1997 175XR2 Mercury Outboard Stalling At Idle

[Plan-B]

I have a 1997 Sea Rayder with a Mercury 175XR2 motor and jet drive assembly. It stalls at idle after the motor warms up. If I rev the motor up to a steady 1200 rpm or more it will run fine. Since the problem (about a month ago now)accured I have rebuilt the carbs, changed the spark plugs, checked the compression (all cylinders are same at 120psi), checked all fuel lines, replaced the fuel filter, bypassed the fuel tank with small tank of fresh gas, taken out the fuel tank pick-up tube and inspected. The bout starts fine even in the water after warm up it will stall at idle. just above idle it runs great. It excellerates very well with the top rpm approx 5200 and runs about 50 mph steady with no problems. Running throttle up and down to manuver is perfect. Just idle. About a month before problem if the boat idled for about 5 minutes the temp alarm would go off. If I put in gear and started moving the alarm would shut off and all would be ok. This stopped happening as quick as it started so I thought it was sand in the water pump assembly and cleared itsself. Thank you for any feedback you may offer.

[j_martin]

1997 XR2 175 doesn't match in any way.

What you're looking for is an air leak into the fuel supply line before the fuel pump, or a problem with the fuel pump itself. Definitive test would be a temporary fuel pressure gauge which will probably go to zero as it stalls.

hope it helps
john

[Faztbullet]

1997 XR2 175 doesn't match in any way.

Its a Sportjet.2.5L motor
http://www.mercruiserparts.com/selec...28POWERHEAD%29

[CharlieB]

'Jet' motors are always under load, the jet pump is constantly moving water. Shifting merely redirects the diverter to change direction of the water stream. So it may be that Neutral or Reverse actually increases motor load as with the diverter restricting pump outlet raises pump pressure, raising the motor demand for idle fuel mixture.

Raising throttle and RPM to 1200 the motor is beginning to draw fuel thru the main jet, fattening the mixture.

This leads me to ask how long since these carbs have been properly cleaned, as I seriously suspect the idle circuits are beginning to show symptoms of dirty carbs.

5200 is just a hair low for WOT RPM. This motor may have the pump rotor shimmed just a hair too tight, readjust the shims to add a couple thou more rotor to case clearance will increase WOT RPM, 5600 with a normal boat load should increase performance and motor longevity.

[canoemang]

5200 is just a hair low for WOT RPM. This motor may have the pump rotor shimmed just a hair too tight, readjust the shims to add a couple thou more rotor to case clearance will increase WOT RPM, 5600 with a normal boat load should increase performance and motor longevity.

By shimming it away from your liner you may gain rpm's but all your doing is causing it to cavitate.. you wont gain anything performance wise. You would be chasing the wrong end of this problem by doing this.

I turn a 4 blade impeller 5400 rpm with a in-line 6 115, shimmed tight (to spec), when the liner starts to wear ill get up to 5600 with slippage/cavitation and have to shim it back within spec.

[Plan-B]

The new fuel filter that I installed is glass. I seen a few air bubbles in it on occasion. The gas tank is also very low. I will put some gas in and try to see if I can find a air leak in the system.

[Plan-B]

I just pulled the carbs off, cleaned and completely re-built them as I have on my other boat (200 yamaha) I turned the mix screws in just snug and backed them out 1 1/2 turns each as specified in my shop manuel. If I lean a little (ccw) I will try a 1/8 turn (ccw) each to test. Thank you.