Prochem 405

SamIam · Apr 26, 2014

I have 2 the first has 3500 hours sat along time and had the carburetor cleaned out ran fine for 2500 hours, It not runs great but sometimes in the middle of a job it will almost stall and rev back up like the governor if doing some thing with gas.

I end up pulling the choke completely out and it runs fine at that point.

Once I restart the machine it doesn't do it again for a couple jobs sometimes.

It seams to start when under heavy load?

The second question is my older 405 never draws more then 3 gpm from chemical jug and sometimes doesn't draw at all,I tighten things up replace any brass but the chemical system has always been a pita.

wondering if the govenor might be going on the first machine and just mad at 2nd machine its a fresh water rinse only machine right now

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Lee Stockwell · Apr 26, 2014

Not the governor.

More likely fuel pump, especially if it's mounted too high or in a hot location.

dgardner · Apr 26, 2014

Lee, I was thinking fuel as well. Could it be as simple as a semi-clogged fuel filter?

Lee Stockwell · Apr 26, 2014

Yes, or more likely vapor lock.

Desk Jockey · Apr 26, 2014

If you ruled out everything else in the chemical pump system. Take a look at the check valve in the pump that the cylinder drives the chem pump. Could be debris, could be fractured.???

SamIam · Apr 27, 2014

Ya my guy didn't think it was governor but the the filter and pump aren't that old and when I pull the choke out it runs fine.

I know the fuel pumps are continuous flow so they start the flow then the machine draws through the pump afterwards.

I was thinking maybe the carburetor maybe having issues and pouring gas straight thru to the engine fixes it temporarily.

Normally pulling the choke would kill the machine when running fine.

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JS41035 · Apr 27, 2014

Does the flow gauge max out when you prime?

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Lee Stockwell · Apr 27, 2014

The Nissan carb doesn't "draw" fuel, the fuel pump must push it, 4 or 5 psi. If the carb is starving for fuel the choke acts like yours.

SamIam · Apr 27, 2014

Yes

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SamIam · Apr 27, 2014

Justin Stockwell said:
Does the flow gauge max out when you prime?

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SamIam said:
Yes

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Yes

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SamIam · Apr 27, 2014

Lee Stockwell said:
The Nissan carb doesn't "draw" fuel, the fuel pump must push it, 4 or 5 psi. If the carb is starving for fuel the choke acts like yours.

When you start these machines you hold the water pump switch to override by turning key and holding the switch you can hear the fuel pump running.

I was always under the impression it was running the whole time but it doesn't it feeds the machine till it starts then the machine draws the gas on its own.

Maybe John from superior can confirm that?

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SamIam · Apr 27, 2014

deleted

SamIam · Apr 27, 2014

SORRY a new kindle and it keeps reposting and not showing g anything oops.

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SamIam · Apr 27, 2014

Justin Stockwell said:
Does the flow gauge max out when you prime?

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Minor leak in three way valve stopped leak primes and runs at 3 flow max which is good enough.

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dgardner · Apr 27, 2014

SamIam said:
I was always under the impression it was running the whole time but it doesn't it feeds the machine till it starts then the machine draws the gas on its own.

Maybe John from superior can confirm that?

Well, I'm not John, but - it appears that the fuel pump does run continuously. Here is part of the 405 schematic. I will spare all the boring details, but I have highlighted two wires in red. One is to the fuel pump, one is to the ignition coil. They are connected together at the oil pressure switch. Thus, when the ignition coil has power (which it must for the engine to run), the fuel pump does too:

View attachment 4526

Unless there is a mechanical pump on the engine (in which case you wouldn't need the electric one), the electric pump has to run all the time.

SamIam · Apr 27, 2014

The switch is straight up and down to get power to the pump you have to physically hold the switch to a position during the starting up process once its released its straight up and down again showing the pump to be off unless the heat exchangers on.

Then the water pump is on you can turn off the heat exchanger the switch has three positions to of which can be set one has to be held. The held position is when the fuel pump is used to start the machine only.

The reason I know this is I replaced a fuel pump prematurely and after replacing it ended up being a bad float switch in the dump tank.

I called my tech guy and said It think the new pump is bad and he helped me trouble shoot it to the switch, sure enough when I bypassed the switch it ran fine.

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dgardner · Apr 27, 2014

Sam, once the engine is running, the oil pressure switch closes, in effect "holding" the switch on for you. Trust me on this, your fuel pump has power and runs any time the engine is running.

dgardner · Apr 27, 2014

It's easy enough to tell for sure. There is a connector in the wiring harness between the unit and the fuel pump.

Start the machine and get it up to operating speed. Pull the connector apart. This kills power to the fuel pump. If you're right you don't need it once the engine is started and it will continue to run fine for hours. If I'm right the machine will stop after a couple minutes (it will take a little time to use up the fuel in the carb float bowl).

Let us know how it goes!

JS41035 · Apr 27, 2014

SamIam said:
Minor leak in three way valve stopped leak primes and runs at 3 flow max which is good enough.

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Well If your chempump has been rebuilt with new diaphragm and disk. And your big chem check valve is clean. I would look at the metering valve. Take it out and clean it. Probably time to put some new clear hose on also. Just run new stuff on the outside of the frame and zippy tie it.

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Lee Stockwell · Apr 27, 2014

You can verify that the pump is running by watching the red glass light flicker.

SamIam · Apr 27, 2014

Lee Stockwell said:
You can verify that the pump is running by watching the red glass light flicker.

I thought that was for charging the battery that's the only red light on the front of the machine

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Lee Stockwell · Apr 28, 2014

SamIam said:
I thought that was for charging the battery that's the only red light on the front of the machine

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It is. However the pulses from the electric fuel pump are strong enough to make the red light FLICKER when the pump is running.

John Olson · Apr 28, 2014

Everyone already covered it but yes the fuel pump either works and the machine runs or it don't and neither does the machine. The carb does not draw fuel. The pump must maintain 4-5 psi as Lee stated.

SamIam · Apr 28, 2014

Makes since I made a bad assumption based off my guy statement he also said change fuel filter and add coolant instead of water which I've done oops ! I'll do that flush radiator and replace fuel filter and see if that helps! Thanks for putting up with me Lee

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Desk Jockey · Apr 28, 2014

Yea without enough coolant it runs until it gets hot then the high temp shuts her down until she cools off again. Only to continue that cycle.

SamIam · Apr 28, 2014

http://youtu.be/YNqGR7aGxE8

This is what it does it wS right after I started very thick carpet heavy load or sometimes if it shuts down cause it got to hot

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Desk Jockey · Apr 28, 2014

Wow that weird. It's as if something is trying to kill it.

It reminds me of when your tank is filling and the liquid level switch is shutting her off. ????

Shawn Abbey · Apr 28, 2014

I also agree that its probably fuel related. Even if you hear the pump running, it may not be pumping. You mentioned it sat for awhile. There may be some debris that could be breaking free and affecting your performance. I'd check both and confirm. When ethanol fuel sits for awhile, it develops condensation and water develops in the fuel. That may cause some of the metal components to rust.

Second, I would completely rebuild your chemical pump (diaphragm, check valves, everything!) and replace all low pressure lines from the jug, to the pump. Sometimes a pinhole may cause the variations. Also, theres a screen and a check valve in a manifold just behind the front panel on the left side. Pull those out, clean, inspect, and replace the check valve.

Also, how's your chemical flow indicator? Is it foggy? Could it be cracked anywhere? That may affect as well? It doesn't sound like it from your description, but you better check it anyway.

Sometimes, you have to replace the whole system to solve the problem. Its not very expensive, and will give you a good baseline and reduce your frustration!

SamIam · Apr 28, 2014

Doc Holliday said:
Wow that weird. It's as if something is trying to kill it.

It reminds me of when your tank is filling and the liquid level switch is shutting her off. ????

It did this when I first got it had 600 hours now had 4k.

My tech rebuilt the carburetor and it's been fine. The only thing is before it wouldn't run at all with out the choke out now it's sporadic. $9500 cash for used 405 with 660 hours isn't bad considering I paid about $300 for him to get it running right. I haven't had to do anything but change the oil and parts on the chemical system.

Shawn your right I just need to rebuild both systems from the ground up for the chemical flow issue. I know one minor leak and it's done.

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SamIam · Apr 28, 2014

In the video it sputters then runs fine when I pull the choke out out the choke back in it sputters.

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