Fuel pump, relay, or bad electrical connection

[jclarke2899]

Hi all,

I have a 1998 Volvo penta/OMC 5.0GL (502BPBYC). I went to the lake this weekend, it started fine at the dock and idled for about 15 minutes then it sputtered and shut down on me. I took the carb cover and flame arrestor off to realize fuel was not being pumped into the carb when cranking or advancing the throttle. I assumed my fuel pump was going bad. Kept pumping and trying, it eventually fired up, was running fine and drove for a good 35 minutes at cruising/WOT speeds with no issue whatsoever. Went to slow down through no wake zone, and it sputtered and died again and could not fire it up. At this point, it was too hot, so we swam around for awhile and tried firing it up again when we were ready to leave to no avail. Was getting towed in by a buddy and I tried it again and it fired up. Got it back to the house and put a meter on the relay pins and had no voltage. Wasn't sure which pins to check at the time, but checked them all and didn't register voltage. I immediately went to my battery and noticed the positive cable was loose by about 2 turns. I tightened it down and have started it on flusher and idled it about 12 times and it has not happened again. Could it really be this simple, and if so, how would my starter crank fine, and it not get power to my fuel pump? Do fuel pumps typically die intermittently, or do they normally work or don't? I hear all the stories of boats being money pits, so I'm always first to expect the worst.

Thanks,
Jamie

 

[jclarke2899]

Re: Fuel pump, relay, or bad electrical connection

Was getting towed in by a buddy and I tried it again and it fired up.

Meant to say, it fired up and ran good idling, cruising, WOT, until I got back to the dock to bring it back to idle and it cut out again.

 

[jclarke2899]

Re: Fuel pump, relay, or bad electrical connection

bump....anybody have an idea or had the same problem?

 

[jrampey]

Re: Fuel pump, relay, or bad electrical connection

I'm chasing the same problem. I changed the fuel pump - still there. Ouch, an expensive parts change! Now I'm questioning the oil pressure sensor. But before I change another part without knowing I've wired up a small light spliced into the hot wire to the pump. If the light goes out - I'll know I'm losing power to the pump.

 

[spktho]

Re: Fuel pump, relay, or bad electrical connection

Sounds like you are the right track. I know a little about voltage to the fuel pump, but you may already know. When you crank the engine, voltage comes from the starter. On my older 4.3 Volvo Penta, after the engine is started, the voltage to the fuel pump comes from the alternator through a relay mounted behind the engine. You need to trace and check the voltage for both paths since it sound like you may issues with both.

 

[jclarke2899]

Re: Fuel pump, relay, or bad electrical connection

Sounds like you are the right track. I know a little about voltage to the fuel pump, but you may already know. When you crank the engine, voltage comes from the starter. On my older 4.3 Volvo Penta, after the engine is started, the voltage to the fuel pump comes from the alternator through a relay mounted behind the engine. You need to trace and check the voltage for both paths since it sound like you may issues with both.

Do you think it's possible that the loose positive cable was the only problem, I've started over and over and it hasn't done it since? That just sounds way too easy to have been the problem, not to mention doesn't explain why it ran fine at cruising and WOT and didn't die again until I was at idling speed. If it were a voltage problem, I would have expected more of a problem at WOT, as I'm assuming the pump is running faster or at least constantly. Won't be on the lake again until the weekend, plan on taking some extra wire for a jumper if I need it to get back in.

 

[spktho]

Re: Fuel pump, relay, or bad electrical connection

The engine wouldn't crank if the battery cable was too loose. Hopefully by checking the other wires you may have cleaned some connections that may have been causing the problem. It's hard to tell what to do when you can't reproduce the symptoms. Let us know how it turns out.

 

[jclarke2899]

Re: Fuel pump, relay, or bad electrical connection

The engine wouldn't crank if the battery cable was too loose. Hopefully by checking the other wires you may have cleaned some connections that may have been causing the problem. It's hard to tell what to do when you can't reproduce the symptoms. Let us know how it turns out.

Isn't that how it goes most the time, can't reproduce the symptoms in the driveway, wait until you're a few miles from the boat dock and THEN it happens.

That's where I'm having the trouble, the starter always cranked fine, so I assumed I was getting voltage. The only reason I checked the battery is I wasn't getting 12v constant voltage at the relay pins after reading some posts Don S. had posted on here before describing how to check it.

You could be right that it was a bad connection at the relay, I know I won't be on the lake again without a jumper to see if it is indeed an electrical problem. I did notice my fuel pump seems to run extremely hot to the touch, I never had reason to notice it before, but not sure if that's actually a problem or not. I've also ordered a new fuel filter, just because it needs replacing, not that I think that's the problem.

I'm still torn if this is an electrical problem or a fuel problem. As mentioned, once started, it ran fine idling for a few minutes, then it ran great at cruising and WOT for over 30 minutes, but only when I slowed down to idle did it die.