300X Help??

[graygoose]

Just had an issue with my starboard motor and thought someone on here may be able to help me diagnose the issue.
Was running fine with both engines around 5800 rpm. starboard started losing rpm slowly, so I shut it down.
When I try to restart it turns over fine, ( no knocking ect.. )
Will not start without me applying a lot of throttle (as if flooded.)
Will only stay running at around 2K rpm for a while, then dies.
Lots of raw fuel and oil coming out of the lower exhaust port.

I removed all the plugs and there are no obvious fowled plugs.
Motor turns over freely with what feels like good pressure from each plug hole.

 

[n2otoofast4u]

When was last time injectors were flowed/cleaned?

 

[graygoose]

When was last time injectors were flowed/cleaned?

It has been a while since that was done. more than 8 years ago.
Sent all of them from both motors to Brucato in NC to be cleaned and calibrated.

Injectors / fuel rail was my first thought also on the problem.
Had to leave Havasu early Sunday and didn't get a chance to diagnose the problem more.
Frank on Scream & fly suggested TPS sensor.
But doesn't that just tell the ECU off and on at idle?

 

[graygoose]

I forgot to put in the 1st post.
Was some raw fuel also in the bottom of the air plenum.

 

[n2otoofast4u]

I forgot to put in the 1st post.
Was some raw fuel also in the bottom of the air plenum.

I was just checking with @JUSTWANNARACE and then read this. I would lean towards reeds after reading this.

 

[graygoose]

I was just checking with @JUSTWANNARACE and then read this. I would lean towards reeds after reading this.

Yep, I'm thinking the same now after talking to a few others. how hard are they to change out? any special tools needed?

 

[HST4ME]

Check the pulse pump for a diaphragm tear, and fuel pressure regulator reference hose for fuel. There is always fuel puddled in the bottom of the plenum on those motors.

 

[NeedlesRat]

Just did the reeds on both my 300X’s and did the injectors at the same time. It was a pretty easy job. 12 bolts to remove the plenum and intake assembly, then 2 bolts per reed cage to remove the reed cages from the intake assembly. The kicker is that the price is astronomical to get OEM cages because they are sold as a set with cages and reeds, and like me, you’ll need 12. What happens is the neoprene on the cages wears along with the reeds so even with new reeds, you may need cages since the seal won’t be great when the corners of the neoprene on the cages are broken off. I ended up sending my cages to Chris Carson marine in FL and he machined the cages and removed the neoprene and he makes reeds that are slightly larger to compensate for the removed neoprene. I bought a service manual directly from Mercury and it was a big help. Feel free to PM me and I can give you my number and walk you through the job and if your at all close to where I’m at (Santa Clarita), I can help you. Just put everything back on two weeks ago and ran the boat during SCFW and it ran flawlessly.

 

[graygoose]

Just did the reeds on both my 300X’s and did the injectors at the same time. It was a pretty easy job. 12 bolts to remove the plenum and intake assembly, then 2 bolts per reed cage to remove the reed cages from the intake assembly. The kicker is that the price is astronomical to get OEM cages because they are sold as a set with cages and reeds, and like me, you’ll need 12. What happens is the neoprene on the cages wears along with the reeds so even with new reeds, you may need cages since the seal won’t be great when the corners of the neoprene on the cages are broken off. I ended up sending my cages to Chris Carson marine in FL and he machined the cages and removed the neoprene and he makes reeds that are slightly larger to compensate for the removed neoprene. I bought a service manual directly from Mercury and it was a big help. Feel free to PM me and I can give you my number and walk you through the job and if your at all close to where I’m at (Santa Clarita), I can help you. Just put everything back on two weeks ago and ran the boat during SCFW and it ran flawlessly.

Wow, Great info. I live in Valencia. But unfortunately, the boat lives in storage in Havasu. no room for it here. I will be going back out there in the next week or so to do more diagnostics. if it turns out to be reeds, I may tow it back here to do the work. how long was the turnaround time for the cages at Chris Carson marine? I know Brucato has about 1 1/2 to 2 weeks turn around on injectors.

 

[graygoose]

What motors?

300X

 

[graygoose]

Check the pulse pump for a diaphragm tear, and fuel pressure regulator reference hose for fuel. There is always fuel puddled in the bottom of the plenum on those motors.

When you say pulse pump, which of the following two images highlighted in yellow are you talking about?

 

[HST4ME]

The square one.

 

[NeedlesRat]

Turnaround time was quick. Maybe 1 week. I think what was the longest is the shipping time from SCV to Florida and back. My boat is stored in Needles so I had the same problem as you. What I did was take the intake assemblies off and brought them home as one piece and then took it apart here in the garage. Which in turn had the injectors here as well since they come with the intakes. I took my injectors to Teague and had them clean/flow them. Carson also sells the gaskets for both the plenum and the intake assembly.

Wow, Great info. I live in Valencia. But unfortunately, the boat lives in storage in Havasu. no room for it here. I will be going back out there in the next week or so to do more diagnostics. if it turns out to be reeds, I may tow it back here to do the work. how long was the turnaround time for the cages at Chris Carson marine? I know Brucato has about 1 1/2 to 2 weeks turn around on injectors.

 

[graygoose]

Thanks everyone for the great advice.
Going to drive out to Havasu to do the diagnostics in a week or so.
Hoping that it is just the pump or regulator issue HST4ME suggested. If it is the reeds and injectors as NeedlesRat thinks.
I will probably take off the intakes on both motors bring them home and have injectors and reeds done at the same time.
I will post again with the results.

 

[NeedlesRat]

Thanks everyone for the great advice.
Going to drive out to Havasu to do the diagnostics in a week or so.
Hoping that it is just the pump or regulator issue HST4ME suggested. If it is the reeds and injectors as NeedlesRat thinks.
I will probably take off the intakes on both motors bring them home and have injectors and reeds done at the same time.
I will post again with the results.

let me know if you need any help if it is reeds

 

[graygoose]

Quick update.
I was able to get up to Havasu last week and do some diagnostics.
started with the throttle position sensor being the easiest and cheapest part to test.
Unfortunately that did not solve the issue.
Then went on to swapping out the whole fuel rail assembly from port to starboard engine.
She fired right up and idled fine. did it a few times just to be sure.
Brought both the fuel rails back with me to have all the injectors tested, cleaned, and calibrated.
Dropped it off at Teague Friday.
Mike called today and said all injector were working ok just needed cleaned and calibrated.
He then tested the fuel rail pressure regulators on a vacuum.
One was working properly, and the other was shot. probably a torn diagram.
Decided to replace the regulators on both motors to be safe.
Pricy little suckers though. $340 each. (highlighted in yellow on image )
Thanks to all for helping me out with this.
And a big thanks to Mike at Teague for figuring out a way to vacuum test the regulators and find the issue.

 

[HST4ME]

Quick update.
I was able to get up to Havasu last week and do some diagnostics.
started with the throttle position sensor being the easiest and cheapest part to test.
Unfortunately that did not solve the issue.
Then went on to swapping out the whole fuel rail assembly from port to starboard engine.
She fired right up and idled fine. did it a few times just to be sure.
Brought both the fuel rails back with me to have all the injectors tested, cleaned, and calibrated.
Dropped it off at Teague Friday.
Mike called today and said all injector were working ok just needed cleaned and calibrated.
He then tested the fuel rail pressure regulators on a vacuum.
One was working properly, and the other was shot. probably a torn diagram.
Decided to replace the regulators on both motors to be safe.
Pricy little suckers though. $340 each. (highlighted in yellow on image )
Thanks to all for helping me out with this.
And a big thanks to Mike at Teague for figuring out a way to vacuum test the regulators and find the issue.

same regulator as used on a honda and several other cars. I probably should make a post of all the parts I have cross reference so people stop getting fucked by mercury.

All of the merc outboard fuel systems (and I/O) that use a vst are trash, you're far better off converting over to a true bypass system.

 

[graygoose]

same regulator as used on a honda and several other cars. I probably should make a post of all the parts I have cross reference so people stop getting fucked by mercury.

All of the merc outboard fuel systems (and I/O) that use a vst are trash, you're far better off converting over to a true bypass system.

HST4ME, can you post the honda part number? I just paid $341 each for these. May still be able to cancel the order. Thanks for the info.

 

[HST4ME]

Kiehin NR-1

Fuel Pressure Regulator Assembly Mercury Mercruiser Quicksilver Part 805227A1 | eBay

1 X Fuel Pressure Regulator Assembly.

www.ebay.com

Same deal, add the appropriate size barb and there you go

 

[Rayson1971]

Quick update.
I was able to get up to Havasu last week and do some diagnostics.
started with the throttle position sensor being the easiest and cheapest part to test.
Unfortunately that did not solve the issue.
Then went on to swapping out the whole fuel rail assembly from port to starboard engine.
She fired right up and idled fine. did it a few times just to be sure.
Brought both the fuel rails back with me to have all the injectors tested, cleaned, and calibrated.
Dropped it off at Teague Friday.
Mike called today and said all injector were working ok just needed cleaned and calibrated.
He then tested the fuel rail pressure regulators on a vacuum.
One was working properly, and the other was shot. probably a torn diagram.
Decided to replace the regulators on both motors to be safe.
Pricy little suckers though. $340 each. (highlighted in yellow on image )
Thanks to all for helping me out with this.
And a big thanks to Mike at Teague for figuring out a way to vacuum test the regulators and find the issue.

So Tcm can clean and test outboard fuel injectors ?

 

[graygoose]

So Tcm can clean and test outboard fuel injectors ?

Yes, they did mine.

 

[28skater]

same regulator as used on a honda and several other cars. I probably should make a post of all the parts I have cross reference so people stop getting fucked by mercury.

All of the merc outboard fuel systems (and I/O) that use a vst are trash, you're far better off converting over to a true bypass system.

Mercury 300x Fuel pressure regulator # 840411T. What is the cross reference number? Thank you