350 Mag - Wont start after impeller freeze

Low hours engine, hadn't been run in a while.

Engine started on first key turn, ran and idle about 4 mins. in the driveway with hose connected to water intake. Ran fine, water comming out exhaust, etc. . Went to turn the water up a bit so I could ran at higher RPM.

Engine stopped, tried to restart, noticed impeller wheel was frozen and belt slipping over it as I tried to restart. Wheel could be turned by hand but it was shot (one rubber fin ripped). I replaced impeller but now engine wont turn over - Tested fuel pressure at the rail and getting some but doesnt seem real high. Dist cap contracts were dirty so cleaned. I get slightly more attempt to start with started fuild but not much more. Doesnt seem to be trying any harder to start with coil wire disconnected than with it connected.

So --- is freezing an engine at low idle by freezing the water impeller likely to bend something or cause the timing chain to slip a notch? What it the dist rotor direction suppose to be with engine at TDC on the timming mark (I dont see a notch on dist housing).? Thanks ? Other things to look at?

It's cranking ? You got spark at the plugs? Reply we can go from there.

Its cranking not firing. I think I have spark (it tries to fire a little with starter fluid), but I think it might be weak. Tested fuel PSI at the injectors, after the fuel pump cycles when turning the key, its at 30 psi.

ooo you should have 2 fuel pumps, this one i have to leave to maybe Ghost, or Guy, Hy or the other younger guy's knows this new style stuff better then me.

Went a got a plug tester.

No spark anywhere...or at least not enough to light the light.

I needed a new dist cover/rotor anyway, so I am going to pick that up in the am and start debugging from there if that doesnt fix it. It looks like the impeller was just coincidense...maybe just stopped an already weak motor.

gbow1 said:

Went a got a plug tester.

No spark anywhere...or at least not enough to light the light.

I needed a new dist cover/rotor anyway, so I am going to pick that up in the am and start debugging from there if that doesnt fix it. It looks like the impeller was just coincidense...maybe just stopped an already weak motor.

Click to expand...

You may have accidentally unplugged a wire somewhere while trying to change out your impeller? Maybe you turned off the lanyard kill switch at the helm area of the boat?

Does the coil wire have good spark?

Is this EFI or carbed? What year?

" Injector " " pump 30 psi " Got to be efi. I know how it works i don't know how to give detail trouble shoot advice. These guy's know even what color wire.

Someone will come along. Thats why i am bumping this back up.

I pulled the manual for it -

The boat is 1998 350 MAG MPI SKI.

30 PSI fuel at the rails is the expected reading.

Lanyard is fine.

Cranks but no spark on the plugs. (Dist cap/rotor replaced). I noticed that with key "on" but not cranking that I have 12 VDC on the wire from the coil to the Dist Cap........but with the starter engaged and engine cranking the Voltage on the coil wire drops to 8 VDC ish. So I think its probably just a weak battery....I have it on a charger now.

Probem solved -

Step 5 on Thunderbolt V troubleshooting flowchart. No signal from the ing sensor inside the distributor, to the ECM computer, so the ECM never tells the coil to spark. (Step 5 has you bypass the sensor and tap the green/white lower dist wire to ground and see if it sparks a grounded coil output (via spark tester)...it did, so bad sensor. Cleaned grounds for sensor (old sensor grounds through attachement screws or dist housing dist retainer clamp....bad design), tested and meter said they were grounded. Still no joy, so bad sensor. Replaced sensor Quicksilver part # 87-892150Q02, or Mallory 9-29804......problem solved, starts and runs great.

Good, now when some posts with the same problem you jump in and give the fix.

New style chit gotta love it when it runs good. When it don't it's enough to give ya angina.