4.3 GL starving for fuel

Alaboat

Petty Officer 2nd Class
Joined
May 21, 2015
Messages
129
UPDATE... took the boat out yesterday after picking up from shop and all was well; at least I thought so:grumpy: Ran fine cruising for about 30 minutes then it happened again. Died like it wasn't getting fuel. Got it cranked after a few tries and ran slow in a "no wake zone" for about 5 minutes and died again. Did this again another time. So I figured it was troubleshooting time, I had all day. I checked the carb by disconnecting the throttle linkage while engine was off and advancing the throttle manually at the carb. Fuel sprayed into carb like it should. While I was there, I looked at spark plug wires at distributor and didn't like the way they were routed with a little strain on wires so I disconnected one at a time to reroute and give some slack(just anal about stuff like that). Cranked back up and ran about 7 MPH with just enough speed to keep load on engine bow up to see how she ran and potentially pick up any bad fuel or water in tank while doing so. Ran like this for about 40 minutes, then picked up speed to about 22 MPH and 3k RPM's for another 30 minutes or so then picked up speed to about 30 MPH and 3.5k RPM's for another 2 hours or so. I killed the engine 2-3 times during this last several hours and let set several minutes to see if heat buildup while stopped would affect anything. I was never able to get the kill scenario repeat itself again. Total run time yesterday was about 3.5 hours mostly at cruising speed. I'm still scratching my head on this one. A little bad fuel or spark plug wire breaking down? Also talked to mechanic after all of this and he was puzzled as well and said sounds like a coil or other ignition component breaking down when it heats up but that it would be hard to diagnose without catching it in the act. sorry for the long post but maybe someone else can chime in.
 

Alaboat

Petty Officer 2nd Class
Joined
May 21, 2015
Messages
129
Talked to mechanic about that too. He seemed to think no since engine's not missing and runs good except for intermittent shutdowns.
 

Horigan

Chief Petty Officer
Joined
Jun 12, 2016
Messages
614
If it appeared to get better after fiddling with the spark plug wires and the cap, I would replace the cap, rotor, and spark plug wires. If something is intermittent between the coil and center of the cap, that could explain the symptoms.
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,582
I'm thinking electrical. It doesn't dies slow it just dies right?

If its electrical it can be many things
ignition switch
loosing ground
bad connection
kill switch
 

Alaboat

Petty Officer 2nd Class
Joined
May 21, 2015
Messages
129
I'm thinking electrical. It doesn't dies slow it just dies right?

If its electrical it can be many things
ignition switch
loosing ground
bad connection
kill switch
Alldodge, yes it just dies like I had ripped the kill switch loose, not a slow death.
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,582
That could be hard to find. Bring along a volt meter and when it dies see if there is power to the coil without turning engine off (leave it on)
 

Alaboat

Petty Officer 2nd Class
Joined
May 21, 2015
Messages
129
Back out with boat today and ran fine for about 45 minute cruise with no issues. I filled up before going out. Tank is 34 gallons and took about 22. Went out again this evening and boat died again several times while cruising at 25. This issue has me really bummed. Family says not getting back in that boat. Boat would crank after setting for several minutes. Still stuck on starving for fuel. I loosened fuel filter and tightened it back up and then boat will crank.
 

Alaboat

Petty Officer 2nd Class
Joined
May 21, 2015
Messages
129
Good question, normally when it stalls out and I look in the filter, it is not full, maybe a quarter full. Just now, I cranked it for a minute and shut it off. I removed the filter and it was completely full. That brings about a good point. Should filter be mostly full all of the time even at WOT? If so, then either trash in tank getting picked up at pickup or possibly fuel pump flaking out. Just doesn’t seem electrical with info from above. Thoughts?
 
Last edited:

Alaboat

Petty Officer 2nd Class
Joined
May 21, 2015
Messages
129
:blue:
That could be hard to find. Bring along a volt meter and when it dies see if there is power to the coil without turning engine off (leave it on)

alldodge, I did what you suggested and brought a voltmeter with me. When the engine died, I put the volt meter at the coil without turning off the key and still had 12 V at the top of coil.This last run of about 45 minutes resulted in several stall outs and kills. Then it ran fine for the next 30 minutes with no problems puzzled
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,582
The fuel filter should be completely full of fuel at all times, idle to WOT and when the motor is shut OFF.

With the filter not being full, you either have a weak pump or restriction. The number one cause of a restriction is the antisiphon valve on the tank. Its a barbed fitting that the rubber fuel line connects to that goes to the filter. It should allow fuel to pass with a slight sucktion from the pump. Some times they get crud built up and pass very little.

anti siphon valve.png

weak pump can also cause the issue, because in simple terms it doesn't suck very well. If everything is clear, including the pickup tube, then need to check fuel pressure (3-7 psi)
 

Alaboat

Petty Officer 2nd Class
Joined
May 21, 2015
Messages
129
Had the boat in the shop earlier this month and they concluded it was anti siphon valve and fuel pickup in tank and both were replaced but I’m still having the same issues. Not sure if they checked fuel pressure or not, not likely. So you mentioned a weak pump. Could a weak pump work fine sometimes for like several hours and then intermittently just stop and then start working again in a few minutes? That what I’m experiencing.
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,582
Many boat shops just throw parts at the problem instead of actually finding the issue. Main problem is they don't refund when their wrong

Normally no but the pump could be heating up and start causing an issue, only way to know is measuring pressure when it happens
 

Alaboat

Petty Officer 2nd Class
Joined
May 21, 2015
Messages
129
Many boat shops just throw parts at the problem instead of actually finding the issue. Main problem is they don't refund when their wrong

Normally no but the pump could be heating up and start causing an issue, only way to know is measuring pressure when it happens

You got that right, I won’t say how much they charged for this”repair” but I feel they still owe me for fixing this issue. More discussion will be had with them but likely just venting.
 

Alaboat

Petty Officer 2nd Class
Joined
May 21, 2015
Messages
129
Another bit of data to add to this lengthy thread, when engine stalls out, it will consistently restart if I unscrew the filter and retighten. To me, this indicative of trash in tank getting sucked up to fuel pickup in tank and stopping fuel flow. Once filter is unscrewed it allows trash to fall away from pickup and begin flowing again. Does this make sense or does it still sound like fuel pump? Went out again a little while ago and 2 stalls in about 45 minute ride. Just cranking right after stall does not crank it but R/R fuel filter cranks right up.
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,582
Looked thru the thread to make sure no one mentioned about when it stops running, remove the gas cap and listen. If you hear air being sucked in then your tank vent line is clogged up. This would also go along with removing the filter, it to would let ait get sucked back into the tank

Its normal that someone would mention this including my self, but guess just to many threads going on
 

Alaboat

Petty Officer 2nd Class
Joined
May 21, 2015
Messages
129
Looked thru the thread to make sure no one mentioned about when it stops running, remove the gas cap and listen. If you hear air being sucked in then your tank vent line is clogged up. This would also go along with removing the filter, it to would let ait get sucked back into the tank

Its normal that someone would mention this including my self, but guess just to many threads going on

Yes, I checked vent line and it’s free and clear.
 

Alaboat

Petty Officer 2nd Class
Joined
May 21, 2015
Messages
129
Then it makes no sense and we need some fuel pressure readings

Agreed, just got back from an hour long cruise in choppy waters from all the Memorial Day traffic and all was well. I dumped the fuel filter when I got back three separate run/dump cycles and very little sediment and a fingernail-sized ball of water at the bottom. Bizarre that if it’s the pump that it would be all good for an hour with no hiccups. But then again, I’m no mechanic. Thanks for all the suggestions.
 
Top