Oil pressure switch / oil pressure sender

[Kwanza]

Hi all,
I am investigating previous sudden and clean shutoffs of my VP 3.0 GLP engine. Initially, I suspected fuel pump being shut down by a struggling alternator and a potentially failing bilge blower, this latter knocking down both dashboard and multimeter voltage reading from 14V to 12V while running, or from 12V to 10V on the ON position. This bilge pump has now been replaced, with both dashboard, multimeter and Garmin Striker voltage showing ~13.9 - 14.3 V while cruising at ~2800-3000 RPM; with bilge blower, if turned on, dropping voltage by less than 0.5 V.

I now suspect that my oil pressure safety switch might be the culprit.

Few days ago, I returned from an ~8 km trip, running smoothly at ~3000 RPM. Took boat home and parked it in driveway, then attempted to rinse the engine, but it would not start. This was approximately 30 minutes after shutting engine down. I was hoping that a potentially overheated oil safety switch or fuel pump relay are playing up and would start later.

I've tried starting a few times since, to no avail. Lanyard safety switch on, and there is spark.
Trying to listen to fuel pump humming is difficult, as I have a default continuous alarm while on the ON position.
Firstly, I need to know which one of A and B is the oil pressure gauge sender, and which one is the oil pressure safety switch (that could potentially disable my fuel pump). Wire color on A is blue, on B is light brown.

My gauge usually indicated between 20 - 40 PSI oil pressure. As I now attempt to start, and engine keeps turning over but not starting, oil gauge works up to same ~40 PSI over the ~5 seconds I attempt the start.
I did bypass what I thought was the oil pressure safety switch, connecting B to C. Still no start.

Resistance measurement values are:
Between B and C (or between B and other ground points): 4 Ohms, with brown wire on or off the spade.
Between A and C (or between A and other ground points): 252 Ohms when blue wire removed from threaded stud, 144 Ohms with wire on.

Are these values indicating anything
Single engine, single sender.

Any suggestion as to what to try next is welcome.
Thank you.

 

[Scott Danforth]

A is your gauge sender. It only controls the gauge
B is the wire off the oil switch
C is the oil fitting for the oil switch

The switch between Band C is a binary mechanical pressure switch

Your measurements are meaningless

You should be looking for a bad connection, most likely the block ground or the main fuse at the starter

 

[alldodge]

and there is spark.

The GL series motors use switches to apply a ground to turn ON the alarm, they have nothing to do with spark or fuel

Your motor uses a relay to energize the fuel pump. The pump is energized from power supplied by a Yel/Red wire coming from the key while cranking going thru a diode. The run side comes from the Alternator by a Green wire thru another diode.

Right now I don't see it being the diodes so start with the relay and it's connections

This is a GL-E

 

[Kwanza]

Thanks everyone. It looks like this time I might have a carburetor issue.
While previous shutoffs were all sudden and clean, no spluttering, the latest no-start had a little splutter and running for a second or two while key on start. Looking down my carburetor throat and advancing the priming manually, I could initially see a faint spray, but nothing now.
Is it possible to temporarily disable the default alarm on the ON position, just to try to listen to the fuel pump?

Thank you.

 

[Fun Times]

Disconnect the connector wire B in your photo as that should stop the horn....Or find the horn under/behind the helm/dash area and unhook a wire there...Or some will put tape over the horn speaker to get it toned down.

https://www.ebay.com/sch/i.html?_nkw=3817974&_sacat=0&_from=R40&_trksid=p2322090.m570.l1313

 

[Fun Times]

That carburetor appears very dirty and corroded possibly indicating water at some point got in there... Might be time for a carb tear down, inspection and rebuild.

 

[Kwanza]

Thank you.
That indeed stopped the alarm, and I can now listen when I turn key from OFF to ON. I can hear a single faint click from around the fuel pump every time I turn key to ON, no humming, no turning noise. I suppose I should hear a humming of the pump. If my engine has an electrical fuel pump as I assume and been told, and not a mechanical one, that is.

 

[Fun Times]

Thank you.
That indeed stopped the alarm, and I can now listen when I turn key from OFF to ON. I can hear a single faint click from around the fuel pump every time I turn key to ON, no humming, no turning noise. I suppose I should hear a humming of the pump. If my engine has an electrical fuel pump as I assume and been told, and not a mechanical one, that is.

You have a mechanical fuel pump... It's the one with the yellowish hose running to it / to the left of the white oil filter.
How about an overall view of the engine.

 

[Kwanza]

You have a mechanical fuel pump... It's the one with the yellowish hose running to it / to the left of the white oil filter.
How about an overall view of the engine.

Thank you. Another couple of images of the engine attached. Yes, that's the only place I have hose/tube coming from to the carburetor.
Since I have no fuel reaching the carburetor upon manual priming (with the throttle control or right on the carburetor), I'll have to investigate anti syphon valve, fuel pump, fuel lines. Fuel filter was changed few weeks ago by my mechanic, only did a single three quarter of hour trip since then.

I understand an electric fuel pump could potentially be shut down as a safety procedure by a struggling alternator or a faulty / overheating relay for example.
Would that apply to a mechanical pump as well, or if the pump is not working then it is bad. Assuming rest of fuel system (anti syphon valve, fuel lines) is ok?
Thank you.

 

[Fun Times]

No real safety features to it per se because if the engine isn't turning the pump is not being activated via the pumps arm inside the engine block.
Here's your pump, https://www.volvopenta.com/shop/0/part-sections/54168662?hintPhrase=&hintType=None

Carb, https://www.volvopenta.com/shop/0/part-sections/54142663?hintPhrase=&hintType=None

Though I believe there should be one more letter after your 3.0 GLP-?, that you should try to find to know for sure, here should be all your engine parts, https://www.volvopenta.com/shop/0/search?ft=3.0GLP

Maybe pull the fuel filter to see if there's still fuel in the area and no debris plus carefully see if you're getting fuel to the carb at the fuel inlet line that connects to the carb... You need to know if you're working forward towards/inside the carb or all the way back down to the fuel tank...

 

[Kwanza]

No real safety features to it per se because if the engine isn't turning the pump is not being activated via the pumps arm inside the engine block.
Here's your pump, https://www.volvopenta.com/shop/0/part-sections/54168662?hintPhrase=&hintType=None

Carb, https://www.volvopenta.com/shop/0/part-sections/54142663?hintPhrase=&hintType=None

Though I believe there should be one more letter after your 3.0 GLP-?, that you should try to find to know for sure, here should be all your engine parts, https://www.volvopenta.com/shop/0/search?ft=3.0GLP

Maybe pull the fuel filter to see if there's still fuel in the area and no debris plus carefully see if you're getting fuel to the carb at the fuel inlet line that connects to the carb... You need to know if you're working forward towards/inside the carb or all the way back down to the fuel tank...

Thank you, great help!
I'll start tomorrow by adding another 20 liters of fuel...gauge shows half, but who knows? Only got the boat a few months ago, and always kept fuel above the half mark, where it currently sits. The gauges are quite old, most of them behave, except the RPM that occasionally jumps without any throttle change, needing either a small knock on the front or a wiggle of the cables in the back to settle.
Then, onto the fuel line.
3.0 GLP-D, yes.

 

[Kwanza]

An update on diagnosing this above issue.

It certainly looks like the mechanical fuel pump.

1. Removed hose from pickup/anti-syphon valve from top of tank. Connected a clear hose, and checked for blockage here by slowly pumping/sucking up fuel. Fuel rises quite easily; there seems to be no blockage. Did not remove the elbow fitting itself for the rattle test, but there seems to be no anti-syphon valve in it I think, as fuel flows backwards as well. I understand this could be a safety issue (all my fuel lines are above the top of the tank), but it should not impede ignition.
2. Holding fingertip at end of hose from fuel pump, the suction seems way too weak, can barely feel the suction on my fingertip. I doubt it would hold a sheet of paper if attached. This could be deceiving though as a liquid filled line would likely have a better seal on one hand; and on the other hand, sucking up the fuel from the tank through the anti-syphon valve also seemed very easy, requiring a very small effort.
3. No fuel out of fuel pump when bottom end of stainless-steel fuel line disconnected at pump. (Pickup line at tank connected)
4. No fuel out of stainless-steel fuel line when disconnected at the carburetor (Pickup line at tank connected, fuel line at pump connected)
5. Both manual priming and engine turnover attempted.
6. Oil looks clear and does not smell of fuel.
7. No signs of any leaky hoses or leakage.

Another observation, as seen on bottom RHS of my last picture attached, both the fuel line from tank to filter and from filter to pump are connected to a port with an inward arrow, and the two ports with outward arrows are closed. This is how it was since I got the boat 6 months ago, having taken this photo before the fuel filter was changed. Does this really matter, and should these be repositioned?

Unless there is anything else I can check, I will be taking it to the mechanic to confirm the issue is the pump, and to replace it / repair it.

Thank you.

 

[alldodge]

As your state the filter is not done correctly. With it connected this way there is no filtering of the fuel and any crud is pump straight through to the carb

Does look like it needs a pump and the pump filter hose moved to the the other port, then clean the carb

 

[Kwanza]

The mystery deepens.
After 5 days of investigations (and no intended fix!) my fuel pump works and engine runs.
I've decided this morning to get a simple vacuum gauge and have some numbers on the vacuum this fuel pump creates, and not just a finger test, before I remove the pump and buy a new one.
Connected the vacuum gauge, and, not expecting much, I cranked the engine. 5....10....13 inch Hg.....in 5 seconds.
Connected hose back onto gas tank, with steel fuel line disconnected at pump.... cranked the engine.....lucky I wrapped a towel around it....squirting all over. Connected bottom of the steel fuel line to pump, and wrapped the towel around the top of the steel fuel line, just before the carburetor ....crank.....squirt. Connected it back to carburetor, did not start at first attempt with throttle control priming, might have needed one more push, primed it once more on the carburetor, noticed healthy squirting into the carburetor, then it started easily.

Since during last two months it cut off twice while on water, (once after ~5 km, second time after ~20 km), and last week just after retrieving the boat and would not start for a rinse down, I'll still have to figure out a fix. Maybe the incorrectly connected fuel filter ports mean I have some dirt in the pump, with some blockage, air lock, etc? I'll try a clean.

Thanks everyone for the help and tips, I'll be away from the boat for the next few weeks, I'll share the solution when I have one.
Thanks.

 

[Kwanza]

Time for humble pie.

I can see the experienced people starting to smile. ...

I've been deceived by a faulty fuel gauge/sender/float. That's for another day.

I ran out of fuel.

My gauge was on the half mark, with an empty tank. Would never go below half, I always thought I'm safe with half a tank of gas. I was on empty.
Added 20 liters a few days ago just to make sure, but this wasn't picked up the same day for whatever reason, airlock, etc. It was eventually picked up after removing all fuel lines etc. Added today the 2nd and 3rd 20 liter jerry can of fuel, gauge went up to 3/4. Tank capacity is apparently around 85 liters. Then added the 4th 20 liter jerry can, showing full now. And could probably take a bit more.
Lucky, I didn't pull my fuel pump off.

Did a 60 km trip early in the year after topping up the tank.
Some small spins around the harbour after that.
In April, went out with a friend, (gauge at half mark), stalled after 15 minutes. I was blaming the alternator and the bilge blower as playing up and shutting down my fuel pump (at the time I assumed I had an electronic fuel pump, not mechanical).
Added 20 liters of gas, (on top of half mark gauge, just to be sure).
Went out for a drive, and I stalled after approximately one hour, ~33 km. That's how much the 20 liters of gas lasted...I was on empty again, blaming fuel pump.....again.
Another 10 liters added, this was chewed up by test ride after servicing and my last 15 km trip last week, when I got to port with literally the last drops, as it cut out when I hooked up the garden hose for a rinse.

First time since having this boat (~6 months), I added 80 liters of gas, and not pitiful 20 liter amounts.
Thanks everyone, and be safe.

 

[Fun Times]

Reminds me that I just saw something similar just today... I was getting a new windshield installed, a 70's looking gentlemen pulls in with an older, squeaking suspension full size 1980's van and says the windshield fluid won't spray after you put a new windshield in not long ago and he (the van owner) says I checked everything, windshield owner starts looking at hoses saying I don't think we touched the water lines and nothing seems disconnected, then store owner says where is the water fluid reservoir? van owner says right there, store owner says did you check it for fluid? van owner, no, store owner, it looks empty, I'll add water to test, it now sprays, van owner embarrassed, what do i owe you? store owner big smile 10K, van owner store owner, happy to help and thanks for being a customer, we'll take care of your other car soon too, a Honda accord.