fuel pump not pumping

superninja2

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May 10, 2012
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Hello. I have a 1998 Volvo Penta 4.3 GL (6 cylinder). When the boat was not starting I thought it might have been because of water condensation over the winter. I changed the oil, oil filter, fuel filter, and spark plugs. After all of this it was still not starting so I checked that I was getting spark and I was. I there was zero gas going to the plugs. Then I pulled out the fuel hose and put one end into a bucket, tried starting again but I did not see any gas. Ok. Fuel pump is out. I was going to change out the fuel pump and noticed that it was right above the fuel filter and not in the actual tank(working without an owners manual). Looks like there is a couple of relays(one is a Potter Brumfield relay) around the fuel filter. Could the relay be out? Is there also an alternator relay that sends current to the fuel pump relay in order for the fuel pump to get activated? At this point I may just bring it in to the shop, but if it is easy to switch out the relay I may just do that? Kind of strange this when I brought the boat in last season everything was working fine? Thanks
 

Doc_V

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May 14, 2012
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Re: fuel pump not pumping

Don,

I'm a friend of the OP trying to help out since I know a bit more about engines. I've worked on many different types over the years, but this is my first boat motor, which means I know just enough to be dangerous. I know that a lot of the basics don't apply to boats because of the water corrosion and contamination issues, so It's best to assume we know none of the essentials specific to boats.

As the OP mentioned, we've been flying blind since we don't even have an owners manual, though he found one online today and I plan to read through it. If you know of a free online version of the service manual, that would be a massive help.

What we do know at this point is the boat was working fine last season. It sat over the winter and I believe he forgot to fill the tank or add any fuel stabilizer. When he tried starting it recently, it turned over but wouldn't start, so he's done the work mentioned in the first post.

I read the post you referenced for testing the relay, but to be perfectly honest, we don't even know if that's the problem. Before we start tearing into anything else, can you give us some basic troubleshooting steps to take, as well as any warnings about what not to do?

Thanks and much appreciation!
 

Don S

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Re: fuel pump not pumping

Did you look at the link I posted in my previous reply? Obviously not, because that was how you test the system, not the relay.
 

Doc_V

Cadet
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Re: fuel pump not pumping

OK, so we tried the jumper test and got power to the pump. At first when connected the power to the pump, it'd just click. I did this several times thinking the pump might be gummed up, in hopes to break it loose and salvage the pump. Sure enough, it worked. and eventually, the pump started working, but only briefly. I disconnected the fuel line to the carb to see how much it was pumping and this seemed to help as it was began flowing better out the top. I reconnected the fuel line and we started the motor. Success! ... Or so we thought. They're was a grinding sound coming down low from the starboard side, so we shut the motor off. It sounded as if the starter was not disengaging. We had been having issues with the key tumbler and figured it might be the problem, then the boat started acting strange, as it would start, but not stay running.

We replaced the ignition switch but still the same. The boat starts, but will not run.

I tried pouring some gas directly in the carb to see if it would make a difference and it helped, but it then dies as soon as it burned up that fuel.

So we're kind of stumped at this point. Any ideas?
 

Don S

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Re: fuel pump not pumping

In thedrawing below, make a jumper cable with 2 male spade terminals that will fit the socket relay. Get ready to start the engine (water, muffs, etc.) Remove the fuel pump relay and Jumper across the 87 (yellow/red wire) and the 30 (red/purple wire) terminals. The pump should be running. Now, start the engine and with a DVM, check the voltage on the green wire terminal on the alternator. What is the voltsge. Then, check the 85 (green wire) terminal on the relay socket. What is it's voltage?

Now shut the engine off and remove the jumper from the relay socket to stop the fuel pump.


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Doc_V

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Messages
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Re: fuel pump not pumping

In thedrawing below, make a jumper cable with 2 male spade terminals that will fit the socket relay. Get ready to start the engine (water, muffs, etc.) Remove the fuel pump relay and Jumper across the 87 (yellow/red wire) and the 30 (red/purple wire) terminals. The pump should be running. Now, start the engine and with a DVM, check the voltage on the green wire terminal on the alternator. What is the voltsge. Then, check the 85 (green wire) terminal on the relay socket. What is it's voltage?

Now shut the engine off and remove the jumper from the relay socket to stop the fuel pump.

Thanks for the quick reply, but not seeing the drawing on this end.
 

Don S

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Re: fuel pump not pumping

That's because I forgot to put it in :facepalm:
 

Doc_V

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Re: fuel pump not pumping

Tested the lines and got 1.65 to 1.67 at the alternator and .02 at the relay. So where does that leave us?
 

Don S

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Re: fuel pump not pumping

Sounds like you need to get the alternator repaired or replaced.
 

Doc_V

Cadet
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Re: fuel pump not pumping

Thanks for the help but now I'm getting really confused. What could have caused all this?

They seem like unrelated issues, i.e.:
- Gummed fuel-pump
- Starter wont disengage
- Motor starts but won't run.
- And now bad alternator?
 

Doc_V

Cadet
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Messages
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Re: fuel pump not pumping

Thanks for the help but now I'm getting really confused. What could have caused all this?

They seem like unrelated issues, i.e.:
- Gummed fuel-pump
- Starter wont disengage
- Motor starts but won't run.
- And now bad alternator?

Bump....

Don,

I appreciate all your help, but this is not my boat, I'm just trying to help out a friend and at this point, I'm not feeling too comfortable about chasing all sorts of seemingly unrelated issues, and costing the owner lots of money, without knowing why. All I'm asking for is a little clarification here. Please help me understand how they're related and what could have caused everything.

Thank you.

...If anyone else reading this can offer some assistance, I sure would be grateful for any help.
 

Don S

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Re: fuel pump not pumping

They may not be related by anything. The fuel pump won't keep running because the alternator doesn't work. The starter is probably not related to that at all. The fuel pump being gummed up means it probably sat for a long time. I don't know the history of the boat or engine, nor can I see it so can't say how it all relates.
 

Doc_V

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Messages
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Re: fuel pump not pumping

There's no doubt the fuel pump was gummed up from sitting without stabilizer, we all agree on that one. However, based on your suggestion of creating a jumper between terminal #87 and #30, I was able to eventually break the pump free and get it working again. At that point, the motor *did* start and run; though it sounded like the starter would not disengage. It wasn't until a few minutes later that it would only start, but then die whenever the key was released from the start to run position. That's what's confusing me, what could have happened in those few minutes to cause this? Is there something we could have done that caused the alternator to fail? If so, I'd sure feel better knowing what it is, so we don't repeat it again.

Also, doesn't using the jumper between 87 & 30 provide constant power to the pump? In which case, shouldn't the fuel pump continue to run regardless of the alternator and therefore the motor should continue to run?
 

Don S

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Re: fuel pump not pumping

Also, doesn't using the jumper between 87 & 30 provide constant power to the pump? In which case, shouldn't the fuel pump continue to run regardless of the alternator and therefore the motor should continue to run?

With that jumper, the pump should run, even with the ignition key off. It will run any time the battery is hooked up to the engine.
 

Doc_V

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Messages
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Re: fuel pump not pumping

With that jumper, the pump should run, even with the ignition key off. It will run any time the battery is hooked up to the engine.

If that's the case, then [using the jumper] shouldn't the motor run regardless of whether or not the alternator is functioning properly?
 

Don S

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Re: fuel pump not pumping

Yes. with the jumper hooked up, it's like running a wire straight from the batteries positive terminal to the pump.

Are you saying the pump is working for a while then stopping?

Tested the lines and got 1.65 to 1.67 at the alternator and .02 at the relay.

Exactly how did you test and get those numbers? Where did you have the test leads of your meter?
 

Doc_V

Cadet
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Messages
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Re: fuel pump not pumping

Yes. with the jumper hooked up, it's like running a wire straight from the batteries positive terminal to the pump.

Are you saying the pump is working for a while then stopping?

Exactly how did you test and get those numbers? Where did you have the test leads of your meter?

The fuel pump is not stopping. Once we got it unstuck, it works as long as the jumpers are plugged in, which is why it's odd that the motor starts but will not stay running.

It would seem it's either an ignition issue or perhaps the carb.

I'm not familiar with this carb, but if it has a separate starter and main jet, it would make sense that whatever was gumming up the fuel pump, broke loose and clogged up the main jet. That would explain why the motor ran for a few mins when we first got the pump running again; and now it starts but wont stay running.

What are your thoughts that?

As far as testing the alternator, after placing the jumper between terminals 87 & 30 on the relay socket, I had to scrape some paint off the bolt holding the green wire on the back of the alternator and touched it with one lead of the VM, then grounded the other VM lead, while someone turned the motor over.

Then I did the same by plugging the VM lead into socket #85 [with the jumper still in place] and grounding the other lead while someone turned the motor over.
 
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