150 Optimax Fuel Pumps?

[SaltyDog]

2001 150 Opti OT274461

Motor is starving for fuel. Does it have three fuel pumps?

Im getting just a bit out of the schrader valve. What should the pressure be?

[SaltyDog]

The boat sat for two years so I changed the filter and cleaned out the VST tank. The port engine fired right up but starboard side get almost no fuel pressure

[SaltyDog]

The boat sat for two years so I changed the filter and cleaned out the VST tank. The port engine fired right up but starboard side get almost no fuel pressure 

[EuropeanAM]

3 fuel pumps. A Diaphram (Pulse) Fuel Pump, a Low-Pressure (external) fuel pump, and a High Pressure (internal to the VST) fuel pump.

Must have air pressure to get correct fuel pressure. Must have fuel present at the High Pressure pump or you get little (or no) fuel pressure.

What are the Air/Fuel Pressures when you attempt to start the engine? After 10 seconds of cranking?

[SaltyDog]

Thanks, I’ll check the pressures tomorrow.

How do I test the diaphram pump? The VST has fuel so it’s probably good.

How do I test the low pressure electric pump?

I’m thinking I could have screwed something up putting the VST tank back together. Anything particular that I should have replaced when I reassembled it?

[EuropeanAM]

Needle, O-ring, High Pressure Pump seal to Top Cover (at a minimum).

Pulse pump can be tested with a vacuum gauge and visual tests- just about as simple to go ahead and rebuild it, though.

Start with the air and fuel pressure tests- as they are the simplest, and if you monitor them when the engine is not running correctly, you'll know if it's fuel delivery related.

[SaltyDog]

Thanks Don. What kind of gauge should I bike to test these pressures, how high are they?

Can I test the low pressure electric fuel pumps by putting 12 V to it? Did they run constantly when the key is on?

[SaltyDog]

OK
The air and fuel pressure is the same on both motors 80 on the air zero when I turn the key on and then they crank up to about 75. It’s a cheap Harbor freight gauge though but the engine seem to be the same. The port engine runs good but the starboard cranks slower and I’m wondering if that’s the issue.

I’m cleaning up electrical connections now and I’ll see if it helps

[EuropeanAM]

Must check air AND fuel pressures at the same time, with liquid or glycerin filled/dampened gauges.

[SaltyDog]

What are we trying to test with these glycerin filter gauges? It would probably be easier for me just to replace whatever it is that’s being tested instead of trying to find gauges like that

[leonreno]

Those gauges are found at many auto parts stores, checking fuel pumps, etc.. not cheap parts.

[EuropeanAM]

What are we trying to test with these glycerin filter gauges? It would probably be easier for me just to replace whatever it is that’s being tested instead of trying to find gauges like that

Every component of the fuel and air system- you definitely don't want to just replace all of those.

[SaltyDog]

I’m beginning to think I might have a battery issue and not fuel issue. How much voltage is needed to start an Opti?

Also will a starter crank slower as it goes bad? Port engine spins much quicker than the starboard and the stbd starts right up.

[leonreno]

http://www.bbcboards.net/showthread.php?t=20671

Above is the battery requirement faq for Optimax motors

[SaltyDog]

Thanks. One more question how do I test the low pressure electric fuel pump?

[SaltyDog]

One more, what activates the injectors and is there a way to test them?

[SaltyDog]

I did a search and found a 9v battery will test the injectors. I don’t think they’re the issue though as the port engine runs perfectly.

Is it the ECM that controls them? Is there a harness that can go bad? Can I check voltage in the injector wires while I crank the engine?

Crank or throttle position sensors?

[SilverFox579]

You need to invest in a genuine Mercury service manual for your engine, worth every penny.

[SaltyDog]

OK I took off the number three injector and I’m getting less than one volt when cranking

[SaltyDog]

You need to invest in a genuine Mercury service manual for your engine, worth every penny.

I get that, but those things aren’t that easy to follow and a little guidance from people who do it every day would make things much easier. I might have to have a Merc dealer hook up a DDT to it and see if I have a bad sensor.