Prochem APEX running too rich, choking after 2-3 hours under full load and throttle

[roto-kleen]

Dear TM Mechanic or other smart person,

I will make it worth your while if you find the issue with my machine. I'm at my wits end, my sanity is hanging in the balance...I'm willing to travel

Here's what it's doing:

Runs perfectly without load at full rpm both vac and water pump engaged, sealing vac inlets or doing extraction runs perfect for 2-3 hours lots of suction, runs smoothly. Then it starts to choke...powers down and struggles to stay running even blows some black smoke from exhaust...chugs, just runs rough and vibrates pretty violently. I take the load off by pulling my vac line of the vac inlet and it powers up again...no problem but as soon as I attach the vac hose to the vac inlet again (still at full throttle) it chokes and struggles to stay running. I lessen the throttle to 3/4 and it remedies it (that's how I get through a job when it acts up) with less suction though. Not a nice feeling when you think it might quit completely during a job, then comes the insurance claim! AWESOME.

I've replaced the entire fuel system and ignition system even the coils, plugs, wires and caps...here's everything else I've done to attempt to remedy/correct my issue with NO result:

checked, tightened and aligned blower belt - good
changed fuel pump, both filters and new lines too
checked air filter - good
carb cleaner spray
ran fuel directly out of fresh can
installed new battery
took to kubota dealer, said choke cable unseated/loose, coming on intermittently, said fixed, charged me $300 for not fixing it!
checked all wiring - seems good
all pump oil levels good
engine oil and filter changed every 100 hours
I run non-ethanol fuel through it
I use soft water only

I'm going to lose my mind if this machine doesn't get fixed and soon...my business is suffering and it's embarrassing. I'm running out of excuses to tell my customers...HELP!

 

[Shane T]

While its running bad and blowing black smoke, can you look at the choke butterfly and see what position it is in? Is there a return fuel line on that unit?

 

[roto-kleen]

Choke is fully closed (looking at it from engine compartment, not console)
has a return fuel line yes.

plugs carbon up/foul when runs rough

 

[Shane T]

Have you done a compression test?

 

[dgardner]

Sounds like a fuel delivery issue, resulting in a lean mixture. Reducing throttle reduces the fuel needed and it can keep up. Next time it happens shoot just a little carb cleaner into the air cleaner inlet while it's happening. If the motor smooths out that's what's happening. If your pump, etc is really OK, then likely issue is in the carb - plugged needle/seat or stuck float (unless you have fuel injection, whole 'nother deal).

 

[Shane T]

Dan, Why do you suggest a lean mixture when it is blowing black smoke and fowling the plugs.

 

[dgardner]

Good question! The key is reducing throttle (less air) makes it run better, suggesting too little fuel.
If the motor is too lean, the fuel can't ignite, resulting in unburned fuel. That can mimic a rich mixture and has fooled me before. Make sense?
If my suggested test makes it run worse, then I'm wrong and it's too rich.

 

[roto-kleen]

Too rich if fowling not lean...I've sprayed carb cleaner into air intake and it stalls out engine pretty much...doesn't run smoother no. I'm hoping its just the carb, I guess the only way to know is take it apart and clean/rebuild it?

How do I do a compression test Shane?

 

[dgardner]

Ryan, you said above that when problem happens the choke is fully closed. You meant open, right?

 

[roto-kleen]

choke is off...so open ya sorry

 

[Shane T]

Ryan, you said above that when problem happens the choke is fully closed. You meant open, right?

Yea, Ryan please clarify. While running bad is the butterfly closed(choking the air off) or is it open(allowing max air through)?

 

[dgardner]

So, still leaning toward carb needle/seat/float, except sticking open rather than closed. Have you tried rapping the float bowl with a wrench when it happens? Might unstick the works temporarily, pointing to the problem.

The only other thing I can think of is something in the return line (inside the tank, most likely, since you replaced the external lines) blocking off the return flow. This would cause your fuel pressure to jump up too high, overcoming the float and forcing fuel into the intake. Only way to really check this is to plumb in a fuel pressure gauge at the carb.

 

[roto-kleen]

choke is not engaged when running rough in other words open, allowing max air

 

[dgardner]

Didja ever figure it out?

 

[Willy P]

Not the last time I talked to him. He took it to a Kubota dealership and no joy there. No luck over the phone withProchem.He was gonna take it the Prochem dealer nearby and see what they can do. Shitty luck, Ryan's a good guy.

 

[GeneMiller]

Was this ever solved

gene

 

[Lars]

Our prochem machines are doing the same thing...
i think it's a cooling issue. These machines run very hot. I put a airmover on high speed pointed at the machine and everything runs smoother and cooler.

 

[Mike Draper]

I'm willing to bet when it's all said and finished it has more to do with a modification prochem made rather than an issue because of the Kubota engine only.

 

[Bryan S. Bennett]

I had an issue years ago with my peak. Check the fuel line closely where it connects to the fuel tank. The fuel line had a slight crack in it under the hose clamp. As the outside air temp would change the hose would expand and eventually lose its prime shorting the engine of fuel.

 

[Vivers]

Prochem APEX running too rich, choking after 2-3 hours under full load and th...

When this happens can you pull the choke out slightly and does that remedy the problem?
Otherwise it does sound like a carb problem. I have an Apex as well

 

[Dan]

Sounds characteristic of fuel pick up sucking air.

 

[GeneMiller]

I had an issue years ago with my peak. Check the fuel line closely where it connects to the fuel tank. The fuel line had a slight crack in it under the hose clamp. As the outside air temp would change the hose would expand and eventually lose its prime shorting the engine of fuel.

He said he replaced both lines, unlikely he has a crack unless he over tightened the clamp.

Gene

 

[Vivers]

Rebuild carb and see what happens

 

[Mike Draper]

well, its been months since the original post. Is it fixed? tell us what it was?

 

[steve_64]

my first thought was its getting too hot in the van or lack of oxygen from exhaust filling the van up.

i just read this for the first time.

 

[GeneMiller]

Well did this ever get solved. Guessing no fun without a solution.

Gene

 

[Vivers]

I also like to hear the outcome as I own a Prochem Apex also

 

[Able 1]

Me too!

 

[dgardner]

He hasn't logged in in about a month.