7.4 MPI Mercruiser Engine - Engine cranks about 30 Seconds before it starts:-gctid827679

[Guest]

Hi Guys,

About 4 weeks ago I was out and the engine just died while running. We got towed in. When I went to work on it I found that the Cap and Rotor were Bad. The Cap was dirty and the Rotor had exploded into about 5 pieces. Then after I replaced them the engine started OK. I noticed that it took about 20 seconds of cranking before it started however. I did not think much of it at the time since I had an issue and I just repaired it and was happy that it was running, without costing me a fortune. But over the last 2-3 weeks it seems to be stretching out the cranking time a few seconds more. I actually ran the 2 batteries almost dead. The batteries are getting a bit old, but there seems to be something going on with this engine when trying to start it. I have owned the boat for 7 years and for the last 6-1/2 the boat has always started within 3 to 5 seconds of cranking the engine. I was thinking maybe the timing was changed somehow? I don't understand why the change in the cranking time of the engine when trying to start it after changing only the Cap & Rotor. Any Ideas guys?

Thanks a Bunch

Eddie

[flyman219]

I would look to see if the exploding rotor might have disturbed something inside the dist. Have you been keeping up on the servicing of the motor?

Mike

[Nauti_Mike]

Are you certain it's not the old battery's just too weak to crank her over.

[canoel]

Let's forget that you had a cap and rotor issue for a minute.

First check the batteries.

It is either lack of fuel, or lack of spark.

When cranking check for spark.

Check fuel pressure, fuel pump should do an initial 2-3 second prime.

Now don't quote me here, but in many of the GM based MPI systems if the cam sensor(in many cases the cam sensor is in the distributor) goes bad, the computer will crank for 20-30 seconds, then take it's signal from the crank sensor.

If you have good spark and fuel pressure, get a scan tool and see if you are getting a cam signal when cranking.