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2001 Mercury 4 stroke 115hp fuel pump cutting out


Sawtyscott

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I am having some dramas with my Merc 2001 115hp 4 stroke that im hoping somebody might be able to help with.

I repowered my Seafarer with this motor last year, it only had 220 hrs on it but had sat around unused for along time. It went started & ran fine but seemed to run out of fuel at WOT, this seamed to be cured after I ran some Wurth injector clearer in several tanks of fuel. On occasion it would turn over but not fire after not being used for a week or two. I would remove the fuse cover & check the fuses(all ok) then it would start & run fine? Last time I took it out it did this again but then started but when running up the river at around 4000rpm it would just cut out and stall. I would then restart it only to have this happen again a min or tow latter. it then started to starve for fuel & then cut out & wouldnt restart. I then checked fuses (ok) and for any fuel leaks(none found) I then checked for fuel flow out of the low pressure pump (ok) & then for pressure at the schrader valve at the top of the fuel rail, no pressure found. I then removed the connector at the high pressure fuel pump and tested for power with my mate turning it over, the was no power feed. I then cut the wires to the connector & connected up jump wires straight to the power & earth at the starter. the high pressure pump now ran & the engine started. it then ran great like this at 4000 to 4400rpm for about 20mins then it seemed to stave for fuel again but did not cut out, it would only manage around 6knots at WOT the remainding 10 mins back to the ramp. I let it cool down for a couple of hours & reconnected the original wiring.  This is when I found it had power supply to the pump was there but no earth, if I bridge the earth out to the manifold the pump runs? 

At this stage I am planning on removing the high pressure tank assy to clean it out & replace the high pressure pump? & may be replacing the relays. I bought the motors as a pair so I have one as spares if needed.

Has anybody else had this with this model Merc or  the Yamaha of the same vintage?

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On a car I have had a fuse that looked fine but had a loose connection, chased my tail until I replaced it and bingo problem fixed.

did the fuel lines, bulb and connections get changed when repowering, the lines or bulbs might not be good enough when the high pressure pump kick in at over 4,000rpm.

just some thoughts 

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the high pressure fuel pump (vapour seperator) has a screen in the bottom that needs to be checked and cleaned.also when you turn key on to the first turn  beep stage you should hear high pressure pump start that will mean it is working .my bet clean vst  and check all fuellines and filters.also i have seen terminals rusty before on connection to pump clean and spray .i hope this helps regards dunc333

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On 11/23/2018 at 6:07 PM, dunc333 said:

the high pressure fuel pump (vapour seperator) has a screen in the bottom that needs to be checked and cleaned.also when you turn key on to the first turn  beep stage you should hear high pressure pump start that will mean it is working .my bet clean vst  and check all fuellines and filters.also i have seen terminals rusty before on connection to pump clean and spray .i hope this helps regards dunc333

Should all mercurys beep on startup?  Mine doesnt.  Ive seen a few people mention this in other posts.

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12 hours ago, dunc333 said:

please confirm this is a efi engine fishop

 

yes 2006 fourstroke efi 90hp.  Had a quick look at the service manual last night couldnt find anything about it.  Might have a better look next week when I have time.

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On 11/28/2018 at 10:15 AM, dunc333 said:

i believe so fishop i can say 100% yes from2003 onwards

Mine is a 1999 EFI 2-stroke and it beeps... the beep sounds at the gear/throttle control box where the ignition key is (not from the engine).

On 11/21/2018 at 10:54 AM, Sawtyscott said:

This is when I found it had power supply to the pump was there but no earth, if I bridge the earth out to the manifold the pump runs?

Do you have access to a Mercury workshop manual for your motor?  I googled for mine and found a PDF downloadable version - you may be as lucky.  If I scan my manuals EFI troubleshooting page this is what it shows:

image.png.3b4b8173ff8684b7bd5a6132888cfbc1.png

So assuming yours is similar, and you have proven your fuel pump runs when you bypass the ECM and direct wire it - it starts to point to the ECM ....the ECM takes its input from the Air Temp Sensor and Water Temp Sensors.... and reading the maunal its says it adjusts fuel flow ... could explain why yours starts when it cools down ...then goes into limp mode after running at 4000rpm etc.

image.png.e112c766e51648fad081c74b354ccd05.png

I'd suggest to try and get your hands on a manual for your motor as the first step. I feel the only way to get to the bottom of this would be to follow the diagnostic procedures and go through the prescribed process of elimination. Usually with an intermittent problem - your pretty much relying on finding something not working within spec. 

Cheers Zoran

Edited by zmk1962
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On 11/22/2018 at 8:04 AM, Sawtyscott said:

Thanks Jeff, that is going to be my 1st thing to try this weekend, new fuses & relays. It did get new lines but not a new bulb so I might shout it one too. If those two thing dont work I am going to rebuild the fuel pump assy. 

If your having trouble finding a manual online I ended up getting mine from a mercury dealer who ordered it for me from the US.  Be careful though, some dealers will say they cant order them, probably to force you to take it to their shop to get fixed.  I had to go to Motor Marine in Townsville who happily ordered my manual from the US and then posted it to me down in Whitsundays.  

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  • 2 weeks later...

Thanks for helpful info guys. The new gaskets for the vapour seperator landed today so thats the 1st thing to service this weekend, along with new filters. Then some testing in the river as I can not get it to play up on the ears. I have a spare ecu, relay & air temp sensor to swap out if needed. 

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  • 3 weeks later...
On 11/28/2018 at 9:15 AM, dunc333 said:

i believe so fishop i can say 100% yes from2003 onwards

So finally pulled control box apart and found the buzzer.  Connections looked ok.  Can i just plug this buzzer into a 12v power supply to test if it will work?  

 

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34 minutes ago, Fishop said:

So finally pulled control box apart and found the buzzer.  Connections looked ok.  Can i just plug this buzzer into a 12v power supply to test if it will work?  

 

Or is there another way to test the buzzer say by removing the temp sensor plug while the ignition is on/engine is running?  Should that cause the buzzer to sound? 

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  • 3 weeks later...
On 12/27/2018 at 6:02 PM, dunc333 said:

yes or 12volt should do it i would think .my money is on faulty beeper.

So buzzer works fine when connected to a 12 volt power supply.  Yet I do not have any start-up warning sounds.  Is it possible my model does not have this function?  Is there another way to check the buzzer circuitry works correctly? 

Ie can I start the engine and remove the water temp sensor plug while engine is still running?  Should this cause warning buzzer to operate?   I'd like to make sure any warning signals are all hooked up and operational. 

Edited by Fishop
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yes you can pull sensor wire while running if still no beeps try pull oil pressure sensor ,if still no good check wiring  to ecm look for same wire as going to buzzer pull plugs from ecm and inspect and spray with inox .

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  • 2 weeks later...
On 1/12/2019 at 1:13 PM, dunc333 said:

yes you can pull sensor wire while running if still no beeps try pull oil pressure sensor ,if still no good check wiring  to ecm look for same wire as going to buzzer pull plugs from ecm and inspect and spray with inox .

Pulled water temp sensor, no alarm.  Oil sensor is screwed on so didn't touch it.  Wiring diagram is hard to read/understand.

Picture is of gauges wiring.  Buzzer is number 11.  Brown/blue wire goes through tacho harness and on to 18 which is a warning light which I don't have equipped.

Purple wire connects to ignition which then goes on through tacho harness and to connect to 13 which is temperature gauge.  I don't have a temp gauge.  Could this be why I don't hear a beep on start-up and when I pull the temp sensor?

 

Might have to try by disconnecting the oil sensor wire next which is a single pink/white wire connected on top of engine just under fly wheel.  

1547977005963585.jpg

Edited by Fishop
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  tell me if im wrong looking at my book tan with light  blue  goes to ecm ,purple goes to key switch .check both sides with a test light for power when keys is turned to first position .run aligator clip on test light straight to battery negitive terminal  then check the two wires process of illimination .1 you have confirmed horn is good so now you have to find the culprit wire

Edited by dunc333
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