3.0 Mercruiser Cold Start Problem

[bign1514]

My first post because I'm stuck, but been getting information for this forum for years.

1996 SeaRay 175 with a Mercruiser 3.0

Three years ago put a new carb with (5 hours on it). Needed to be replace because boat sat for 4 years unused. After replacement boat started and ran perfect.

This year I changed the oil and filter and ran some seafoam at the beginning of the year - boat ran perfect and started in 2-3 tries.

About a month ago the boat won't start anymore with out starting fluid. Once started she runs great and will start. Only if it sits unused for more then 3 days, then I have a problem with the cold start.

- Anti-Siphon value seems goods
- Fuel filter holding fuel (full)
- I'm getting some squirts of gas with movement of the throttle.

I've been reading things about the oil pressure senor (fuel pump won't work if it doesn't detect pressure) but did notice last weekend at idle the boat was showing around 30 psi of oil pressure at idle. Then at WOT around 50-60psi.

Should pressure be at 40psi at idle? (I know most autos are)

I don't really want to bypass the oil pressure sensor to the fuel pump!

Does the fuel pump - pump fuel when the engine is running (carb working by siphon)??? Hence, maybe a faulty fuel pump at start?

Anyone have any ideas to solve this cold start issue?

Anything would be greatly appreciated!

 

[Don S]

Re: 3.0 Mercruiser Cold Start Problem

Do you pump the throttle a time or two when starting cold?
If you do, and it doesn't start, then I would be looking at the accelerator pump. It may not be pumping as it should.

I've been reading things about the oil pressure senor (fuel pump won't work if it doesn't detect pressure) but did notice last weekend at idle the boat was showing around 30 psi of oil pressure at idle.

You don't have any of that, that is for electric fuel pumps, and the 3.0L engine all have mechanical pumps.
Even if it did have electric, those pressure switches energize at around 5 psi.