Volvo 4.3 Fuel Issues - another one

[rjd75]

Ok, thought I would start my own thread as I am experiencing this problem much more frequently now. What used to happen once a season has now happened 3 weekends in a row. I need some advice in what order to attack this.. Can't be going out with my 3 & 5 year old and bobbing around while dad jumps the relay and messes with the fuel filter.

So since I bought it 10 years ago my boat has periodically had a fuel starvation issue here is what I know.

- It always happens during take off
- a few of the times it has happened I was playing with the trim while planing
- Boat is usually warmed up and whether is warm and humid
- Fuel tank level does not matter has happened on full tank
- anti siphon was replaced
- fuel pickup checked for cracks
- fuel pump relay swapped
- fuel filter swapped many times

What happens is the fuel filter has some of the fuel missing out of it once it dies. Jumping the relay socket often times sucks up the fuel out of the tank and you can hear the pump change tone when it starts sucking gas. Put relay back in fire up and away you go. Other times I have to top up the fuel filter in order to get the pump to suck gas again.

This last time I was adjusting the trim before hitting the throttle and noticed the voltage dropping to 12 or less on the volt meter. When I took off it sputtered and died. That time I was able to jump the relay suck up gas and go without messing with the filter. When I came back I trimmed up the motor and the trim did not affect the voltage any more than a jolt of the needle, so not sure whether this is an indication that the alternator is bad. Don S recommended check connections for air leaks, will do this this weekend, but if that does not solve it what should I do next? Diodes? Alternator? Fuel Pump? What do you test for on the alternator to see if there is a problem? There is a local alternator shop that I am thinking of taking it to, but want to be able to describe the issue to the guy. I am pretty much just going to replace all parts involved until I solve this as it is really annoying. It always ends up running just with great uncertainty as to when it will happen next, and only on take off, never ever has it happen any other time, definitely not while under way. I know that if I pass the initial take off I am good for the trip until I shut off and start again, then I roll the dice!

 

[rjd75]

Re: Volvo 4.3 Fuel Issues - another one

Has anyone ever replaced the diode? Trying to locate the part number and having difficulty.. Assuming they are the same part across all 4.3GLs? If not a part number just a spec for what I need to buy from an electronics supplier, eg. would one of these standard 1N5822T diodes do the job? Thanks.

 

[2rfc2]

Re: Volvo 4.3 Fuel Issues - another one

When you say anti- siphone do you mean the check valve between the fuel tankand the fuel filter?

Ok, thought I would start my own thread as I am experiencing this problem much more frequently now. What used to happen once a season has now happened 3 weekends in a row. I need some advice in what order to attack this.. Can't be going out with my 3 & 5 year old and bobbing around while dad jumps the relay and messes with the fuel filter.

So since I bought it 10 years ago my boat has periodically had a fuel starvation issue here is what I know.

- It always happens during take off
- a few of the times it has happened I was playing with the trim while planing
- Boat is usually warmed up and whether is warm and humid
- Fuel tank level does not matter has happened on full tank
- anti siphon was replaced
- fuel pickup checked for cracks
- fuel pump relay swapped
- fuel filter swapped many times

What happens is the fuel filter has some of the fuel missing out of it once it dies. Jumping the relay socket often times sucks up the fuel out of the tank and you can hear the pump change tone when it starts sucking gas. Put relay back in fire up and away you go. Other times I have to top up the fuel filter in order to get the pump to suck gas again.

This last time I was adjusting the trim before hitting the throttle and noticed the voltage dropping to 12 or less on the volt meter. When I took off it sputtered and died. That time I was able to jump the relay suck up gas and go without messing with the filter. When I came back I trimmed up the motor and the trim did not affect the voltage any more than a jolt of the needle, so not sure whether this is an indication that the alternator is bad. Don S recommended check connections for air leaks, will do this this weekend, but if that does not solve it what should I do next? Diodes? Alternator? Fuel Pump? What do you test for on the alternator to see if there is a problem? There is a local alternator shop that I am thinking of taking it to, but want to be able to describe the issue to the guy. I am pretty much just going to replace all parts involved until I solve this as it is really annoying. It always ends up running just with great uncertainty as to when it will happen next, and only on take off, never ever has it happen any other time, definitely not while under way. I know that if I pass the initial take off I am good for the trip until I shut off and start again, then I roll the dice!

 

[rjd75]

Re: Volvo 4.3 Fuel Issues - another one

Yes, mine is threaded into another fitting that is threaded in to the tank. It then has a barbed connection where the fuel line connects and goes up to the pump and filter. One other thing I should mention is that I have one of those perko hidden fuel vents that's underneath the cap. At one point I was suspecting that the tank could not vent itself properly and therefore the pump could not suck gas, however when this happens I always unscrew the fuel cap and it comes undone with ease, no suction at all.

 

[rjd75]

Re: Volvo 4.3 Fuel Issues - another one

Ok, finally got to the boat for some tests.. First off here are my numbers to conform to forum rules..

4.3GL PEFS
4110199022
3869053

So here is what I did.. Started the boat and checked voltages at alternator terminal, relay socket and fuel pump connection. There is no corrosion anywhere and everything read a solid 14V, the alternator, the relay contact that connects to the green wire and diode and ignition and diode (with engine running and fuel pump jumpered) and finally the fuel pump connector, which I pulled and measured while the engine was running. The wire on my alternator is more yellow than green not sure if it's faded. Here is a pic..

Next I spliced in about 5 inches of clear vinyl tubing just before the fuel line attached to the fuel filter. What I saw here was interesting.

Test #1 Jumpered fuel pump and started engine

I slowly watched the fuel climb up the clear tubing, it took a good few seconds for it to fill that little area of tube no bubbles just fuel. I then started the boat and looked for air bubbles. There was pretty much no bubbles in there, one microcopic bubble every few seconds. I then pulled the jumper to shut the fuel pump so I could watch the fuel stop flowing in the clear line. When I did this I experienced pretty much the same thing that happens to me on the water, you could tell by the sound the motor was running out of fuel because the pump wasnt pumping. I unscrewed the filter and it was missing some fuel.

Test #2 Filter filled back up and fuel pump jumpered

This was interesting, the fuel pump jumpered alone could not suck gas up the clear fuel line, it was clearly struggling. I let it run for a while and it just kept pumping but no fuel, infact the fuel started dropping in the clear tube which I thought was odd because I thought the antisiphon should prevent that. I then started the engine and still nothing, I bumped the throttle a few rpms and finally fuel start to flow.

Test #3 Fuel pump Jumpered, confirmed filter was full

This time I decided to take a video so that everyone could see what is happening, I wished I had taken one the first time so you could see the difference. In test #1 when I first spliced in the clear tube it slowly but surely filled the clear tube on jumper alone, no engine runnning. This time after letting the fuel drop out of sight of the clear tube I jumpered it and it shot right up for part of the tube and then struggled to get to the top. It's difficult to see but it never really starts pumping fuel. You will also see when I pulled the jumper and the fuel starts dropping in the tube. Is this normal for an anti siphon to allow fuel to drop down the fuel line at this rate? Anyways, at this point I am thinking of just replacing the fuel pump, it seems to be very inconsistent.

http://www.youtube.com/watch?v=xPJqjLRa00o

 

[jerryjerry05]

Re: Volvo 4.3 Fuel Issues - another one

With no obstructions how much does the pump produce?
Unhook all the lines and pump it into a can/jug.
Get a fuel pump pressure tester.Should be I think between 5-7#(I think) get the specs.
That stuff in the line looked like water.
Just because the pump sounds like it's working it might not be good.J

 

[Don S]

Re: Volvo 4.3 Fuel Issues - another one

You MUST do these tests, the results will tell you what to look for.
http://forums.iboats.com/showthread.php?t=167561

Don't just take things apart and look at them, or replace them, DO THE TESTS and report your gauge readings and clear hose findings.

 

[rjd75]

Re: Volvo 4.3 Fuel Issues - another one

Just came back from the vacuum test.. put vacuum in line before filter, jumped relay no engine power at this point.. pump running just off battery. Registered 1Hg on the guage and no fuel coming up the clear tubing.

Started the engine and reved it up a few rpms, guage move up to about 2Hg and fuel started coming up the line. Took it out for a drive and drove it right up to 4600 rpm, guage never registered more then 2.5hg smack in the middle between 0 and 5. No air bubbles in the line, at least nothing worth mentioning.

Next I pinched the fuel supply with some pliers after 10sec it was still reading 2Hg with the engine running, I let go and took a good while to start gas flowing up the tube. Pinched again and after about 40-45 seconds it finally crept up to just over 5 maybe 6Hg. Motor does sound a bit different then I remember, like its starved for fuel but could just be my imagination.

Also nobody answered the question about the anti-siphon/check valve on the gas tank. Should this be a tight seal because when ever I shut down the gas in the line slowly seeps back in to the tank. The anti siphon was already replace, but can replace again I guess. Normally they are stuck closed not stuck open???

 

[rjd75]

Re: Volvo 4.3 Fuel Issues - another one

Ok no replies since my other post.. But here is what I have done and the mind boggling problem I have..

New Fuel Pump
New O rings
New Fuel Filter
New Anti Siphon Valve
Pipe doped all connections

Tested vacuum.. Not much difference runs at 2 WOT now vs 2.5 not sure if that's better or worse. The more interesting thing is this damn antisiphon valve which I am guessing is the real root of the problem. After replacing it, it STILL pours all of the gas out of the fuel line back in to the tank!! So I figured maybe it is because it is mounted horizontally and tilts back a littel when the boat is in the water. I testedthe old one by attaching a piece of fuel line and pouring some gas down it and it shut tight and did not lose a drop. So I put a 90 elbow on the fitting on the tank so that the anti siphon is now sitting vertical, figured this must cure the problem now.. I couldn't believe my eyes.. Shut down and gas went straight back down again. What the hell is going on here? At this point there must be some negative pressure in the tank or something causing the valve to stay open and let gas down??? Ready to just install an inline primer bulb and call it a day. So much time and money wasted on this..

 

[Don S]

Re: Volvo 4.3 Fuel Issues - another one

Damnit .......... typed up a reply and it's not here . Grrrrrrrrrrrrrrrrrrrrrrr

 

[Don S]

Re: Volvo 4.3 Fuel Issues - another one

Have you pulled the pickup tube out of the tank and checked the screen on the end of it to see if it's plugged up?

Do you actually have a running problem, or just the filter not staying full?

 

[rjd75]

Re: Volvo 4.3 Fuel Issues - another one

Screen on pickup and screen on carb end are clean as a whistle.. Just pulled them last night.. Motor runs 100% just occasionaly dies on take off and I usually find the fuel filter half empty. This may go away now with the new pump but I am wondering if this siphoning issue is what causes the pump problems. HOWEVER, I did some reading on anti siphons and apparently they are supposed to prevent siphoning OUT of the tank in the event that you have a ruptured line you don't want to fill you bilge with fuel. So is it normal for the fuel to flow back in to the tank? Some info I found said that this was normal and that it is designed to prevent siphoning but a fuel pump has enough stength to pull fuel past it. I just want to rule out the fuel flowing down the tube as a cause for pump failure or the root of the problem.

 

[Don S]

Re: Volvo 4.3 Fuel Issues - another one

Too lean an idle mixture adjustment on the carb, or a week accelerator pump will do that. You're probably chasing ghosts with the half filled filter.

 

[mark Johns]

Re: Volvo 4.3 Fuel Issues - another one

Did you ever get to the bottom of this. I have same similar issues happening. Pump runs when jumped, got new relay, anti siphon which does leak back, and tough start up and sometime dies on take off.
Mj from Montana

 

[2rfc2]

Re: Volvo 4.3 Fuel Issues - another one

the anti- siphon /check valve cannot leak.... The pump will time out if it does'nt get filled or your pump relay is bad.

 

[Don S]

Re: Volvo 4.3 Fuel Issues - another one

the anti- siphon /check valve cannot leak.... The pump will time out if it does'nt get filled or your pump relay is bad.

Sorry, but you are wrong on all three counts.

antisiphon valves can and do leak, the pumps do NOT have a timer circuit, and his pump is running, so the relay is working.

 

[2rfc2]

Re: Volvo 4.3 Fuel Issues - another one.

Re: Volvo 4.3 Fuel Issues - another one.

the anti- siphon /check valve cannot leak.... The pump will time out if it does'nt get filled or your pump relay is bad.[/Q$UOTE] So your saying the relay will stay closed for an unlimited time until the thing burns up or the pump burns up. I don't think thats the case.

 

[Don S]

Re: Volvo 4.3 Fuel Issues - another one.

Re: Volvo 4.3 Fuel Issues - another one.

So your saying the relay will stay closed for an unlimited time until the thing burns up or the pump burns up.

The pump will continue to run as long as the engine is running. The relay gets power from the alternator. Of course if the carb runs out of fuel and the engine stops running, the alternator will stop activating the relay.
The point is, it is not a timer of any kind.
You stated "The pump will time out if it does'nt get filled or your pump relay is bad." and that my friend is false.
There is no timer in the pump, and if the relay stuck closed and there was no fuel to the pump it would burn up.

 

[cobalt252]

Re: Volvo 4.3 Fuel Issues - another one

What does this anti siphon valve look like? Where can I buy a brass anti siphon valve (p/n, vendor etc.)?

Throubleshooting fuel problems on my 7.4GI Volvo Penta.

 

[bruceb58]

Re: Volvo 4.3 Fuel Issues - another one

What does this anti siphon valve look like? Where can I buy a brass anti siphon valve (p/n, vendor etc.)?

Throubleshooting fuel problems on my 7.4GI Volvo Penta.

You should start your own thread with your problem. You will get better responses that way.

First thing I would do to get the fuel tank and related hardware out of the picture is to run on a portable tank first.