1999 454 Mag MPI just quits - videos

Timing is set, sounds good, but the fuel is old. (3 years non-ethanol)
Will run with a pony tank and new separator tomorrow to confirm. I have a way to polish it, but I think the octane is probably kaput on that batch (80 gallons). ouch.
Gettin' there. Meanwhile, full cleanout of A/C raw lines, strainer and new hoses. Rewire of stereo, adding an amp for the cabin speakers instead of relying on the head unit built in amp.
 
douglee25 said:
What's the plan for this weekend?
Click to expand...
Wrapping some stuff up in Punta Gorda this morning at the RV, and then back up to replace the low pressure pump inline filters, and MAYBE a run this afternoon. Weather goes to shit tomorrow, and radiation starts Monday for 3 hard weeks. All I'm missing is time and money.......
 
370Dancer said:
Wrapping some stuff up in Punta Gorda this morning at the RV, and then back up to replace the low pressure pump inline filters, and MAYBE a run this afternoon. Weather goes to shit tomorrow, and radiation starts Monday for 3 hard weeks. All I'm missing is time and money.......
Click to expand...
Hang in there ......we are all pulling for you!
 
370Dancer said:
Wrapping some stuff up in Punta Gorda this morning at the RV, and then back up to replace the low pressure pump inline filters, and MAYBE a run this afternoon. Weather goes to shit tomorrow, and radiation starts Monday for 3 hard weeks. All I'm missing is time and money.......
Click to expand...
Prayers for you on all fronts!
 
Thanks guys. I was trying to save the fuel in the starboard tank, but proved to myself today that it's got to go. Ironically, the Port tank (same age) seems to be ok, but after all this, no sense in scrimping now. So, off to find a way to empty the tanks and get fueled. If anyone is aware of a dockside service that will pump out tanks around Sarasota/Bradenton, I'm all ears. Will contact Billy, who owns Mobile Boat Fuel to see if he does this.
 
So, I got to thinking......
How come my generator runs like a top off the STBD fuel tank, but the engine won't?
Started looking at what is inline that I bypassed with the remote tank, and that is an inline fuel filter (new, so that's not it), the shutoff solenoid (can see full gas in the transparent filter, so that's not it), and a low pressure secondary fuel pump to mitigate vapor lock in the summer in Florida. Bypassed the filter and pressure pump, and sonofabitch, it runs. Pressure pump doesn't look dirty, but it's an Amazon cheapo. I'll replace it. There's still a slight miss or something that causes the transmission to rattle a bit at dead idle out of gear on the STBD, but until I get it out and up on plane, I may be chasing something that I don't need to.

Here's a couple of vids and screenshots of the Fox Gateways. Once they started warming up, they settled into burning about the same fuel rate. Oil pressure on the "new" engine is 37 or so at idle, and the "old" engine is 54. I'll be watching to see if that smooths out after running it a bit. Now if the weather would cooperate........

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genny runs - why not the engine.mp4

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idling after low pressure pump removal stbd.mp4

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port status.PNG
stbd status.PNG
 
Cold oil should be in the 50's or higher. 37 psi for hot oil is OK. Assuming the same weight of oil in both engines. That oil is cold.
Swap the oil pressure sensors to see if the problem follows.
 
ok, gents, follow me here.
The "new" port engine has been slowly, and now more rapidly going from a smooth idle to a stall.
It will catch and stall immediately on restarts until I let it sit for a while. Then I can restart, but the cycle repeats after a minute or so.
I moved to 2 portable tanks with brand new gas, tapping in at the fuel water separator, bypassing the low pressure inline pumps I put on to overcome vapor lock. Hooked up a fuel pressure gauge, and when cold, It takes a few cycles of activating the HP pump prior to start to build up pressure past 30 lbs. As it begins to die, I see pressure falling off. Restarts cannot build pressure again until I let it sit.
So, sniffing and looking all over the fuel circuit for a fitting leak, or an o-ring injector leak. NONE. pumped it up a few times, and then pulled each plug checking for wet, which to me would indicate an injector stuck open. Nope. All light brown, slight smell of carbon, like they should be.

The injectors are new, so now I'm leaning back to the HP pump heating up and stalling. First thing in the morning, I can run for 15 minutes or more. right now, 1 minute on a warm engine. The pump is an after market, that I put on around 2018. Did I miss anything, or should I place the order? Fortunately, it's the port engine, so I can just about replace the pump in the bilge. What say you, wise ones? No, I'm not taking up golf.
 
370Dancer said:
ok, gents, follow me here.
The "new" port engine has been slowly, and now more rapidly going from a smooth idle to a stall.
It will catch and stall immediately on restarts until I let it sit for a while. Then I can restart, but the cycle repeats after a minute or so.
I moved to 2 portable tanks with brand new gas, tapping in at the fuel water separator, bypassing the low pressure inline pumps I put on to overcome vapor lock. Hooked up a fuel pressure gauge, and when cold, It takes a few cycles of activating the HP pump prior to start to build up pressure past 30 lbs. As it begins to die, I see pressure falling off. Restarts cannot build pressure again until I let it sit.
So, sniffing and looking all over the fuel circuit for a fitting leak, or an o-ring injector leak. NONE. pumped it up a few times, and then pulled each plug checking for wet, which to me would indicate an injector stuck open. Nope. All light brown, slight smell of carbon, like they should be.

The injectors are new, so now I'm leaning back to the HP pump heating up and stalling. First thing in the morning, I can run for 15 minutes or more. right now, 1 minute on a warm engine. The pump is an after market, that I put on around 2018. Did I miss anything, or should I place the order? Fortunately, it's the port engine, so I can just about replace the pump in the bilge. What say you, wise ones? No, I'm not taking up golf.
Click to expand...
Have you checked your return? You can also pinch the line and watch fuel pressure to see if it rises. You shouldn't need to cycle the key, it should be instant pressure. I'm thinking a bad pump or fuel return line clogged.
 
Well......you know the problem is fuel pressure. @douglee25 beat me to the punch on the return fuel line. Maybe I am missing something.......was the bypass at the water separator just for testing new gas? I would think the easier thing to do would have been to switch to the starboard tank for the port engine since the starboard engine is running fine.

My money is on the HP pump. You could swap it with the Starboard engine but I would not wish that on a friend. It is just easier to replace the Port pump.

As to the pump getting hot....that could be it.....but that comes back to the pump having a problem. You can always put a bag of ice on it if you want to test that theory.
 
Does that engine have the Cool Fuel module?
It seems to me that if the pressure is dropping and fuel pump is running then there is an issue with the Fuel Pressure Regulator. That is always on the return side of the injectors.
If the FPR the ONLY thing that hasn't been replaced.....
 
ttmott said:
Does that engine have the Cool Fuel module?
It seems to me that if the pressure is dropping and fuel pump is running then there is an issue with the Fuel Pressure Regulator. That is always on the return side of the injectors.
If the FPR the ONLY thing that hasn't been replaced.....
Click to expand...

You could certainly swap that between the engines without requiring medical attention for cuts and bruises.
 
I am not quite following the logic behind the FPR causing a loss of pressure at the rail, UNLESS the diaphragm was compromised, allowing fuel to run up the vacuum line into the intake plenum. And, if it's busted, wouldn't it stay busted instead of time (heat) related? Never the less, I'll check that first. Seems like I would have smelled or seen gas when I removed the plenum to check for injector o-ring leaks. There is no hint of gas anywhere around the engine. The FPR is in the Cool Fuel 2 enclosure, not on the rail like early models, so it's same level of effort as doing the HP pump. Finally, the hose from the FPR to the plenum is brand new.
This is the MEFI-3 version of the Cool Fuel 2 system. FPR is in the pump assembly, so same level of effort as changing the HP pump.
My tank gas is 3.5 years old. Even as rec fuel, I'm sure the combustion properties are gone, or severely reduced. Gonna have to throw away 200 gallons. So running off of known good tanks 6 gallons at a time. I don't want to be chasing ghosts that are bad fuel related, thinking it's something else.
 
370Dancer said:
I am not quite following the logic behind the FPR causing a loss of pressure at the rail, UNLESS the diaphragm was compromised, allowing fuel to run up the vacuum line into the intake plenum. And, if it's busted, wouldn't it stay busted instead of time (heat) related? Never the less, I'll check that first. Seems like I would have smelled or seen gas when I removed the plenum to check for injector o-ring leaks. There is no hint of gas anywhere around the engine. The FPR is in the Cool Fuel 2 enclosure, not on the rail like early models, so it's same level of effort as doing the HP pump. Finally, the hose from the FPR to the plenum is brand new.
This is the MEFI-3 version of the Cool Fuel 2 system. FPR is in the pump assembly, so same level of effort as changing the HP pump.
My tank gas is 3.5 years old. Even as rec fuel, I'm sure the combustion properties are gone, or severely reduced. Gonna have to throw away 200 gallons. So running off of known good tanks 6 gallons at a time. I don't want to be chasing ghosts that are bad fuel related, thinking it's something else.
Click to expand...

Looks like you are in for the pump replacement. Glad it is the port side. Simple enough given all the effort you have put in so far. Also.....I'm sure you have thought of this.....your gas cans are vented when you are running the engine? If they are not.....that could explain why it falls off consistently.
 
Verify part numbers, but this company sells the pump and the regulator (reuse the cooler). The genuine pump and cooler (no regulator) is about $830 from Mercruiser.

Free shipping and lifetime warranty. I used them before for ATV pumps. I couldn't tell the difference from OEM.

www.highflowfuel.com

QFS OEM High Pressure Fuel Pump w/ Regulator for Mercury Mercruiser, V6/V8 305/350/377/454/502 EFI, Replaces 861156A1, 807949A1, Sierra 18-35433

The Authority in OEM Quality and Affordable Powersports Replacement Parts. Shop with confidence. Guaranteed fit, backed by a lifetime warranty.
www.highflowfuel.com www.highflowfuel.com
 
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