4.3GL VP Fuel Pump Issues

[BBBux25]

Hi gang, I could really use some help here, thanks in advance.
2001 Glastron 185GX 4.3GL Volvo Penta Engine. I have a crank, no start condition. I did recently replace the starter. I've determined that the carb is not getting fuel when cranking from the fuel pump when the cranking. If I pour gas in the carb it will run for 1-2 seconds, then die. With the fuel line disconnected at the carb nothing comes out, but it does come out if I put 12v direct.

As far as further diagnostics here's what I've determined/done:

• Put 12v to fuel pump directly from battery, and determined it runs and pumps gas steadily to carb line (from both tank or seperate gas can) Which should in theory eliminate anti-siphon valve and confirms that the fuel pump at least works moderately well.
• Tested relay by putting 12v and ground to 85 + 86 and I get a click. Not sure if this is really a conclusive test to the internals of the relay, so I think I should replace it anyway.
• Confirmed I get 12v on terminal 30 of the fuel pump relay wire harness.
• Confirmed I get 12v at the fuel pump wire connector downstream of the relay when I am cranking the ignition.
• Confirmed continuity of the ground wire at the fuel pump relay wire harness.
• I tested the diodes both the alternator to fuel pump circuit (green) and starter to fuel pump harness (red/yellow) wire. I got ~500mA going one way and OL going the other way, which I believe means both diodes and connections are okay, but I don't mess with diodes ever.
• I tried using a single jumper wire from terminal 87 (fuel pump wire) to terminal 30 (always on 12v wire), nothing happened which was interesting because I thought that would turn on the fuel pump. I'd like to try this again to make sure I'm not going crazy, unless I am missing something. The terminal had continuity to the fuel pump connector end, both the ground wire on the fuel pump connector and the fuel pump harness show continuity to battery ground as well.
• Fuel pump 7.5amp fuse is good and I've also swapped spare fuse(s) with no luck. 40 amp fuse is good as well.

I'm banging my head against the wall at this point, as I've fixed a bunch of issues on the boat and now this pops up when I try to get it started, it's been sitting for 2 years. Appreciate any help at all!!!

 

[ESGWheel]

First off, nice posting. Detailed and you are following a logical progression in your troubleshooting.

To make sure I am fully understanding I am going to repeat in my own words what I think is a summary:

• You apply 12V to pump with a jumper and it runs with a confirmation of outputting gas since had the fuel line disconnected at the carb.
• You get 12V at pump when cranking but engine does not start
• You can pour a little gas into carb and it will run for a few seconds.

Is above, correct?
If so here is where I need some help understanding more: under what conditions does this happen: “With the fuel line disconnected at the carb nothing comes out, but it does….”

• Do you mean nothing comes out when fuel line disconnected, and you are cranking the engine?

Recommend trying this test: with all hooked up as usual jumper the pump to get the pump running for 30 sec or so (to ensure carb float bowl is filled) and then try to start the engine (with jumper still connected).

• What happens?

 

[alldodge]

Welcome
Great testing procedures

Put 12v to fuel pump directly from battery, and determined it runs and pumps gas steadily to carb line

• Confirmed I get 12v on terminal 30 of the fuel pump relay wire harness.
• Confirmed I get 12v at the fuel pump wire connector downstream of the relay when I am cranking the ignition.
• Confirmed continuity of the ground wire at the fuel pump relay wire harness.

12V on 30 and 12V at/on fuel pump wire when cranking

I think the issue is with ground or your testing method is in error. There is 12V while cranking but pump does not run.

 

[BBBux25]

First off, nice posting. Detailed and you are following a logical progression in your troubleshooting.

To make sure I am fully understanding I am going to repeat in my own words what I think is a summary:

• You apply 12V to pump with a jumper and it runs with a confirmation of outputting gas since had the fuel line disconnected at the carb.
• You get 12V at pump when cranking but engine does not start
• You can pour a little gas into carb and it will run for a few seconds.

Is above, correct?
If so here is where I need some help understanding more: under what conditions does this happen: “With the fuel line disconnected at the carb nothing comes out, but it does….”

• Do you mean nothing comes out when fuel line disconnected, and you are cranking the engine?

Recommend trying this test: with all hooked up as usual jumper the pump to get the pump running for 30 sec or so (to ensure carb float bowl is filled) and then try to start the engine (with jumper still connected).

• What happens?

Thanks for your reply. The above is correct! With the fuel line disconnected from the carb and all other electrical connections are plugged in, when I crank over the engine no fuel comes out of the fuel line, it just turns over, no fuel comes out. If I directly jump the fuel pump w/ 12v from the battery, fuel DOES come out.

I will try to jump it like you described and fill the bowl and see what happens, that is a good idea.

 

[BBBux25]

Welcome
Great testing procedures


12V on 30 and 12V at/on fuel pump wire when cranking

I think the issue is with ground or your testing method is in error. There is 12V while cranking but pump does not run.

That could definitely make sense. Any good places to start checking for ground? Tested continuity to battery ground terminal between the ground wire on the fuel pump and also the ground wire on the fuel pump relay harness bracket and they both showed continuity. Thanks!

 

[mikemj]

If i remember ,it should all rely on the purple wire.when turning the key the starter applies power to fp once started the altenator should take over

 

[mikemj]

check purple wire for power when starting and go from there

 

[alldodge]

That could definitely make sense. Any good places to start checking for ground? Tested continuity to battery ground terminal between the ground wire on the fuel pump and also the ground wire on the fuel pump relay harness bracket and they both showed continuity. Thanks!

30 has full time 12V and need to see if 87 gets power when 12V is applied to either 85 or 86. I say either because the manufacture could use either one for 12V and the other is ground.

Should be a yell/red wire on one side and black on the other. Apply 12V to yell/red and see if 12V is at 87.

If relay energizes and 87 has 12V than it's wiring to pump. If it doesn't than it's the relay or wiring of the relay, maybe the black ground wire

 

[Bt Doctur]

with a lot of fuel pump issues, I have changed them to the mercruiser design using a oil pressure switch, wired thru the cube relay.

 

[ScottinAZ]

sounds like your fuel system is very similar if not the same to my 1994 Cobra. (which became the SX drive shortly after). Here is a screenshot of the manual with the principles of operation, the wiring diagram and the troubleshooting section. Hope these help. Your wire colors sound the same as what I have, and what is in the manual.