4.3 MPI Starting Problem

[jfrenzel]

2003 4.3 MPI 166 hours. Engine starts and runs great reaches full rpm and speed. Never problem before. Last two days won't start for a couple of hours after running. If it does start rough idle and won't speed up. Leave alone an engine will start and run great. No ethanol in the gas. Water temp of the lake 90% engine runs at 175 or below. Two new fuel filters, spark arrestor is clean and changed plugs loosen gas cap. Last went to local dealer tried sea foam and fresh gas. Last today I had the battery tested as it was orignal and dealer said it could be a problem because where I purchased our boat a 500 CCA battery was installed and all along it should have been a 750 CCA said this might not power the electronics of our boat. Voltage with the old battery was 12.4 ona digatal meter. Looking for ideas or thoughts. Thanks Jon

 

[Don S]

Re: 4.3 MPI Starting Problem

If the water temp is 90?, I hate to think what the air temp must be.
I would bet your engine compartment is way overtemp when you shut the engine off and it heat soaks causing a vapor lock on the electric fuel pump.
Might take it for a run and when you shut it off next time, just open the engine compartment and give it a try after a while to see what it does. If it works, then it's just too hot in your engine compartment.

Here is a 99 service bulletin Merc had out on Vapor lock and what to do about it.

http://www.boatfix.com/merc/Bullet/99/99_07.pdf

 

[jfrenzel]

Re: 4.3 MPI Starting Problem

Thanks for your help, changed the battery and no more problems so far. I think should try this for awhile unless you think we are masking a problem.
Thanks Jon