Question regarding 1999 Volvo Penta 5.0GL and power to the fuel pump relay

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Garutlan

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Greetings! First post even though I signed up in 2023.
I have a couple of questions:
1. Have a '99 Volvo Penta 5.0GL with I believe a fuel delivery issue; when searching the forum I see the 4.3GL threads....do the two engines use the same fuel systesms (i.e. if I read the 4.3GL posts - is it applicable to me on the component level??)
2. When should the fuel relay be energized, when the ignition is turned "on" (Should it engage to prime the pump? When I turn my switch to "on" the relay does not engage the contact. When I remove the relay and check the voltage I get 2 volts across the wires when the key is "on". I am trying to understand when the relay should engage. (consequently - I did jump the pump at it does run).
3. Lastly. I am struggling to find a schematic for the 1999 Volvo Penta 5.0GL fuel delivery system or really a good overall manual. I see on ebay, online, etc... and am willing to pay but not sure exactly what is worth the money- any advice appreciated.
 
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Garutlan

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alldodge said:
Welcome
Which GL do you have , GL-B, GL-C......?
Click to expand...
Not sure exactly the sticker on the inside where the wiring harness plug mates together says 5.0 GL PWTR. Where would I look for the "B" or "C" designation?? Thanks-Geoff
 
alldodge

alldodge

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Garutlan said:
Not sure exactly the sticker on the inside where the wiring harness plug mates together says 5.0 GL PWTR. Where would I look for the "B" or "C" designation?? Thanks-Geoff
Click to expand...
Looks like the PWTR was made before the GL-A and the attached is the A model. Should be close to what you have
VP wiring GL GS 5.jpg
 
ESGWheel

ESGWheel

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Here is a close-up of the pump relay socket wiring. In following the wiring diagram that AD posted it appears the fuel pump does not kick on with “Key On”. It only gets power with “Key to Start” and once the motor is running, from the Alternator. Here is how:
  • Notice the OR wire labelled “from start relay” > if you follow that back to the starter relay you will see that it turns into a Y/R wire and is the same wire that applies voltage to the starter solenoid when the key is turned to start. Once the engine is running and key back to run, the power comes from that GN wire that goes to the alternator. Notice there are diodes (one way electrical valves) on both of these wires to preclude back feeding.
Since this is a carb’ed engine the logic is there is a float bowl full of fuel and thus no need to ‘prime’ the fuel system like on an injected engine. Others may know better and there is a logic to priming even a carb’ed engine since it’s a boat and could be sitting for a long time, allowing the float bowl fuel to evaporate.

Why do you think you have a fuel delivery problem? Is it b/c the pump does not run when the engine is running, and it runs out of fuel? If the pump runs with the relay jumped, then this is an electrical issue. Also, what pins did you see the 2VDC accross?
  • Please explain in more detail your issue and what you have done to troubleshoot.
Pump Relay.png
 
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Garutlan

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Thanks for all the information from the forum. Some good diagrams and information- I really appreciate your willingness to help me.
Admittedly, the Labor Day weekend took me away from any boat work. I am hopeful to get back on it this week.

Background: the boat- has been sitting for a season and a half as I was working on trim cylinders, hoses, etc. I got all that back together and was looking to crank her up. She did run prior to the trim cylinder issue (a season and a half ago). Engine would turn over but never start. I sprayed a little starter fluid in the carburetor and she would turn on briefly. Made me wonder about fuel issues- maybe bad fuel, maybe clogged filter, etc. YouTube kept mentioning an audible click when in the “on” position. Never heard that- silence when I would turn the key.
The other thing that led me down that path is that when I checked the fuel filter and emptied it- it never filled back up with fuel (filter). When I would turn it “on”. My thinking was that it would prime to fill the fuel line. Which led me to looking for details around the fuel pump. Limited schematics, etc. so I started with the relay that engages the fuel pump. Never got any voltage with the ignition switch “on”.

Which led me here-
I will confirm that I get voltage when I try and “start” the engine.

Thanks again for the schematics and descriptions. I do appreciate it and will follow up with findings.
 
alldodge

alldodge

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You only see voltage on pin 85 (86 Gnd) when the motor is cranking. There is no voltage present with key being turned to ON

If there is no voltage on 85 when cranking then find the diode (item 12, post 6) and see if it is open.
 
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Garutlan

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alldodge said:
You only see voltage on pin 85 (86 Gnd) when the motor is cranking. There is no voltage present with key being turned to ON

If there is no voltage on 85 when cranking then find the diode (item 12, post 6) and see if it is open.
Click to expand...
When in the “On” position I get 2 volts across 85 and 86. I did not try to actively “Start” the engine with meter attached, but based on what you showed from the schematic- I would suspect I am getting voltage there and it might not be the relay or the pump. Will let you know. Thanks-
 
kd4pbs

kd4pbs

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Measure the socket at pin 30 and 87 - there should be battery voltage on one of them when the key is on. This is the supply side of the relay. The other pin (that does not have battery voltage) will go the the + side of the fuel pump. Try using a jumper wire between pin 30 and 87 of the socket, and it should activate the fuel pump. The key may need to be on - I'm not sure how VP set this one up.
Update: I see there was a diagram posted. Key won't need to be on. Battery voltage should be found on pin 30.
 
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Garutlan

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Yes
kd4pbs said:
Measure the socket at pin 30 and 87 - there should be battery voltage on one of them when the key is on. This is the supply side of the relay. The other pin (that does not have battery voltage) will go the the + side of the fuel pump. Try using a jumper wire between pin 30 and 87 of the socket, and it should activate the fuel pump. The key may need to be on - I'm not sure how VP set this one up.
Update: I see there was a diagram posted. Key won't need to be on. Battery voltage should be found on pin 30.
Click to expand...
I have confirmed in the past that I do have voltage on pin 30 at all times with the battery connected. I was thinking that I was not getting power with ignition in “On”through 85 and 86 to engage the relay passing power through to the pump, but I am believing based on what the schematic and discussion is saying that I will not get voltage and engage the relay until I actually turn the ignition to “Start”. I will check that and report back. Thanks-
 
ESGWheel

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Thanks for the additional info. Frankly I think you are chasing in the wrong direction. Follow the logic here:
  • Ran before a season and half ago, no issues. Been sitting since with no work on the engine systems.
  • Tried starting and would crank but not start.
  • Used some starter fluid and it fired off but did not run (so getting spark and an indication of ok compression and all other major mechanical)
  • You were expecting the fuel pump to run (i.e. prime) with the Key On and did not hear the ‘click’ nor did you see the voltage expected, BUT when relay jumped the pump ran. Hence the thinking is that some issue with getting the pump to run. But in fact, pump does not run with key On (and motor not running).
  • Yet even after you jumped the relay and ran the pump, motor still did not start (I get that you may not have the relay jumped and tried to start, but having the pump run should have filled the carb float bowl with gas).
To me that means potentially bad fuel, or something clogged up in the system and / or carb.
Here is why: this is a carb’ed engine and after sitting for 1.5 years, the fuel in the carb evaporated. With all the cranking you did (and jumping out the relay), it should have filled the carb float bowl and all would be right as rain but it was not.
Here are my suggestions and in order:
  1. Remove the spark arrestor and with key off, use a flashlight to look down the carb throat and have someone advance the throttle fully open in a smooth stroke. You should see the accelerator pump squirt a nice steady stream of gas (akin to a syringe squirting out when depressed). (I suspect no squirt).
  2. Turn on the battery and jump the fuel pump relay as before. Let it run for 30 or 45 seconds. Remove jumper and repeat no. 1 above.
  3. If squirt, jump out the relay again (so fuel pump running) and try to start.
    1. If runs, Yea! And let it warm up checking temps and pressure, etc. Then shut down.
    2. Remove jumper, install relay and try to start again and if all good, enjoy boating.
    3. If does not run probably bad gas.
  4. If no squirt, further troubleshooting begins.
Please post results of each step and any questions. Your issue is 100% solvable and you will get there with the help of this excellent forum, so hang in there!
 
Last edited:
kd4pbs

kd4pbs

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Yes, you will not get the pump running until you turn the key to start. Once started, the voltage from the alternator will sustain that relay coil while the engine is running. There are diodes in both the orange lead from the start relay and the alternator which prevent any power back feeding and hanging the starter on or damaging the alternator.
If you jumper 30 and 87, you can at least verify that the pump is working, which would narrow things down to either the relay, the relay socket, or the diode in the starter lead.
 
kd4pbs

kd4pbs

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My younger self would never have imagined the reality. I guess those of us who go through it should feel blessed somehow. LOL
 
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Garutlan

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Ok. I was able to do some troubleshooting last night. Tried to follow the scenario from ESGwheel above with a few tweaks to confirm fuel through the pump from the tank.

1. I did jump the pump and pumped fuel from tank into the filter.
2. Removed fuel hose on top of pump and verified fuel discharge through the pump.
So that is good.
3. Next verified that there was not a restriction in the fuel hose from the pump to the carburetor. Took it loose on both ends and “passed gas”😜 through it.
4. Hooked hose back up and ran pump again- which should fill the line to the carburetor, correct.
5. Removed flame arrestor and did not see a steady stream of gas or any fuel when the throttle was being manipulated (forward or reverse).
6. I will try the process again- and confirm-

Just wanted to update with feedback, since y’all are nice enough to help me out. Really appreciate it!👍🏼
 
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