I have a Volvo Penta 96 7.4L Gi EFI engine. At idle to 1500 RPM's the engine stumbles and then goes back to normal operation. Sometimes it will die, but I am able to restart with no problem. At cruise or wot I have no problem. Engine produces full power and runs smooth. Problem occurs after engine is warmed up.
I bought the boat last year and had to replace the fuel injectors, because the four rear ones were rusting badly and one had cracked and was leaking. I bought after market fuel injectors ( all 8) that were matched to the oem fuel injectors for half the price.
I have replaced the fuel filter. Checked fuel pressures, replaced the sparkplug wires, distrubor cap and rotor. Engine always starts right up and runs smooth. Again only between 800 (idle) and 1500 rpms does it stumble when it's warmed up in or out of gear. I also have a fuel flow gauge installed and when it stumbles the fuel pumps whine and fuel flow increases to about 25gph then right back down to normal.
I have flushed a blocked water line that comes from the fuel resvoir/vapor seperator. I really thought that was going to do it, but no luck. I also checked the float and valve.
My low pressure fuel side is reading 2 to 3 psi, book says 4 to 5 psi. But My guage is 0-120 psi. I was thinking it's just not accurate for that low of a reading. Could this cause my problem? The high pressure reads 40 psi, that seems correct. Any ideas would be most helpful. This is driving me crazy.
Jim
I bought the boat last year and had to replace the fuel injectors, because the four rear ones were rusting badly and one had cracked and was leaking. I bought after market fuel injectors ( all 8) that were matched to the oem fuel injectors for half the price.
I have replaced the fuel filter. Checked fuel pressures, replaced the sparkplug wires, distrubor cap and rotor. Engine always starts right up and runs smooth. Again only between 800 (idle) and 1500 rpms does it stumble when it's warmed up in or out of gear. I also have a fuel flow gauge installed and when it stumbles the fuel pumps whine and fuel flow increases to about 25gph then right back down to normal.
I have flushed a blocked water line that comes from the fuel resvoir/vapor seperator. I really thought that was going to do it, but no luck. I also checked the float and valve.
My low pressure fuel side is reading 2 to 3 psi, book says 4 to 5 psi. But My guage is 0-120 psi. I was thinking it's just not accurate for that low of a reading. Could this cause my problem? The high pressure reads 40 psi, that seems correct. Any ideas would be most helpful. This is driving me crazy.
Jim