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2002 BF225 Intermittent Power Loss and Bucking

Eleazar88

New member
Hey All,
I'm chasing a dragon on this one and could use some more heads.

Symptom:
My 225 runs great and strong at idle, always starts right up, and will run strong under 2,000rpms. However if I push it above 2,000rpms it'll run for a while, never an exact amount of time, sometimes 10min other times 2min, at which point it will begin losing power and bucking as though fuel starved or vapor locked. It doesn't stall but just shakes and bucks. I come off throttle into neutral and then I can only push up to a slow "idle speed" in gear...about 1,000 to 1,200rpms. Strange thing happened the last time I went out. I had moved the primer bulb from between the racor and motor up to my center console (which put it between the fuel tank and racor). When I was running at 3,000rpms the motor did the same thing it had been doing but also stalled out completely. Upon inspection I found the cup attached to my racor had "popped" off. I screwed it back on sqeezed the primer bulb until primed and got under way again...less then five minutes later the same thing happened. The cup had no visual defects and once I replaced it it screwed on very well hand tight and had no leaks when running at idle or low speeds...I'm guessing some sort of back pressure build up causing it to "pop" after moving the primer bulb check valve closer to the tank as opposed to after the racor causing the racor to take the pressure? I'm lost on this one.

Interventions:
-Pumped fuel from tank and replaced with clean fuel
-Breather tube operates properly
-Drained VST, Removed and visually inspected for sediment (Float appeared to operate smoothly)
-Cleaned HP Pump Screen (no sediment found and appeared to be clean)
Replaced:
-all fuel lines from tank to LP pump (including those in the motor)
-Primer Bulb
-Racor
-LP & HP Filters
-LP & HP Pumps
-Spark Plugs

The Motor is very clean and has little corrosion. I've also inspected the vacuum lines and have found no deficiencies. the Diaphragm that sits above the vacuum canister (for the intake) operates properly. and there are no fuel leaks in the housing (Know very well how easy it is to "cut" the HP screen O-ring on install...went through a couple of those).
 
Sounds a lot what i experienced, finally did a compression test and checked the valves. (COLD). Found they were all off. Adjusted them and now motor is running like a champ.
 
Yes, by all means do a compression test and adjust valves.

BUT - your description indicates a fuel flow problem. I've never heard of a Racor filter bowl popping off, so that makes me very suspicious that you may be drawing air into the fuel line and that Racor filter could easily be the culprit. When your fuel pumps are pulling in fuel at higher rpm's, that puts a lot of suction on the lines and can draw air in through any compromised connection or seal, such as the seal that the Racor fuel bowl sits in or the seal where the Racor filter mates to the filter base.

To test, substitute a clear plastic fuel line to the onboard fuel/water separator, run the engine until it acts up and have someone watch that plastic fuel line for air bubbles. Alternatively, simply replace the entire Racor filter and base, making sure that the fuel hose connectors are correctly installed, tightened and sealed.

If that doesn't help, run that clear plastic hose from the LP fuel filter to the LP fuel pump and check for air bubbles. If none there, then I have not diagnosed the problem correctly.
 
Thanks for the replies fellas. This has certainly been a test of my mechanical skills. I'm hoping to get a chance to put some more work on the engine this afternoon...I will keep you posted on any progress/updates

CHawk, those were also my thoughts, one thing I failed to mention is that after it began "knocking" the filter bowl off I bypassed the racor altogether using an extra (New) primer ball I had on board...same symptoms presented themselves (which seems to a motor internal fuel flow issue as opposed to anything on the LP side since at that point I had replaced every piece of the system in front of the LP pump.

Also, as far as compression goes and please correct me if I'm wrong, but I've never known of any engine to operate smoothly in all RPM ranges that has low compression or compression issue in one or multiple cylinders. I can certainly do a test, but I've always kinda gone off the low tech assumption that if the motor runs strong and smooth it's safe to assume compression is within the correct range.

One "epiphany" I may have had is that I think there may be a possibility the Fuel Line Cut Valve is failing to open (or receive signal to open) when the motor tops 160 degrees...this is my only other logical explanation for the back pressure knocking the fuel bowl. Other idea was perhaps my buzzer failed and I'm getting a high temp first stage shutdown...this is a far reaching thought but easy enough to check. Any thoughts?
 
Eleazar88 - Roger that on bypassing the Racor. If that didn't help, then I was parking up the wrong tree. Still, I would run that clear plastic line from the LP filter to the LP fuel pump just to eliminate any possibility that you are getting air in the fuel lines.

I hope you have a shop manual. If not, here is a link to an older (European) one (that includes the BF 175.) There is not much that has changed.

http://planbmarine.com/wp-content/u...ice-workshop-and-repair-BF175A-BF200A-BF2.pdf

It's in PDF format and you can save it to your computer - it's about 22 MBytes. If you scroll down the left side, there is a text search box which is very useful.

The reason I'm sending that is that it provides some good diagnostics (starting on page 5-58) and gives you instructions for testing the fuel cutoff - see page 5-71. It's a simple resistance test between the two wires coming from the solenoid. It should be between 42.2 and 58.3 ohms.

And you are correct about the valves - typically valves out of adjustment show up as a rough idle.

You did not mention that you were getting an alarm, so I assume you were not. BUT, I would try to pull fault codes anyway just to see if anything is showing up. Fault codes are on page 5-14 and 5-15.

If you are getting high temperatures, the engine will go into SLOW mode (1800 rpm) and shut down in 20 seconds if it is not cured.

Is there any possibility you can beg or borrow another working ECU?
 
CHawk: I've been using a pdf manual on my phone but hadn't figured a good way to trans to my comp so appreciate the send.

The overheat shutdown was just an after thought guess I have not had any alarms and water pump pressure is good...just straining my brain to think of something. However everything I know about engines still points toward some sort of fuel starvation issue.

I tested the Fuel Line Cut Solenoid polarity last night...resistance was good. Applied 12v power and the solenoid opens as it should. I was thinking that there could be either a short between the solenoid and ECM, however last night I attached a red LED light to the solenoid terminal and when I turn the ignition to "run" or "on" the light came on for 2seconds (thus operating correctly). Next would be to confirm the solenoid receives signal to open when motor temp reaches 160+. That's also why I plan to check continuity and signal to the overheat sensors as it's my understanding they (along with the ECM) operate the signal to the Cut Solenoid.

As far as checking fault codes goes, I only have the two light side mount control model for my motor (oil pressure and overheat)

Unfortunately no spare ECU sitting I can get hold of.
 
FRAGO to my last msg:
Today I tested all the overheat sensors (ecu power/signal and continuity through various temps cold start/running at idle. All checked out.

Fuel Line Cut Solenoid operates through full range of tests however I can't test whether or not it opens under prescribed conditions (140+ degree temp/ correct speed and load)

I shorted the overheat sensor connectors with .1k OHM load resistors to simulate extreme overheating conditions. When I did this the motor operating as designed and shutoff after 20seconds so that system is operating as designed, however there was no audible alarm sounded. I found the previous owner had cut the wires to the buzzer...fixed that. Most likely a stand alone system that would not affect the Fuel Cut Solenoid but I'm just chasing the rabbit holes here.

I decided to inspect the VST again. I measured the tolerance of the shut off valve float and found it was 2mm out of spec. I adjusted to the opposite end which will put the fuel level in the VST at the highest point within tolerance as opposed to just outside the lowest lvl that it was at...if you're tracking what I'm saying here lol. I'm estimating that I should get an additional 1/4 to 3/8 higher fuel lvl within the vst. I'm not sure if this was actually contributing to the overall issue, but seeing as it presents like fuel starvation every little bit may help.
I'm going to get it on the water tomorrow afternoon

I'm hoping to get it on the water for a test tomorrow. I'll also connect a clear tube on the LP side so I can watch for bubbles as you've suggested.

Any chance anyone knows what sensors "talk" to the ECU in order to activate the Fuel Line Cut Solenoid for load and speed? I can't find it in the manual or any wiring diagrams.
 
That last is an interesting question and I do not have a definitive answer. However, the Helm shop manual says that "Fuel cut solenoid valve is controlled according to engine temperature, speed and load to prevent vapor locking of low pressure fuel pump."

Pull up that manual I sent and read the first ten pages of Chapter 18 to understand how it all operates. See especially page 18-4.

As a side note, it probably took me 4 or 5 years after I received my shop manual to get around to reading Chapter 18. That should have been the first chapter I read.
 
Update:
The plot thickens, finally had an afternoon to finish getting things back together and got her on the water for a test run. She ran for about 15-20 minutes before exhibiting the same symptoms...decreased speed/power loss, engine bucking/shaking, with a new occurrence...continuous audible alarm. Soo...my understanding is that a continuous alarm coupled with a reduced speed can only equate to either low oil pressure or overheat...is that accurate? Only other thing I'm aware of would be the overrev limiter but I'm not familiar with how that one presents. Nonetheless, I had a mechanic fail (because I was slightly distracted with a kiddo on board) but I don't recall what the lights were doing. I had previously tested the overheat sensors...they are good. I pulled the thermostats, starboard side was stuck half open and port side seemed to operate fine however there was a good amount of calcification around the thermostat. I've ordered replacements. For good measure I checked the oil level. It was just below halfway on the dipstick...not ideal but not terrible enough to cause a low pressure alarm I don't think...still...I'm going to change the oil filter and replace the oil to give it some good stuff and make sure it's all up to par. On an unrelated note, as I got to the boat ramp one of my timing belt idle pulleys began to fail. No damage caused as I was able to diagnose and shutdown before it reached complete failure...downside is the new pulley won't be in until thursday, but that'll give me time to get everything else done before the next test run. At this point I'll have replaced half the engine before actually sorting out the initial issue lol.

Keep you posted.
 
You are correct on what causes an automatic power down - overheat, which will shut down the engine in 20 seconds if not cured, and low oil pressure, which will not shut down the engine. So, you need to check the oil pressure. That requires a special fitting. Here is a post that Ian put up a while back:

"Use a mechanical gauge to see what your oil pressure is doing before you destroy your motor. You need to make or buy an adapter to fit where the large 22mm plug is on the vtec solenoid. You should have 80-90 psi at idle with a cold engine, once properly warmed up, that is after about 20 min hard run. the oil pressure should hold at 70 psi plus over 2000 rpm and 25 psi at idle."

BTW: Folks in this area (Chesapeake Bay), including me, are using Merc 25W-40 FC-W in their big Honda's. It's a bit thicker and seems to provide better lubrication, especially when the motor sits up for extended periods of time.

Recognize that there is a third heat sensor - the block temperature sensor - that sits in the V of the engine. That's also where the high pressure and low pressure oil sensors are located. You must remove at least one of the heads to get to them.

Do you have any idea why the timing belt pulley failed? Could that be the source of your problem - intermittent messed up timing?

My strong recommendation is that you find someone with the Dr. H diagnostic system and hook it up to see what you are really dealing with.
 
Hey All,
I'm chasing a dragon on this one and could use some more heads.

Symptom:
My 225 runs great and strong at idle, always starts right up, and will run strong under 2,000rpms. However if I push it above 2,000rpms it'll run for a while, never an exact amount of time, sometimes 10min other times 2min, at which point it will begin losing power and bucking as though fuel starved or vapor locked. It doesn't stall but just shakes and bucks. I come off throttle into neutral and then I can only push up to a slow "idle speed" in gear...about 1,000 to 1,200rpms. Strange thing happened the last time I went out. I had moved the primer bulb from between the racor and motor up to my center console (which put it between the fuel tank and racor). When I was running at 3,000rpms the motor did the same thing it had been doing but also stalled out completely. Upon inspection I found the cup attached to my racor had "popped" off. I screwed it back on sqeezed the primer bulb until primed and got under way again...less then five minutes later the same thing happened. The cup had no visual defects and once I replaced it it screwed on very well hand tight and had no leaks when running at idle or low speeds...I'm guessing some sort of back pressure build up causing it to "pop" after moving the primer bulb check valve closer to the tank as opposed to after the racor causing the racor to take the pressure? I'm lost on this one.

Interventions:
-Pumped fuel from tank and replaced with clean fuel
-Breather tube operates properly
-Drained VST, Removed and visually inspected for sediment (Float appeared to operate smoothly)
-Cleaned HP Pump Screen (no sediment found and appeared to be clean)
Replaced:
-all fuel lines from tank to LP pump (including those in the motor)
-Primer Bulb
-Racor
-LP & HP Filters
-LP & HP Pumps
-Spark Plugs

The Motor is very clean and has little corrosion. I've also inspected the vacuum lines and have found no deficiencies. the Diaphragm that sits above the vacuum canister (for the intake) operates properly. and there are no fuel leaks in the housing (Know very well how easy it is to "cut" the HP screen O-ring on install...went through a couple of those).


Howdy All.
I have had this problem for a wee while, and i seem to have cured it.
Under each head are poppet valves, these open and allow extra water through the motor as the revs get up. On my bf 130 i had an issue with salt buildup under the rubber seat/grommet in the poppet valve, so i decided to check these in the 225 despite being told they dont give trouble. They both had salt under the rubbers that was crimping the rubber on to the plastic valve and effectively jamming it. I removed the rubbers, cleaned them and refitted with some silicone grease under the rubbers to hopefully keep the salt out. Since then i have not has the alarm or surging. At least 10 hours of intermittent running.
Hope this helps
Dave.
 
Big Dave - thanks for the input. So, were you getting an overheat alarm?

Anyone reading this should note that the cover to the poppet (AKA pressure relief) valve has three bolts. But you only need to remove the two outside ones to remove the valve. The third one, in the back, next to the block, only holds the two halves of the valve assembly together. I learned that lesson the hard way. The shop manual is confusing on that issue.
 
Big Dave - thanks for the input. So, were you getting an overheat alarm?

Anyone reading this should note that the cover to the poppet (AKA pressure relief) valve has three bolts. But you only need to remove the two outside ones to remove the valve. The third one, in the back, next to the block, only holds the two halves of the valve assembly together. I learned that lesson the hard way. The shop manual is confusing on that issue.

Correct, I was getting an overhead alarm, being and light showing on the remotes.
 
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