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mtnbkr738

Fuel Pump Relay /Schematic for '89 Sunsetter/Monsoon

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mtnbkr738

Hi All,

my fuel pump is intermittently cutting out (brand new pump). the test light on the fuel pump keeps shutting off when at higher RPM with a warm engine. (only does this after engine is well heated up). Test light goes on then off then on then off... of course the motor then stutters and shutters trying to run.... then it will run fine for ten minutes or whatever.

Im trying to find a Schematic or something to tell me WHAT relay powers the fuel pump.... so i can track this down. I dont want to buy a new ECM unless i can prove thats the problem.

VIDEO of test light cutting out and you can hear the engine.

 

ANY HELP is appreciated.

 

 

Edited by mtnbkr738

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tvano

there are three relays located near the ecm (on my '04), i'd guess yours is similar.

those relays are ignition, starter and fuel pump and are all alike so feel free to swap them out to see if the symptoms move with the fuel relay.

pm sent.

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minnmarker

Check the oil pressure and/or temp sensors - the ones that do not send signals to the gauges.  You're may only have the oil pressure sensor.  They are in series with the fuel pump and will cut power to it if they're defective or the connections are loose or corroded.  Of course, first make sure that you don't have an actual oil pressure or temp problem.

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mtnbkr738
10 hours ago, tvano said:

there are three relays located near the ecm (on my '04), i'd guess yours is similar.

those relays are ignition, starter and fuel pump and are all alike so feel free to swap them out to see if the symptoms move with the fuel relay.

pm sent.

Thank- thx for photo.. My setup is alittle different.. I found the 3 fuses but I couldn't find the 3 relays like what is shown in your pic.... Yes I would like to switch the relays to play with them... I'll send a picture tomorrow. Thx!

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mtnbkr738
On August 18, 2016 at 10:26 AM, tvano said:

there are three relays located near the ecm (on my '04), i'd guess yours is similar.

those relays are ignition, starter and fuel pump and are all alike so feel free to swap them out to see if the symptoms move with the fuel relay.

pm sent.

Ok I swapped the relays. Still same problem. Again... Only after boat heats up 10 minutes or so of driving.... If I pop open the dog house and let it cool for 10 minutes, then I'm good to go for another 10 minutes.... So it only happens when hot..

Any other ideas? 

Anyway to find out what other things would cause the ECM to shut down the fuel pump? (Except...the fuel pump isn't totally cut off... It's like a short... It's on and of and on and off like in video)

 

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minnmarker

Bypass the temp sensor that's in series with the fuel pump. See post above. If it fixes problem then replace. Cheap part. Do this only if you're getting normal readings on the dash temp gauge.

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mtnbkr738
7 hours ago, minnmarker said:

Bypass the temp sensor that's in series with the fuel pump. See post above. If it fixes problem then replace. Cheap part. Do this only if you're getting normal readings on the dash temp gauge.

Hi Mark, how do I by pass the temp sensor? Just unplug it, or do I need to put a jumper between the two wires on the plug?

Also- I'm guessing temp sensor is up by thermostat- correct?

-- I'm not much of a tech- :)

thx

Edited by mtnbkr738

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electricjohn

First off, I am assuming you have an EFI engine.  The fuel pump relay is the only one with a green wire connected to it.  There should also be a red or pink wire that will be connected to the relay too and be the same thickness as the green wire (actually green with a white stripe).  You have to be sure that this red or pink wire is live (+12volts) any time the key is on.  The green wire is connected to ground(-12volts) by a switch in the ECM and this is how the relay is turned on. 

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mtnbkr738
13 hours ago, electricjohn said:

First off, I am assuming you have an EFI engine.  The fuel pump relay is the only one with a green wire connected to it.  There should also be a red or pink wire that will be connected to the relay too and be the same thickness as the green wire (actually green with a white stripe).  You have to be sure that this red or pink wire is live (+12volts) any time the key is on.  The green wire is connected to ground(-12volts) by a switch in the ECM and this is how the relay is turned on. 

Yes efi... I will check this. Thx!

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mtnbkr738
23 hours ago, minnmarker said:

Bypass the temp sensor that's in series with the fuel pump. See post above. If it fixes problem then replace. Cheap part. Do this only if you're getting normal readings on the dash temp gauge.

Mark, can you tell me where the temp sensor is?

ED66D310-9DB5-4B37-98B8-0EC4604524BD_zps

 

5956DA1E-D8EB-40C2-90DD-737F2367A3A9_zps

CEA1A567-285C-4949-BD2F-5E479303DC0F_zps

Edited by mtnbkr738

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minnmarker

3rd pic just to the right and below the word Malibu. In earlier post I assumed you had a carb. With efi you probably will have only one temp sensor. 

Are your temp and oil pressure gauges reading normal when this happens? What rpm?

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mtnbkr738
1 hour ago, minnmarker said:

3rd pic just to the right and below the word Malibu. In earlier post I assumed you had a carb. With efi you probably will have only one temp sensor. 

Are your temp and oil pressure gauges reading normal when this happens? What rpm?

Temp is at 160

oil pressure moves around a lot depending on rpm.but is not or never at zero.

Problem does NOT occur at a specific rpm... It seems like when the problem starts to happen, it happens all the time --- the above video is kinda a "tame" version of what is happening.... Again.. It's seems random.  

Last night it happened at idle speed...I barely made it back to the dock.... Then I could get up to 2k rpm and cruised back...

How do I test this..... DO I disconnect those wires on the temp sensor?... DO I need to Jump those connectors after I disconnect it??

thx!

 

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minnmarker

You may just have an electrical gremlin. Try disconnecting every wire harness you can find, spray some contact cleaner on each end and reconnect. Then check every ground by lossening it checking for corrosion and tightening. I assume by oil pressure all over the place you mean it gets steadily higher with rpm.  If the needle is actually moving around when you're at a steady speed then you need a new oil pressure sender.

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mtnbkr738
On 8/22/2016 at 11:43 AM, minnmarker said:

You may just have an electrical gremlin. Try disconnecting every wire harness you can find, spray some contact cleaner on each end and reconnect. Then check every ground by lossening it checking for corrosion and tightening. I assume by oil pressure all over the place you mean it gets steadily higher with rpm.  If the needle is actually moving around when you're at a steady speed then you need a new oil pressure sender.

Mark,

1) i disconnected EVERY connection i could find, sprayed cleaner, reconnected.

2) looked for any broken wires

3) disconnected and cleaned and re tightened every ground i could find.

4) temp stays at 160

5) oil pressure is consistent when at consistent RPM

6) Boat runs PERFECT FOR 30 MINUTES this morning.

7) then the problem starts. - seems like problem starts AFTER i shut off for a few minutes while we switch skiers

8) fuel pump keeps losing power - rpm makes no difference... its on and off and on and off at any rpm.

9) if i wait and let engine cool down, then i can maybe get another 20 minutes of perfect running before issue starts again.

10) i DID disconnect temp sensor plug as discussed above... problem did NOT go away.

 

Any more ideas??

THX!!

 

 

 

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minnmarker

Are you sure the electrical power going to the pump is being interrupted?  Maybe you have vapor lock? #7 above suggests that.  First try running the blower full time and see if that cures it.  If so it's vapor lock and there are lots of threads on that.  You could also prop open the engine cover to keep it from getting hot under there.  If those fail my next step would be to wire the fuel pump directly to the battery with a switch in the hot leg.  Leave the switch off (open) until you have the problem then turn the switch on right away without shutting off the engine.  If the problem goes away then you know you have a problem in the circuitry somewhere.  If it doesn't, and you have ruled out vapor lock, then your pump, or something else, is going bad.

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mtnbkr738
18 hours ago, minnmarker said:

Are you sure the electrical power going to the pump is being interrupted?  Maybe you have vapor lock? #7 above suggests that.  First try running the blower full time and see if that cures it.  If so it's vapor lock and there are lots of threads on that.  You could also prop open the engine cover to keep it from getting hot under there.  If those fail my next step would be to wire the fuel pump directly to the battery with a switch in the hot leg.  Leave the switch off (open) until you have the problem then turn the switch on right away without shutting off the engine.  If the problem goes away then you know you have a problem in the circuitry somewhere.  If it doesn't, and you have ruled out vapor lock, then your pump, or something else, is going bad.

Mark

i will try your "hot wire" idea .

QUESTION... is it SAFE to have the "hotwire 12v" line powered to the fuel pump WHILE the existing 12v power is STILL connected to the fuel pump (ie having 2, 12v power supplies going to the pump at the same time).  

thx!

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Kmfish87
2 hours ago, mtnbkr738 said:

Mark

i will try your "hot wire" idea .

QUESTION... is it SAFE to have the "hotwire 12v" line powered to the fuel pump WHILE the existing 12v power is STILL connected to the fuel pump (ie having 2, 12v power supplies going to the pump at the same time).  

thx!

Shouldn't be a problem, just make sure to put an in-line fuse in the wire close to the battery to prevent any short circuits.

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minnmarker

And make sure you have your + and neg straight. If you do the pump will not notice any difference.

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MadMan
21 hours ago, mtnbkr738 said:

Mark

i will try your "hot wire" idea .

QUESTION... is it SAFE to have the "hotwire 12v" line powered to the fuel pump WHILE the existing 12v power is STILL connected to the fuel pump (ie having 2, 12v power supplies going to the pump at the same time).  

thx!

If you leave the existing wire connected, it will back-feed the circuit, bypassing the ignition switch.  This would keep the engine running even when the ignition switch is turned off.  Won't really hurt anything, just be aware of it.

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Kmfish87
3 hours ago, MadMan said:

If you leave the existing wire connected, it will back-feed the circuit, bypassing the ignition switch.  This would keep the engine running even when the ignition switch is turned off.  Won't really hurt anything, just be aware of it.

Shouldn't back-feed if he wires straight to the fuel pump. If the relay is bad, not getting power, etc [relay not closed] then the power would only go to the pump and wire up to the relay but not past the relay.

right?

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mtnbkr738
On 8/21/2016 at 8:34 AM, electricjohn said:

First off, I am assuming you have an EFI engine.  The fuel pump relay is the only one with a green wire connected to it.  There should also be a red or pink wire that will be connected to the relay too and be the same thickness as the green wire (actually green with a white stripe).  You have to be sure that this red or pink wire is live (+12volts) any time the key is on.  The green wire is connected to ground(-12volts) by a switch in the ECM and this is how the relay is turned on. 

Hi All

I FINALLY got out to test this today.

here is update:

  1. I have to run the boat skiing or tubing for 40  minutes for this "intermittent fuel pump shut off" issue to happen
  2. This problem will NOT duplicate itself with the boat idling in my driveway for nearly 1 hour.
  3. When the problem showed up again today (just like video above) i did put a 12 v test light on the PINK wire of the fuel relay
  4. the pink wire DOES have CONSISTENT 12 volts (the test light never flickered)
  5. with the relay in my hand, i could feel it clicking, on -off -on -off etc... and every time it clicked, the fuel pump would shut off and then when it would click again the fuel pump turned back on. 
  6. The delay of the on-off-on-off was about 1 second each... so the motor never shut off, just ran-hesitated-ran-hesitated etc
  7. so i would have to ASSUME that the ECM is shutting off the negative (turning off the fuel pump relay) intermittently

Any suggestions of what i could test or trouble shoot now???

Thanks!!

 

 

 

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tvano

re intermittent: if you gently flex the wires, while holding that relay and feeling it cycle, can you get it to become stable?

is there any reason not to meter the green wire from the ecm?  i'd be very comfortable w a digital multi-meter.  $10 if you don't have on in the tool box.  a must have.

not sure i'd recommend using a test lamp but if the ecm is sinking enough current to pull that relay i'd think it might be ok.  could be a big price to pay for a mistake should the ecm cough, though.

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mtnbkr738
3 hours ago, tvano said:

re intermittent: if you gently flex the wires, while holding that relay and feeling it cycle, can you get it to become stable?

is there any reason not to meter the green wire from the ecm?  i'd be very comfortable w a digital multi-meter.  $10 if you don't have on in the tool box.  a must have.

not sure i'd recommend using a test lamp but if the ecm is sinking enough current to pull that relay i'd think it might be ok.  could be a big price to pay for a mistake should the ecm cough, though.

1) I did flex the wires

2) I did swap out relays with the starter relay... I figured no way both could be bad (or could they????)

3) I did disconnect EVERY connection I could find, and spray clean them w electrical cleaner and check and inspect for cracked wires or bad connectors (even all connections under the dash.

4) I did loosen, clean and retighten every ground I could find on the boat.

5) I do have a meter, and yes I can check for continuity between grounds on the green wire.... But I would THINK that of course the ECM is killing the ground... (I.e. Turning the relay on and off) What else would be making the relay click on and off like that. (Except a bad relay like in statement #2 above) (right???)

6) Any other reasons the ECM could be turning off the fuel pump?? Maybe there is a bad sensor somewhere else telling the ECM there is another problem and the ECM shuts off the fuel. How do I find out what others sensors are connected to the ECM/ fuel relay???

 

thx!!

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minnmarker
1 hour ago, mtnbkr738 said:

6) Any other reasons the ECM could be turning off the fuel pump?? Maybe there is a bad sensor somewhere else telling the ECM there is another problem and the ECM shuts off the fuel. How do I find out what others sensors are connected to the ECM/ fuel relay???

Oil pressure and temp.  Could be bad sensors or bad connections or grounds (threads).  With the intermittent symptoms most likely the connections or wiring between sensors and ECM.

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testboat

Check for debris in the transmission cooler.  I worked on a boat that had pieces of old impeller stuck in the transmission cooler.  The gauge on the dash did not show an overheat condition, but the ECM was limiting power.  The ECM uses a different temp sender in a different location than the dash gauge.  

 

 

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