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BF200 burning up fuel pumps $$$$

Skooter

Advanced Contributor
I have an '03 200 that has burned up 3 fuel pumps. I bought the motor used, so Im not sure if this was an issue before I got it. But since I got my hands on it, it has gone thru three fuel pumps. I have also replaced the vapor separator tank with a good condition used one. I have taken the bot out twice and both times I have had fuel pump failure. The scenario is like this: Saturday I was going fishing, (keep in mind I have a brand new high pressure Honda fuel pump), I start up my engine and within a few minutes the PGM-FI alarm sounds. If I turn the engine off and on it will clear up for a few minutes once again. If I run the engine, it runs great and alarm doesnt go off. Well, I have researched this problem and apparently its the O2 sensor...(Im not sure if the O2 sensor is related to fuel pump??) Anyways, I ran offshore for about 30 miles with not issues other than the PGM-FI alarm sounding when I idle. For that reason I had been turning on/off that motor when I was drifting or needed to idle. Well, now Im 35 miles offshore and that particular motor did not want to turn on. Sounded like it was out of fuel. I squeezed bulb and was soft (was able to squeeze it 2-3 times). Engine still did not start. I came back in to port on my other motor. Upon my arrival to dry land, i checked the fuel lines and had fuel going into the vaport separator tank. I took off the bolt on the starboard side to see if there was any fuel coming out with key turned on and nothing! I could hear fuel pump humming, but no spray of fuel. Im at a loss here and would apprciate any help. I had also replaced the fuel filter in the VST and the inline filter and water strainer prior to my trip.
 
A failed O2 sensor should not cause a fuel pump failure. You can easily check whether the O2 sensor has failed by shunting the service connector and counting the blinks on your MIL as described many times on this forum. A single blink, repeated about every 3 seconds indicates a faulty O2 sensor or faulty connection.

I assume you changed out the HP filter when you changed the pump, correct?

What immediately comes to mind is that possibly the float valve in the VST tank is sticking, causing the HP fuel pump to overheat and fail. I would pull the VST tank and HP pump, clean the VST again, check the float valve, and replace if any sign of scoring or sticking, then bench test the HP pump. If the VST passes the test, then back up to the low pressure pump. Again, if that fails, it will deprive the HP pump of fuel, and could overheat it. If you can get the motor running again, when the alarm goes off, try pumping the primer bulb rapidly. If the alarm goes off, that is a good sign that the LP pump has failed.

Another possibility is that the HP pump is misaligned on it's bracket, but it's hard to see how that would necessarily cause the kind of failure you are describing.
 
Thanks chawk man! This may sound strange, but on the previous "burned" out pump, looking at the top side of the pump where the pressured fuel exits, there is a small hole near the exit flow hole (near electrical connectors). I tested it and I stuck the lower end of the fuel pump into water and applied 12 volts to it. It pumped water out of the small hole, but not the large hole. Can u explain this?
 
I assume you are talking about the pump itself, and not the pump assemble (i.e. the "can" in which the pump sets.) I don't even see such a hole in my shop manual diagrams. I can only speculate that something inside the can is not assembled correctly, or is plugged up. You are going to need to tear it all the way down to see. Hope you have a Helm Shop Manual. The entire procedure is described starting on page 5-81, through page 5-93.
 
fuel pumps in general require fuel input. If there is no fuel input it will suck air in and that will cause it to heat up and eventually fail. If your pump still humming and no fuel come out you may have a clog somewhere in front of the pump. Check the float valve first and work your way back to the tank. GL.
 
A failed O2 sensor should not cause a fuel pump failure. You can easily check whether the O2 sensor has failed by shunting the service connector and counting the blinks on your MIL as described many times on this forum. A single blink, repeated about every 3 seconds indicates a faulty O2 sensor or faulty connection.

I assume you changed out the HP filter when you changed the pump, correct?

What immediately comes to mind is that possibly the float valve in the VST tank is sticking, causing the HP fuel pump to overheat and fail. I would pull the VST tank and HP pump, clean the VST again, check the float valve, and replace if any sign of scoring or sticking, then bench test the HP pump. If the VST passes the test, then back up to the low pressure pump. Again, if that fails, it will deprive the HP pump of fuel, and could overheat it. If you can get the motor running again, when the alarm goes off, try pumping the primer bulb rapidly. If the alarm goes off, that is a good sign that the LP pump has failed.

Another possibility is that the HP pump is misaligned on it's bracket, but it's hard to see how that would necessarily cause the kind of failure you are describing.

If the low pressure pump was bad, wouldn't I have noticed the motor surging when it was running?
 
Yes,normally,but this is an abnormal situation. You need to start at the fuel rail and work back to find the problem. Something is clogged up or not perfoming in your fuel delivery system. The lp pump is the last stop in the chain.
 
Okay, today I started investigating my fuel system. I had fuel in low pressure pump, and when cranked engine with outlet hose disconnected, it produced quitea bit of fuel. Also fuel solenoid seems to work (when I turn key, fuelcomes out of solenoid).All lines areclear of kinks or cracks and blew thru them to make sure free of debris. I pulled VST out and opened it up. It was approximately 3/4 full. I pulled electric pump out and tested it in water. Once again the fuel is comming out of the little hole, not big hole like it should.. I dunno if honda does this on purpose, like if pump gives out something plugs up big hole. Anyways, I am stumped! The only other thing I thought I could check is the voltage going into fuel pump. Should it be 12 volts?vst.jpg Also the float valve looked fine upon inspection
 
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Weird. Where are you getting the pumps? Could it just be a bad batch of pumps? If you are sourcing them from the same location, you might want to go somewhere else if possible.

I just opened an electric fuel pump up a while back so that I could free up the impeller and use it to pump old fuel out of a tank before installing it's replacement. I will see if I still have it lying around to see if I can figure out what could be going wrong with yours. Definitely should pump out the "big hole".

And, yes, 12 volts is a standard for "in tank" pumps.
 
Ditto Jimmy - this is weird. Are you sure you have the positive & negative hook-ups correct so the motor is running in the right direction?
 
Weird is right! Add the word FRUSTRATING too. I really appreciate you guys input. The pumps are OEM pumps.As far as I know the first pump was the "original" pump to my knowlegde. The 2nd pump I put on was from Ebay, I was able to find a whole VST and pump used, but in working order. It had been inspected and cleaned before selling. The last pump I put on was a brand new OEM Honda pump. I dont think the problem is in the VST because those have been switched out once. As for the polarity Im sure it's right.. Pump worked for about 3-4 hours then failed. I did some research last night and found a guy with the exact same problem as mine. Unfortunately no onehad replied to his thread except for me. http://forums.iboats.com/showthread.php?t=480531 Im going to check out the voltage today. Maybe its under volted and burning it out? Ive ordered a new fuel pump relay harness as well. Thanks again for your input on my challenging situation.
 
Skooter - one thought just occurred to me. There is a fuel line cutoff solenoid up stream from the fuel pump. Have you tested that? Could it possibly be de-activating and running the VST dry? Pull it, check the electrical connection, and see if the plunger is activating correctly when power is applied. Just a possibility. I've never fooled with it, so I'm guessing in the blind.
 
When I turn the key with hoses off the solenoid, it spills fuel out. So Im guessing its working fine. Im so frustrated..Im tempted to replace solenoid, low pressure pump, high pressure pump, vst float valve and see what happens. to my knowledge everything is functioning as it should, so Im chancing of wasting $$ and another burned fuel pump
 
Yes, but check the electrical connections to the solenoid to make sure they are clean and tight. If the connections are not constant, it is possible that an interim shutdown would starve the fuel pump and burn it out.
 
i know the internal ones are tight. as for the harness, I had zip tied it when I put new pump on, but maybe connector is loose..
 
UPDATE:

Today I checked the voltage going into the HP pump. With ignition on it measured 12.5 volts, when i cranked engine it was at 8.7 volts. Engine was cranking,not running. Is the voltage low?
 
Yep - sure is. Dropping to maybe 10.5 or 11.0 volts upon cranking should not be a problem, but I think 8.7 is entirely too low. If Jimmy or Mike say different, then take their advice. They know a hellava lot more than I on the electrical issues. When that happens, it is often a connector problem - often the ground wire. There is a ground terminal coming off your main relay (there is a 6-prong connector, a 4-prong connector, a 2-prong connector, and a separate ground wire). Check that ground wire for a good clean, tight connection. Also, check the spades on fuse #2 (10 amp) - that's your fuel pump fuse.
 
Great! I knew I'd make headway on this site..I had ordered a new fuel pump harness as part of my "preventative" maintenance, as my other honda had started cranking by itself and the culprit was a corroded fuel pump relay.. and I will replace that as soon as I get it in. thanks again and I will keep u updated.
 
I agree with chawk_man that the 8.7 volt reading is way too low but my next question is what is the voltage while running? Do me a favor and check the voltage at the cranking battery terminals while the engine is turning over and see if it is going low there as well. If so, you have a weak battery. If the voltage at the battery is staying up above 10.5 volts while cranking, then checking the voltage to the fuel pump while the engine is running would be the next logical step. Low voltage while running would certainly lead me to check all the power feed connections to the pump, of which there appear to be many.

Looking at your wiring schematic, there is a 2 pin connector at the main relay with a pink/red wire and a white/blue wire. The pnk/rd wire feeds directly to the pump connector. The wht/blu wire goes through a 4 pin connector and on the the fuse which, in turn is fed from a HOT AT ALL TIMES (HAT) stud terminal that also feeds two other fuses. I would want to verify each and every one of those connections.

The one connection you can't access is the set of points in the fuel pump relay that is housed inside the main relay assembly. It is possible that your voltage drop could be occurring there. You would need to probe the pk/rd wire of the two pin connector to verify that the proper voltage is being delivered across that set of relay points.

I have read several posts here where the main relay has given trouble with poor connections so that is a good item to eliminate as a suspect.
 
Professor Jimmy strikes again! Thanks for the detailed look-see, Jimmy.

Given Skooter's initial description, I'm suspecting a loose or corroded ground in there somewhere.
 
Best way is to shunt the 4-prong service connector as described many times in this forum...
Takeoff the engine cover and the plastic cover over the electronics on the front ofthe engine. There you will see a red four-pronged female plug. Use a paper clipto shunt the lime green/white wire to the black wire – that is, the two wiresthat are closest to the engine when the red service connector is correctly setin it’s holder. If in doubt, invest in a SCS service connector, which you canorder online. Part number 070PZ-ZY30100.
Onceconnected, turn on the key switch and observe the number of blinks on the checkengine (MIL) light. If the MIL comes on and stays on without blinking, you haveone of the following conditions:
• Short circuit in the service checkconnector wire
• Short circuit in the MIL wire
• Short circuit in the sensor systempower supply
• Open circuit in the power supply lineto the ECM
• Faulty ECM

Ifthe MIL comes on, then goes off after a few seconds, there are no codes in theEPROM.
Ifthe MIL starts blinking, then count the blinks, which will indicate the faultcode. You may get long blinks and short blinks. For example, two long blinks,followed by five short blinks, would be a fault code 25. The blink sequence will repeat itself until you turn thekey off. If there is more than one fault, you will get multiple fault codes.For example, three short blinks, followed by two long blinks and five shortblinks would be fault codes 3 and 25. Post the number of blinks and I will tryto tell you what the error code is. Or, send me an e-mail at [email protected]and I will send you the codes.

If you get only one blink, that repeats about every three seconds, that is afaulty O2 sensor. If a faulty O2 sensor is indicated, first check the wiringand connector. a loose or corroded connection can set off that alarm.

 
I agree with chawk_man that the 8.7 volt reading is way too low but my next question is what is the voltage while running? Do me a favor and check the voltage at the cranking battery terminals while the engine is turning over and see if it is going low there as well. If so, you have a weak battery. If the voltage at the battery is staying up above 10.5 volts while cranking, then checking the voltage to the fuel pump while the engine is running would be the next logical step. Low voltage while running would certainly lead me to check all the power feed connections to the pump, of which there appear to be many.

Looking at your wiring schematic, there is a 2 pin connector at the main relay with a pink/red wire and a white/blue wire. The pnk/rd wire feeds directly to the pump connector. The wht/blu wire goes through a 4 pin connector and on the the fuse which, in turn is fed from a HOT AT ALL TIMES (HAT) stud terminal that also feeds two other fuses. I would want to verify each and every one of those connections.

The one connection you can't access is the set of points in the fuel pump relay that is housed inside the main relay assembly. It is possible that your voltage drop could be occurring there. You would need to probe the pk/rd wire of the two pin connector to verify that the proper voltage is being delivered across that set of relay points.

I have read several posts here where the main relay has given trouble with poor connections so that is a good item to eliminate as a suspect.

Okay I checked voltage at battery terminals when cranking, it was 11.54 volts. So I know I am definitely having an issue, possibly ground like you guys have mentioned. But now my question is, could LOW voltage burn up my brand new pump after just 3.5 hours?
 
11.5 volts is a bit low during cranking, but not too low. Not sure of the exact operating range for that fuel pump motor, but should be 12 volts +/- about 1.75. But it's not just the voltage, it's also the amperage. It is not unusual to get the proper voltage reading, but a weak ground can cut down the amperage necessary for the motor to operate correctly. That is, there is too much resistence in the circuit for the 12 volts to generate sufficient current. A loose or corroded ground, or a corroded wire can cause that. (Hope that makes sense - It's been a long time.)
 
I was thinking about your question "could low voltage burn up my brand new pump"? I believe it could. The pump, needing northwards of 11 volts or so to operate at "design", would be almost "stalled" if only getting less than 9 volts. As a matter of fact, I'm surprised your engine ran at all since it would not be getting anywhere near the volume of fuel in needed.

So, with the pump turning slowly, there is amperage flowing and that will create heat. The pump uses the gasoline it pumps to cool itself internally. If little to no fuel is flowing through the pump but it is still energized, I believe it will eventually overheat and fail. Done in 3.5 hours? That I'm not sure about.

I started cutting apart that pump I have the other day and got sidetracked. But, after looking at it, I THINK that the little hole is for self priming. Since it is submerged, I think a little fuel flows through a small orifice at the impeller end, through the pump and then out through the hole in your picture all the time as a sort of "bypass air bleed". The fact that if ONLY comes out of there on your old pump is a sign that the pump just isn't turning fast enough to produce enough volume to have have it "gush" out of the big delivery orifice.

Unplug that two pin connector I mentioned above with the pnk/rd and wht/blu wires and see if you get more than 8.7 volts on the pnk/rd, with the key on, coming out of the main relay. If not, you need to solve that mystery.
 
Hi Skooter,
I finished hacking up that fuel pump (bosch) today and it is as I thought. That little hole is a bypass that allows the pump to purge air. If you still have the plastic housing that you cut off of yours, you can go back and look at the outlet nipple and see if you don't have a small, spring loaded check valve inside that nipple. I think they all do and the pump has to make enough flow and pressure to unseat that valve before any fuel will exit out that nipple. I'm guessing it is something on the order of 2 to 3 psi to unseat that valve. It is a tiny little spring.

I'm telling you all of this to illustrate just how bad of shape your pump is in if it can't even unseat that check valve. It's either that or some sort of debris is blocking the nipple.

Have you had a chance to check the voltage on the pnk/rd wire coming from the fuel pump relay inside the main relay yet?

Sorry if I'm bugging you but I'm just really interested now.
 
Yep - More and more this is sounding like a voltage problem. However, that's where we are looking, so don't be surprised if it is something entirely different. But I can't think of anything else at this point, outside of a flakey connection to the fuel cutoff solenoid. Keep plugging, ou'll find it.
 
Okay, i just got my parts in over the weekend...I pulled the screen that goes between the VST and fuel pump and this is what I found. How does this get past the 3 filters that I have on my boat? Also when I replace the plastic screen/fuel pump holder, should the hole on the bottom be aligned with one of the holes on the VST?sand fuel pump.jpg
 
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