My starboard 2007 ETEC 250 recently started to lose power between 4000-4500rpm. RPM can be maintained if primer is pumped under this situation. No codes. Replaced Racor & W/F Separator. Checked all hoses & anti-siphon valve. Altermateed supply from Port to Starboard. Tested a auxilarly tank with fresh gas. No change in power loss. Electric Pump functions properly. Could this be a faulty Lift Pump? Thanks.
From your description, the motor runs if you use the primer bulb to feed fuel to the VST. That could indicate a faulty lift pump, loose pulse fittings in the block, or a restriction or air leak in the fuel delivery system.
The fuel system will have to be checked with a vacuum gauge and clear hose, the pressed in brass fitting inspected for looseness when the engine is warmed up, and the rail pressure must be monitored while running at all speeds. Your dealer is trained in these procedures. The motor should also be monitored with a laptop and the diagnostic software to check for any abnormalities while at the power loss rpm range.
Today I ran the Fuel System Pressure test and the results were normal at 19 PSI. Then I ran the Lift Pump Pressure Test and the results were normal at 5.5 PSI. I also ran the static & dyanamic tests via EV DIAG Software and everything seems to be fine. There aren't any active faults and engine runs fine under 4,000 RPM.
I did test for vacuum leaks and found them on both engines at idle by spraying carb cleaner at pulse hose block fittings, supply connections at W/F Separtor, at VST and Electric Fuel Circulation Pump. Engine RPM increased with the appliction of carb cleaner. All fuel lines and connetors are original and in goodshape with 650 hours/engine. Both engines have similar vacuum issues but only the starboard engine starves for fuel above 4000 RPM.
I have not performed the Lift Pump Vacuum Test, Lift Pump Diaphram Test or Fuel Injector Pressure Tests. What would your next course of action be? Thanks.
To clarify, I performed the Lift Pump Test and stabilized pressure is 5.5 PSI (normal is above 4 PSI). Conducted Fuel Pressure System Test found 35 PSI (normal is 20-35). The Fuel Pressure dropped with engine off to 19 PSI (normal is above 15 PSI). Is 35 PSI high indicating restricted filter, return fitting, damaged regulator or restricted return fuel rail to VST? I checked fuel return fitting to VST and fuel ran out when disconnected.
My gut tells me it is the Lift Pump and I would need to run the Lift Pump Vacuum Test & Diaphragm Test next. What about Fuel Injectors? I also ran the Static & Dynamic (@ Idle RPM) DiagnosticTests without any issues or existing faults. Do these Diagnostic Tests eliminate the Electric Fuel Pump & Injectors? Thanks!
a month ago
Yesterday I performed the Lift Pump Diaphragm Test. Both sides of the Lift Pump were tested at 15 PSI and they held the pressure and passed the test. I did not perform the Lift Pump Vacuum Test because I previously tested fuel from the port engine and from an auxilary tank and there was no change in the condition of the starboard engine. Did I make a correct assumption?
Previoulsy I performed the Fuel Pressure System Test found 35 PSI (normal is 20-35). Thinking 35 PSI was on the high side I checked the return manifold rail. I disconnected it at the return fitting to VST and energized the electric fule pump and fuel flowed out freely. I looked for a filter at the return fitting on VST and there wasn't one?!? My service manual shows one but the parts catalog does not list one?!? Using a strand of wire I inserted it into the fitting and did not notice any debris or clog although I could not insert it more than an inch or so. Perhaps that is the check valve of the Pressure Regulator. I pressure tested the regulator to 15 PSI+ and the check valve did not open. Is this my source of fuel restriciton at 4000+ RPM? What about the Fuel Injectors? Thanks.
a month ago - last edited a month ago
Did you perform the pressure tests at the time the motor was acting up?
When you sprayed carb cleaner on the motor, was the rpm increase from the fumes entering the air intake or from leaking fittings and hoses? Did the pulse fittings feel loose when the motor was losing rpm?
Yes, you should do the vacuum and air bubble test on the engine to find out how the plumbing is. Monitor the gauge and clear line at all speeds and especially when the motor is acting up.
The VST filter is listed in the 2012 parts books. Use a self-tapping screw to remove it.
a month ago
The Fuel Pressure Test and Lift Pump Pressure tests were done at idle. Are you suggesting I test both while engine is at 4000+ RPM? I assume this would be in gear and not in neutral.
The rpm increased from leaking fittings and hoses on both engines. I did not check the pulse fittings when the motor was losing rpm. I guess I would have to operate the engine with the cover off to do so. Again I assume this would be in gear and not in neutral.
I will run the Lift Pump Vacuum Test as suggested tonight while the engine is running and acting up.
What is the part# for the VST filter? I will also try to remove the existing one with a self tapping screw as well. Thanks!
a month ago
One last detail. In the event I don't prime the bulb while the engine is running rough, it ultimately stalls. It takes 15-20 minutes before the engine will restart. Primer bulb is pushing fuel through Lift Pump to W/F Separator to VST. Any thoughts?
a month ago
Do not let the engine die out. Air gets into the injection system plus the electric pump and the injector pumps do not get any lubrication when running dry. They often become damaged and/or start to wear causing debris to enter the fuel system. That is why it takes so long to get started, all the air has to be purged from the system.
You can look up parts and even order online at shop2.evinrude.com