Fuel Return Line on Cat 3512 Genset

<...And it is accidently turn off . What are the consequences?...>

Too much fuel will enter the engine. It will either:

• accelerate without limit, or
• emit a lot of smoke from the exhaust, or
• both of these.

In any case it won't do it any good. Catastrophic self-disassembly might ensue.

The best plan would be to remove the valve so that it cannot be accidentally turned off.

3512 engines rather mechanical or electronic 3512B series have whats known as unit injectors. So you would be closing the circut that recirculates to your fuel tank and keeps the injectors cool and functioning properly.

You WOULD NOT overfuel or the engine WOULD NOT run away, but serious power loss will occur due to the injectors becoming overheated as will over presureization and possible damage of the fuel circut. Damage to your injectors is probable depending on the extent of the closed return condition.

For service reasons a valve is needed, however it needs to have restricted access. A check valve is nornmaly installed into the system thus the only time the typical valve needs to be closed is to service the check valve or piping.

I hope this answers your questions.

Truckers take a dime and drill a 1/8in hole in it and place it as a gasket where the return line goes into the fuel tank to build up more pressure on the injectors.

Cutting it off competely will force al the pressure from the injector pump over the whole fuel system on the engine. This will lead to excess fuel use and unneeded wear on parts an early failure of the injector pump. In my opinion.

Restricting the return to gain performance on an engine with UNIT INJECETORS is an absolute false statement. Remember, we are talking about a 3500 series Caterpillar NOT a 3400 series that you typicaly see in a truck.

A unit injector is in fact a high pressure pump that is self contained. The actual fuel pump is there for two reasons; 1- to feed the injectors with a steady supply of fuel at low pressure. 2- to constantly circulate fuel from the tank in order to keep the injectors cool. IF YOU RESTRICT THE RETURN YOU WILL NOT COOL YOUR INJECTORS PROPERLY PERIOD, END OF STORY!

I strongly recomend either beliving this or contacting your local authorized Caterpillar dealer in your area and getting the correct information from them.

There are also operation and maintenance courses avalible from Caterpillar.

I did not intend to offend the truck driver, but a person should not give false information. If you dont know, dont share your ignorance with someone who is looking for a real answer.

I was only telling him what real workd truck drivers do. If you had botered to read the rest of my post you would have seen I siad restricting the fuel flow in the tank return line would cause unneccessary damage to the engine.

Of couse you won;t so why bother "L".

The only reason to block or partially block the return line on a truck is because the primary fuel pump is not supplying enough fuel to the injection pump. It has been done often. Many older truck diesels use mechanical supply pumps which have a limited life. I replaced mine with an electrical pump.

Hint: electric supply pumps must be mounted below the tank level.