Fussy ISM Cold Start

Topic: Fussy ISM Cold Start (Read 1604 times) previous topic - next topic

Fussy ISM Cold Start

January 16, 2021, 04:45:46 pm

Hello all,
I'm looking for some suggestions. This coach has ALWAYS been this way and it has never really gotten worse. Here are the symptoms:
When it is cool outside, say anything around 45F and below, the coach doesn't want to start. Originally this was attributed to the 4d start battery. I replaced this with 3 proper spec optima red tops. Now it cranked a lot faster.
Eventually I had further issues so I replaced the starter with the geared starter. Now the coach cranks very quickly. I foolishly thought my issue was solved as after that it always started within 5 seconds or so.
I've lived in Florida now for years so I haven't had any colder temperatures but today was a little cooler and the engine was showing 50F so I decided to try to start it. Wasn't happening.

So I did some experimenting. Looked for codes with VMSpc. Nothing. Checked for oil pressure. It got up to 17psi under cranking so that would be fine. I really don't know how long you can crank for without damaging the starter so I only did maybe 10 seconds max. Typically whenever I would hear the starter start to slow down a tiny bit I would stop and then let the battery recharge.
This went on for about 30 minutes with about 6 or 7 crank cycles. At this point I cranked and let it crank a little longer, probably closer to 15 seconds and with a quick puff of black smoke it roared to life.

So... it's not like an old school diesel cold start... like the videos you can find on youtube. First it's not actually that cold! Secondly there is no smoke. There is no single cylinder firing. It is just DEAD and then all the sudden like a light switch all cylinders fire and it roars to life (with enthusiasm). So it's like the ECM isn't allowing it to fire. But I can't think of what could be wrong. Any ideas?

If it helps I noticed that if you for some reason crank the first time around and stop cranking before it starts, it's always going to be harder to start when you try again. Warm starts are never hard.

Thanks!

Re: Fussy ISM Cold Start

Reply #1 – January 16, 2021, 05:27:58 pm

My M11 starts fine to a least 30 degrees and when it gets colder if it doesn't start I give it a shot of ether or warm up the engine.
At 40 degrees you should not have any trouble. You could check out the speed sensor, the ECU won't let the engine start until it
reads the engine turning over.

Re: Fussy ISM Cold Start

Reply #2 – January 16, 2021, 06:39:30 pm

M-11's don't have intake heaters they do have the ether button if really cold.

Re: Fussy ISM Cold Start

Reply #3 – January 16, 2021, 07:08:57 pm

Quote from: craneman – January 16, 2021, 06:39:30 pm

M-11's don't have intake heaters they do have the ether button if really cold.

That's the reason you can use ether in the intake. Not a good idea if it has a heated screen.

Hard starting in cold weather can be summer diesel, tight intake valves, a little air getting in the fuel system, return fuel valve (back to the fuel tank) leaking letting system pressure drop to zero.

Pierce

Re: Fussy ISM Cold Start

Reply #4 – January 16, 2021, 07:44:08 pm

Sure sounds like one of the engine sensors isn't giving the permissive to the ECM and all of a sudden it wakes up. If you find oil soaked area around the cam/speed sensor it may be failing as has been mentioned. While there if this area is oily look for an oil pressure sender mounted just below it hid kind of behind the fuel pump. Some of the M-11 oil pressure senders are hid there. If it is oil soaked change it out while there.

Mike

Re: Fussy ISM Cold Start

Reply #5 – January 16, 2021, 07:52:55 pm

Quote from: Pamela & Mike – January 16, 2021, 07:44:08 pm

Sure sounds like one of the engine sensors isn't giving the permissive to the ECM and all of a sudden it wakes up. If you find oil soaked area around the cam/speed sensor it may be failing as has been mentioned. While there if this area is oily look for an oil pressure sender mounted just below it hid kind of behind the fuel pump. Some of the M-11 oil pressure senders are hid there. If it is oil soaked change it out while there.

Mike

I will check those out. Does it have a dummy on/off sender that it uses for oil pressure? Reason I ask is because the oil pressure psi reading looks good during cranking.

In retrospect I didn't actually look at what the tach reading in vmspc was. You'd think you wouldn't get a tach reading during cranking if the speed sensor was failing. But I read that the speed sensor has redundant loops and it will crank extra long if only one of them is working. You'd think it'd throw a code though.

The return valve is high on my list of suspects. I am looking at getting cummins insite/inline but I'm seeing you can check fuel pressure on the side of the pump.

The thing is, it really feels like the ecm is preventing startup until some condition is satisfied. Like it *really* feels like that. It runs perfectly once it starts. Most reports of return valve issues involve stalling after starting as well.

Re: Fussy ISM Cold Start

Reply #6 – January 16, 2021, 07:59:26 pm

Old failing fuel lines could be part of the issue

Re: Fussy ISM Cold Start

Reply #7 – January 16, 2021, 08:17:22 pm

There was a hard start tsb that I had Cummins do on my coach a while ago.

Re: Fussy ISM Cold Start

Reply #8 – January 16, 2021, 08:20:17 pm

I understand Cummins has several fimware updates for the ECU that relate to slow start. Has your electronic engine been updated in firmware? Might be a good place to start.

Re: Fussy ISM Cold Start

Reply #9 – January 16, 2021, 08:28:23 pm

Quote from: Mark D – January 16, 2021, 07:52:55 pm

1. Does it have a dummy on/off sender that it uses for oil pressure? Reason I ask is because the oil pressure psi reading looks good during cranking.
2. But I read that the speed sensor has redundant loops and it will crank extra long if only one of them is working.
2a.You'd think it'd throw a code though.
3. The return valve is high on my list of suspects. I am looking at getting cummins insite/inline but I'm seeing you can check fuel pressure on the side of the pump.

Mark,

1. On some years or some coaches Foretravel installed a oil pressure sender for the dash gauge in one of the oil ports that are on the oil cooler side of the engine. If yours is one of these then that is where the dash would getting it's signal. you would just have to snoop around.
2. Correct
2a. Not always
3. I bet if it was this it would run like azz.
3a. If you are going to be working around on the pump you might as well pull the little fuel filter on the pump (yep there is one there) and replace it while you are running fuel pressure test.

There was a hard start update for the ECM long ago but that should have already been done with the age of your coach. While I was typing this 2 others posted this also.

Mike

Re: Fussy ISM Cold Start

Reply #10 – January 16, 2021, 08:34:48 pm

Mark,

Read through this thread as to the filter on your pump. I figured you would ask. Fuel pump leak 99 M11

Mike

Re: Fussy ISM Cold Start

Reply #11 – January 16, 2021, 08:50:58 pm

I don't know if you are supposed to do this or not but mine cranked a bit longer than norml once or twice and I gave it just a bit of throttle and it started right away.

The geared starter probably turns about as fast as the non geared one i think the gearing makes the motor turn a bit slower with less battery effort.

Preheat engine with AH it is below 40°. Easy on engine and batteries.

Re: Fussy ISM Cold Start

Reply #12 – January 16, 2021, 09:29:08 pm

When I said warm up the engine I meant Aqua-hot or block heater and then no ether.

Re: Fussy ISM Cold Start

Reply #13 – January 16, 2021, 10:51:31 pm

I would never use ether on an engine I care about. I did actually use the AH preheat as I was starting to get a little desperate. The coolant temp was 75F when it finally started.

Thanks for the suggestions. I will check them out!

Re: Fussy ISM Cold Start

Reply #14 – January 16, 2021, 10:56:41 pm

Quote from: Chuck Pearson – January 16, 2021, 08:20:17 pm

I understand Cummins has several fimware updates for the ECU that relate to slow start. Has your electronic engine been updated in firmware? Might be a good place to start.

Mine saw a cummins dealer when we bought the coach in late 2013 for a dyno test. However I didn't ask for a firmware update. It's quite possible it has never been done. The dyno sheet had a lot of data about the ecu so I should be able to figure out what the version is from there and figure out if I have the update.

Re: Fussy ISM Cold Start

Reply #15 – January 17, 2021, 09:55:44 am

Question: I am going for an early am start, with little time for AH engine heat. Is there any problem with turning the engine heat on the night before, and have it on for 8 hours or so.
Thanks, Mike

Re: Fussy ISM Cold Start

Reply #16 – January 17, 2021, 09:58:30 am

The ISM firmware update is not something Cummins would perform automatically as it takes time/$....not a freebie.

I had my ISM ECU updated at Cummins Coach Care last year from the original firmware that was in the ECU when I bought it. It took several hours as it involved multiple updates that had to be done on top of the older ones.

Noticeable improvements: cold starts are definitely more expedient, especially with battery boost (guessing a lower threshold for oil pressure before injectors come alive?), less turbo lag, and a simple but convenient plus...cruise control speed is retained even after engine shut down.

Well worth the time and $ for me anyway.

Re: Fussy ISM Cold Start

Reply #17 – January 17, 2021, 09:59:32 am

Mike no problem with turning the block heater on the night before.

Re: Fussy ISM Cold Start

Reply #18 – January 17, 2021, 10:28:19 am

The hard start issue is adjusted by when they fire in the fuel vs the number of rotations heat build up etc. They told me it would make a big improvement and it did.
Well worth the time and $ for me anyway.

Re: Fussy ISM Cold Start

Reply #19 – January 17, 2021, 10:48:57 am

Mike. I do believe that my coach starts better since I changed fuel lines. Prior the fuel in the plastic screen almost looked foamy. Now it looks like moving fuel but few bubbles. I had to change my blue speed sensor in June when I purchased the non-running coach and thanks to the forum I had a spare with me. Since fuel line change coach has started during colder weather, but I know it has its limits that I don't hands on know yet what they are. 35 degrees and what seems like two full revolutions and fires right up. This was a cold soaked engine start with No additional preheat or starting aids. Like yours zero tailpipe fumes/smoke prior to light off.
Scott

Re: Fussy ISM Cold Start

Reply #20 – January 17, 2021, 11:05:33 am

Quote from: Yetch – January 17, 2021, 09:55:44 am

Question: I am going for an early am start, with little time for AH engine heat. Is there any problem with turning the engine heat on the night before, and have it on for 8 hours or so.
Thanks, Mike

Re: Fussy ISM Cold Start

Reply #21 – January 17, 2021, 11:09:10 am

Sorry Mike I'm not used to quoting, it won't hurt to have the Aqua-hot on all night or as Bruce said the block heater.

Re: Fussy ISM Cold Start

Reply #22 – January 17, 2021, 02:33:46 pm

Reliable Diesel Starting Fluid Never Leaves You Out In The Cold | PTI

Says there is a thermostat and is metered per Cummins manual, conflicting it says not to use more than five seconds. Foretravel manual say to use. Does not mention temp range lockout

Re: Fussy ISM Cold Start

Reply #23 – January 17, 2021, 02:51:23 pm

It does have a temp lockout. Follow the wires from the start unit and you can see the sensor on the engine I don't know how cold it has to be to allow the ether but it is below 40 deg. that was the temp when I was trouble shooting it to make sure it worked. I unhooked the ether line and bypassed the sensor and had my son push the ether button and it worked. Hooked it all back up and have never needed it yet.

Re: Fussy ISM Cold Start

Reply #24 – January 24, 2021, 03:59:00 pm

Tried to use the ether start last Friday and it wasn't working. Went out with my son this morning, took the hose off the intake
manifold and tried it. No ether, told him to do it a few times still nothing and then said to hold it, still nothing. Started to put the
hose back on and said let go of the switch, ether came out. Told him to push it again, nothing said let go of the switch, ether
came out. The ether comes out when the switch is let go so it is metered. It took a few times of off and on to fill the hose with ether.

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