printing out several for future use. Great info. Here's the latest. As I said yesterday, we're down to 4800 feet from 7300. My three time glow plug deal caused the genny to start properly yesterday. We're staying at a small state park which is mostly tents and small trailers. So this morning I head out with the dog at about 5:30. When I get back THE GENERATOR IS RUNNING! WTH (that's heck)? Apparently, I had left the switch on auto and when my wife turned on the coffee maker (86 amps) the voltage dropped to its usual 11.6 and the auto gen figured it was time to take up the slack. I'm thinking' we're not too popular with our neighbors right now!
jor

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