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Topic: Engine cuts out when using the microwave (Read 526 times) previous topic - next topic

Engine cuts out when using the microwave

Why would the engine want to stall out while using the microwave while driving?
This is a new development, if we start the generator everything is fine.
Voltage from the alternator (measured at the isolator) 14v
Both battery banks fully charged.
Boost switch off.
Ideas?

Thanks
Frank
Frank & Connie Williams
1999 U320 '36
Build: 5466
MC: 18335

Re: Engine cuts out when using the microwave

Reply #1 –
Frank,

Now that is a first for me but here is a couple of thoughts.  It could be caused by a voltage drop below about 9 volts DC (as that is about the lowest voltage the ECM will function) on the engine batteries momentarily. Now the big question is why would the voltage on the crank batteries drop when the micro is on the coach batteries? It could be a bad isolator or voltage sensing relay (if the isolator has been changed out) or the boost relay causing the hole system to be one battery. Really this area is the only place the 2 battery systems come in contact with each other. If this is the case look at the battery cables for a good connection. Check the sense wire for the alternator along with the breaker for good connection. Check boost relay, isolator (or VSR), battery connections. I am verry interested in finding out the root cause as I ain't got much hair left to pull out.

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Engine cuts out when using the microwave

Reply #2 –
If voltage drop is not the issue (unlikely, as chassis battery does not power the inverter), MAY BE (ya, capital MAY BE) Electromagnetic waves affecting ECU.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Engine cuts out when using the microwave

Reply #3 –
Can you duplicate the error while sitting still with engine on and microwave on? 
Jerre and Kathy Griffin
2003 U320 4220 Special
Build # 6207
2022 RAM Laramie 4X4 EcoDiesel
2002 Country Coach Magna 37 Tag- Forever Coach-Died in fire 7/23
1997 Country Coach 32 Intrigue-No slides-Wonderful

Re: Engine cuts out when using the microwave

Reply #4 –
Mike, I'll check the isolator by disconnecting the house batteries from it and try again.

Brett, that's way over my head... LOL

Jerre, yes, that's how I'm T/S it in the driveway.

I'll be back!
Frank & Connie Williams
1999 U320 '36
Build: 5466
MC: 18335

Re: Engine cuts out when using the microwave

Reply #5 –
Removed the house batteries from the isolator and that isolated the problem down to the...isolator.
Ran the microwave several times, 30 seconds each, no issues.
Had one fail before on our other coach and it just stopped working, this was strange for sure.

Thanks guys

Decision time now.
Frank & Connie Williams
1999 U320 '36
Build: 5466
MC: 18335

Re: Engine cuts out when using the microwave

Reply #6 –
Quote from: wolfe10 –
If voltage drop is not the issue (unlikely, as chassis battery does not power the inverter), MAY BE (ya, capital MAY BE) Electromagnetic waves affecting ECU.

If that was the case, the microwave is operating way, WAY out of spec.  That's a huge distance for them to travel unless someone had seriously borked with the Faraday cage.
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Engine cuts out when using the microwave

Reply #7 –
Problem is NOT there when generator is running per Phranko.

So could be inverter screwing with chassis voltage.  Maybe bad grounds somewhere. Or boost switch stuck on.
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: Engine cuts out when using the microwave

Reply #8 –
If the OP has an M11 in his U320, I can not see how an overloaded alternator could stall an Engine with that much torque. 🤷‍♂️
Doesn't sound logical.
Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota

Re: Engine cuts out when using the microwave

Reply #9 –
Quote from: Phranko –
Removed the house batteries from the isolator and that isolated the problem down to the...isolator.
Ran the microwave several times, 30 seconds each, no issues.
Had one fail before on our other coach and it just stopped working, this was strange for sure.

Thanks guys

Decision time now.
Does your battery voltage drop when the microwave kicks in? I don't think it's putting too much of a load on the engine,  but I bet the voltage is dropping. 

Victron Energy Argofet Battery... Amazon.com: Victron Energy Argofet Battery Isolators 200-2AC (2 Batteries...

I put one of these in and it's working great.
As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.
1991 U300 Side Aisle 6V92 Silver #3897
2004 U320 40' #6246

Re: Engine cuts out when using the microwave

Reply #10 –
After some guidance from the forum the house batteries were disconnected from the isolator, problem cleared.
Several options at this point and seeing what others have done is food for thought.
Frank & Connie Williams
1999 U320 '36
Build: 5466
MC: 18335

Re: Engine cuts out when using the microwave

Reply #11 –
The Victron ArgoFET isolator (Reply #9 above) is a excellent unit.  I used one for a while...until I decided I could get along fine without any isolator.  See post linked below.

Just another path for your consideration.

Delco Remy 28SI Alternator Installation

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Engine cuts out when using the microwave

Reply #12 –

This is what I use for an isolator now. Another option.
Amazon.com: Blue Sea Systems 7700 SOLENOID ML 12V RBS : Industrial & Scientific

If you had revved up the engine the alternator should have kept up with the microwave consumption, but
you wouldn't have known you had a bad isolator.

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport
 

Re: Engine cuts out when using the microwave

Reply #13 –
[An unhelpful, off-topic response has been deleted.  moderator Michelle
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320