maxx 470 wont stay running

[Kevin B]

Ok. Here is the deal. I have a hydramaster Maxx 470 that has been fairly trouble free for the last 3 years. Today, we started the machine up, and was idling for a few minutes and when I went to turn up the RPM, the machine just died. I never actually pushed the switch to adjust engine speed. So, I cranked the engine over, it sputtered a bit, and wouldn't start.

To back up some, over the last week or so, the machine has died randomly and started right up.

I have bypassed the fuel shutoff solenoid, just in case it was a shut off sensor or relay. I did this bypass with a "hot" wire right from the battery. I have pulled the fuel line off and it appears to be getting a decent flow of fuel from the fuel pump.

I did pull the shutoff solenoid from the bottom of the bowl on the carborator and reinstalled and the machine actually ran for a few seconds before dying. Could this be some sort of carborator problem, fuel pump problem? Electrical problem that I'm just unaware of? I don't know if the machine has some sort of "kill switch" beyond the fuel solenoid.

Tomorrow morning, I plan on replacing the fuel pump, spark plugs and giving it a shot again. What else should I check? If those things don't work, should I pull the carb and clean it? Engine has 2500 hours on it.

 

[Contemporary Carpet Clean]

check the spark strength or to see if you have a spark....we had a kohler with about the same hours on it have one bad coil...it gave a spark but not a strong enough one! We replaced both as recommended by the mechanic. Carburators today do not have ajustments like old ones (emissions bullshit). Kohler has pins in the carb or something like that, they have orings on them and sometimes the orings go bad. Also check the intake gasket/orings whatever it may have. In combination with the bad coil the intake orings were leaking a little too. Check and or replace your air filter too, we have had those plug up (lots of cotton wood trees around here in early spring/summer) and make the machine die under a load and or run rough and through out lots of black smoke.

 

[Contemporary Carpet Clean]

replace spark plug wires if applicable and distributor cap and rotor if applicable. I am not sure if the 3 cylinder Daihatsu engine has these type of componets but would replace these parts anyway due to age and hours of use. All of these parts seem to wear quicker than on a car due to the extreme heat and moisture of being in a van with reduced air flow.

 

[Kevin B]

How exactly do you check spark strength?

So, in addition to fuel pump

1. Replace cap and rotor
2. Replace spark plugs
3. Clean carborator if none of that works
4. Check compression from there

I can replace the air filter, but my presumption would be the machine would still start but probably smoke and bog down easily.

 

[Kevin B]

How exactly do you check spark strength?

So, in addition to fuel pump

1. Replace cap and rotor
2. Replace spark plugs
3. Clean carborator if none of that works
4. Check compression from there

I can replace the air filter, but my presumption would be the machine would still start but probably smoke and bog down easily.

 

[Contemporary Carpet Clean]

go to auto store and tell them you want a spark tester. It looks like a spark plug wire on one end that has a boot plugs into nipple on top of spark plug.....and the other end has a nipple (like on the top of the spark plug) that attaches to the spark plug wire boot. In the middle there is a "light bulb" that lights up when the engine cranks and or runs. If the light looks duller on one cylinder than all the others than you might have a bad coil on that cylinder. You must try the tester on each and every cylinder.


if this is beyond your mechanical ability....take it to a Lawn Mower/small engine repair shop!!!! not a truckmount dealer....We have a small engine repair guy that is amazing (way more experienced with small engines than a truckmount mechanic will ever be) on all these truckmount/lawnmover engines

 

[Zee]

Do not replace the fuel pump just yet.

I had a similar problem with my truckmount, it kept shutting off.

I checked everything-fuel filter, fuel flow, air filter, waste tank float shut off...etc..

It sometimes would run for a minute or two and sometimes would not even start up. Sometimes it would run for 10minutes....

I accidentally moved a bunch of wires that are going down on the frame frome the front panel, and noticed that there is a tiny ground wire cracked away from its base that is being held down by a small screw/bolt.

As I moved the thing it would run the fuel pump right away!

The whole thing was annoying me for days I even had to bring in another truckmount to finish a job and it was a 5cent part that was the cause!!!

The only reason I didn't replace the fuel pump was that the parts store didn't have one that fit my needs.... Save about $120.00 on that.

 

[Captain Morgan]

Had similar problems with my Powermatic w/23hp Kohler. It would run fine, go to cleaning and it run for about 30 minutes then die and not restart. Bring it to my small engine repairman and it would run fine. Go back to job to finish, run for 30 minutes, die and not restart.

My machine is old, mostly original parts. Over the spring and summer I've replaced the starter, throttle body. Those just wore out with age. The stalling issue was separate. I replaced the coil and condenser thinking those were breaking down. Still had the same periodic problems and was getting worse.

Spoke with Steamway distributor and he suggested I check a bunch of things but especially my ignition switch. Took a peek at that and it was flopping around it was so loose. Vibration over the years had worn it out. Replaced that and so far so good.

My mechanic mentioned he's been seeing a lot of issues with ethenol blended gas. It eats rubber, separates in boat, snowmobile, 4 wheeler tanks that sit for a week or two. The alcohol settles to the bottom of the tank and when the engine is started up it's running on pure alcohol and burns up the engine. Probably not our issue because we are using our machines regularly but if the government switches to mandatory E85 then we might see problems with our engines.

Good luck, I feel your pain
Bill

 

[Kevin B]

Yah, I replaced the ignition switch. I pulled the plugs this morning, guys in the process of putting new ones in and we will check the spark. The plugs smelled like gas, which could be an indicication that there is no juice going to the plugs. Possible some bad coils, or worse case scenario the unit that sends juice to the coils. No idea how that works, but I'm pretty mechanical, so I'm sure I can trace it down!

 

[steve frasier]

is there any red lights on, there is always the oil pressure sensor.

 

[The Magician]

Call Hydramster. they will help you. Also check your motor manuel.

 

[alazo1]

I had my maxx 470 shut down on me too. Both wires for the fuel pump are wired directly to the bar off the waste tank. It doesn't shut off any more.

Albert

 

[Kevin B]

The Maxx 470, stupidly so, was not equipped with an oil pressure kill as part of the engine kill relay system(dumb dumb dumb...tisk tisk hydra master. If anyone can tell me how to install one, I will add it to the relay). However, I maintain my equipment very meticulously and don't ever even start a machine without first checking engine oil.

The oil level is adequate.

Here is an update.

I replaced all spark plugs.

Replaced airfilter (was fairly clean since last service)

Pulled carb, there was definitely fuel in the intake and cleaned carb. No blockages at all. All parts appear in good condition with no tarnishing at all.

Checked spark to each cylinder (jumped the tester window very well and very robustly on each cylinder)
Pulled valve cover and all valves appear to travel smoothly. Gaps even looked good since last setting this winter.

I believe we have determined it to be some sort of compression failure. Getting gas, getting spark...just not firing. It did backfire once out the carb.. Possible a head gasket failure between cylinders. Engine never bogged at all under 16" HG load. The machine has burned through coolant a little more than I am comfortable with in the last month and we did burn up a fan belt when the air pump bearing ceased causing the engine heat sensor to shut the machine down, so the loss may have been pressuring out from a leaking head gasket. Worse case scenario, I replace the head. Currently in the process of pulling head (new gasket set on the way).

Wish me luck!

 

[The Magician]

Do a compression check. It will tell if cylinders are leaking.

 

[Amazing]

if it backfired you are getting spark.. sometimes, and some fuel.

 

[Kevin B]

Replaced head gasket. Running like a champ again. Gasket failed between #2 and #3 cylinders. No head warpage, and the cylinder walls looked great. Adjust valves, cleaned up the entire engine and running fantastic!

 

[Contemporary Carpet Clean]

Im glad to hear that your TM is back up and running. I am suprised to hear at 2500 hours that your head gasket failed. Did your mechanic sound suprised at that. Those are supposed to be some heavy duty industrial engines. But then again nothing suprises me today!!!

 

[John Olson]

We have a maxx 470 right here right now with 3200 hours with the exact same problem.

 

[Hoody]

Replaced head gasket. Running like a champ again. Gasket failed between #2 and #3 cylinders. No head warpage, and the cylinder walls looked great. Adjust valves, cleaned up the entire engine and running fantastic!

I still would have milled the head, just saying. Be sure to watch the bottom half of the engine now for any failures. Usually when you replace or repair the top half, the bottom will give you grief, but not always.

 

[joe harper]

Replaced head gasket. Running like a champ again. Gasket failed between #2 and #3 cylinders. No head warpage, and the cylinder walls looked great. Adjust valves, cleaned up the entire engine and running fantastic!

I still would have milled the head, just saying. Be sure to watch the bottom half of the engine now for any failures. Usually when you replace or repair the top half, the bottom will give you grief, but not always.

"Didn'T..know you were that sMaRt"... :shock:

You must have LeRnT sOmTin..from...BaWB.... 8)

 

[John Olson]

he pays attention when he is here at the shop.

 

[Kevin B]

Replaced head gasket. Running like a champ again. Gasket failed between #2 and #3 cylinders. No head warpage, and the cylinder walls looked great. Adjust valves, cleaned up the entire engine and running fantastic!

I still would have milled the head, just saying. Be sure to watch the bottom half of the engine now for any failures. Usually when you replace or repair the top half, the bottom will give you grief, but not always.

Repairing the top half as in replacing a head gasket? For the record...I've put 1900 more hours on this machine and still going strong.

 

[Hoody]

Good to hear, Kevin! And yes, by top half I meant anything to the with head. When you blow a head gasket you get a loss in compression, SOMETIMES if the engine runs long enough with that problem other components will change slightly to try and make up for the loss in compression. Once the problem is fixed and compression goes back to normal a bearing or something will go.

I've had it happen in small engine stuff and on vehicles, even something as weird as messing the timing up after its fixed.