ProSoundWeb Community

Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB: The Classic Live Audio Board => Topic started by: Dave Guilford on June 22, 2021, 09:45:11 AM

Title: Multiquip generators - runs until loaded
Post by: Dave Guilford on June 22, 2021, 09:45:11 AM
Just curious if any of you folks are pros when it comes to this. I have an old 7000w MultiQuip.  Runs fine and great for hours.  Once I put a load on it, I get about 5-10 mins before it shuts off.  None of the lights are on, and it doesnít flip the breaker. The engine just stops running. I can start it right back up, but once there is a load on it again I only get five or 10 minutes.

Quite embarrassing. 

Itís going to my car mechanic tomorrow. I will have them do you oil change, all filters and pumps. Just wondering if thereís anything else I may be overlooking? I donít think itís the engine because otherwise it would shut down during the hour that I let it run without load .. right? 

What part of the power generator would cause the engine to shut down though?
Title: Re: Multiquip generators - runs until loaded
Post by: Simon Lewis on June 22, 2021, 09:58:21 AM
What part of the power generator would cause the engine to shut down though?
Restricted fuel lines or blocked carburetor is one possibility....
Title: Re: Multiquip generators - runs until loaded
Post by: Dave Garoutte on June 22, 2021, 12:29:57 PM
Restricted fuel lines or blocked carburetor is one possibility....
Piston seizing due to lack of oil.
Title: Re: Multiquip generators - runs until loaded
Post by: Chris Hindle on June 22, 2021, 12:45:18 PM
Just curious if any of you folks are pros when it comes to this. I have an old 7000w MultiQuip.  Runs fine and great for hours.  Once I put a load on it, I get about 5-10 mins before it shuts off.  None of the lights are on, and it doesnít flip the breaker. The engine just stops running. I can start it right back up, but once there is a load on it again I only get five or 10 minutes.

Quite embarrassing. 

Itís going to my car mechanic tomorrow. I will have them do you oil change, all filters and pumps. Just wondering if thereís anything else I may be overlooking? I donít think itís the engine because otherwise it would shut down during the hour that I let it run without load .. right? 

What part of the power generator would cause the engine to shut down though?
Start with the fuel filter........
Is it gravity fed? Look for crap in the tank near the fuel outlet.
While you're at it, check the Air Filter too.
Chris.
Title: Re: Multiquip generators - runs until loaded
Post by: Chris Hindle on June 22, 2021, 12:55:57 PM
Piston seizing due to lack of oil.
If a piston were to seize, it would NOT start up right away.
95% sure it's a fuel and/or air problem.
Chris
Title: Re: Multiquip generators - runs until loaded
Post by: Kevin Maxwell on June 22, 2021, 06:03:43 PM
If a piston were to seize, it would NOT start up right away.
95% sure it's a fuel and/or air problem.
Chris

Bad gas? Sat too long with no gas stabilizer in it? Also bad plugs can exhibit that behavior. I had to move up to a hotter plug on one of my motorcycles because it wasn't running right. 
Title: Re: Multiquip generators - runs until loaded
Post by: Mike Caldwell on June 22, 2021, 09:04:25 PM
Hows does the engine die, starts sputtering and coughing and then quits or quick just like you turned off the ignition.

Just to check is this gas or diesel?

Title: Re: Multiquip generators - runs until loaded
Post by: Dave Guilford on June 22, 2021, 10:31:27 PM
Excellent questions.  Answers here..

Fuel filter. I donít know if itís gravity fed. I know thereís a fuel pump, but Iím clueless enough to not know if thatís relevant lol

Last time it was serviced was October 2020 (only 7 months ago).  The dude literally emptied the fuel tank and said it was full of sludge and crud. I bought it used 3 years ago, and it had seen a lot back then, so no surprise .. just a learning experience.  After that cleaning, I filled it up and it ran a full tank with no problems.

After that, it sat for the winter, virtually empty of fuel.   3 weeks ago I pulled it out of storage, filled it up, and ran 6 hour show on it.  Did another 6 hour show  again the next week (same tank of fuel). This past week it kept shutting down as I described.

Itís diesel yes.

As for how it shuts down, I didnít think to notice , but Iím leaning towards cut ignition and not sputtery and wheezy.  If it happens again Iíll be sure to tune in.
Title: Re: Multiquip generators - runs until loaded
Post by: Chris Hindle on June 22, 2021, 11:59:08 PM
Excellent questions.  Answers here..

Fuel filter. I donít know if itís gravity fed. I know thereís a fuel pump, but Iím clueless enough to not know if thatís relevant lol

Last time it was serviced was October 2020 (only 7 months ago).  The dude literally emptied the fuel tank and said it was full of sludge and crud. I bought it used 3 years ago, and it had seen a lot back then, so no surprise .. just a learning experience.  After that cleaning, I filled it up and it ran a full tank with no problems.

After that, it sat for the winter, virtually empty of fuel.   3 weeks ago I pulled it out of storage, filled it up, and ran 6 hour show on it.  Did another 6 hour show  again the next week (same tank of fuel). This past week it kept shutting down as I described.

Itís diesel yes.

As for how it shuts down, I didnít think to notice , but Iím leaning towards cut ignition and not sputtery and wheezy.  If it happens again Iíll be sure to tune in.

Diesel has a fuel pump, no question.
You have Glow Plugs to preheat the combustion chambers, not Spark Plugs to ignite the fuel.
It is a compression ignition engine. Electric has nothing to do with your problem.
It is a fuel problem. Probably not enough volume/pressure once the motor is under load.
Chris.
Title: Re: Multiquip generators - runs until loaded
Post by: Kevin Maxwell on June 23, 2021, 12:11:07 AM
Plug in a couple of old style theatrical lights 500w or more after you have stated it up and see if it keeps running or shuts down.
Title: Re: Multiquip generators - runs until loaded
Post by: Tim McCulloch on June 23, 2021, 12:36:20 AM
Diesel?  Replace the fuel filter(s).  Pre-fill with fuel if possible.  Treat fuel in tank with a diesel biocide.
Title: Re: Multiquip generators - runs until loaded
Post by: Mike Caldwell on June 23, 2021, 07:40:43 AM
Diesel has a fuel pump, no question.
You have Glow Plugs to preheat the combustion chambers, not Spark Plugs to ignite the fuel.
It is a compression ignition engine. Electric has nothing to do with your problem.
It is a fuel problem. Probably not enough volume/pressure once the motor is under load.
Chris.

At least one high pressure fuel/injector pump and maybe a pump before the injector pump. 
There will be cut off valve in the fuel line at some point as well.
Title: Re: Multiquip generators - runs until loaded
Post by: Chris Hindle on June 23, 2021, 08:16:06 AM
At least one high pressure fuel/injector pump and maybe a pump before the injector pump. 
There will be cut off valve in the fuel line at some point as well.
I worked in automotive, not Genny's, but a diesel is a diesel.
Medium pressure, high volume pump in the tank, with the (high pressure, low volume) Injection Pump/distributer at the motor.
Saw many occasions where the engine would start, and stall when dropped in gear. A simple gauge  on the inlet of the injector pump showed not enough fuel being drawn from the tank.
I suspect that is the problem here.
Blocked filters are the first place to look, of course.
A diesel not run often is an unhappy diesel........
Chris.
Title: Re: Multiquip generators - runs until loaded
Post by: Mike Pyle on June 23, 2021, 11:53:51 AM
Many gen sets are equipped with automatic and remote start/stop relays incorporated into the regulator panel. There could also be shutdown relays for engine fault conditions (low oil pressure, overheating, etc). You need to determine first if the fuel system is being shut down by one of these control mechanisms, or by a mechanical issue with the governor or linkage, or by fuel supply problems as others mentioned. Systems may use solenoids connected to mechanical linkage, or to a fuel shutoff valve.
Title: Re: Multiquip generators - runs until loaded
Post by: Steve-White on June 30, 2021, 05:21:22 PM
Restricted fuel lines or blocked carburetor is one possibility....

Yep.  Carb hosed, fuel filter clogged up or moisture in tank - or all of the above.

Put a can of Berryman's or Sea Foam in it and run the tank empty with whatever load it will handle.  Change fuel filter, clean or replace oil filter.

When test running a generator always run it steady stare with 25-50% load and a few good pulls at full load.  Full load testing is the only way to know if they are working correctly.

Also check the oil level in the crank case, and the low oil sensor if it has one.

Or, simply take it to your mechanic and let him do it.