White smoke on cold start

[S. Hockey]

I'm getting more white smoke on a cold start than I used to get, it clears up within a minute. I have also noticed that my electric fuel pump starts realy fast then slows to pulsing but does not shut off completly.I disconnected the fuel line at the filter located on the engine and no fuel came out. I inserted a gauge on the line and got about 5psi and still the pump did not shut off completly.I spoke to mechanics and some say that the cause is the injectors, others air in the fuel line(problem with electric fuel pump).The M 25XP engine runs fine.Questions.1. Is the electric fuel pump supposed to shut off completly once the system is pressurized or does it still pulse a bit?2. Where can one buy a replacement pump?3. Should there be fuel in the fuel line between the electric pump and the filter on the engine after the engine has been off for a few hours, or does the fuel flow back thru the pump?4. Could the injectors be leaking a bit?If others experienced this problem I would appreciate their response.Thankssa-hockey@telus.net

 

[Dave Slepoy]

pump filter

The fuel pump on my c-28 has a built in FILTER. the bottom of the pump assy will twist off and out comes a small filter cartridge. This is not a well know item and since it is after the primary filter most people forget about it. Dave

 

[Don]

White smoke

Questions.1. Is the electric fuel pump supposed to shut off completly once the system is pressurized or does it still pulse a bit?Mine always clicks slowly.2. Where can one buy a replacement pump?Marine supply or auto parts store for 1/3 the price.3. Should there be fuel in the fuel line between the electric pump and the filter on the engine after the engine has been off for a few hours, or does the fuel flow back thru the pump?There should be fuel in the line.4. Could the injectors be leaking a bit?I would think it would be possible, but the smoke should clear out within a few seconds. Keep a close eye out for a loss of oil or anit-freeze.

 

[Tim Dranttel]

The pump is fine

Nothing wrong with your pump. The M-25 engine has a continueous bleed system that bleeds small amounts of air from the system prior to getting to the injector pump. Because of this your motor is always by-passing a small amount of fuel back to the tank. That is why your pump clicks even with the motor off. From my experience there is always fuel in the line from the tank all the way to the motor. The pressure bleeds off over time but there should always be fuel. I have not replaced my pump but have heard that the automotive parts stores sell electric pumps that fit the bill for half the price.I would not think that the white smoke is a problem. White usually comes from water vapor. If the engine always smoked white it might be a sign of water jacket problems but since yours goes away after start up I don't think it is an issue. But I'm a pilot not a mechanic.Tim

 

[Bayard Gross]

White smoke is maybe oil from valve guides

The white smoke, as opposed to more of a white steam, is probably engine oil that leaked down into the cylinders from worn valve guides. As this just happens when you start the engine, it should not be a problem.I beleive some old Chyrsler 318 V-8's have this problem when starting, but otherwise they run fine. Maybe not intelligent to compare your engine to this, but at least shows such smoke need not cause immediate alarm.

 

[S. Hockey]

Thanks

Thanks to those that replied. A mechanic suggested that it might be the valve guide seals. Lots of possibilities. I also installed a Vernalift water lift muffler, I hope its not back pressure causing the problem. A friend of mine installed the same water lift with his m25 without any problems.