Runs Great. Then Won't Start. Next Morning Starts Right Up.

[cooper-c]

The past 2 weekends the same situation has happened. Engine is a Volvo Penta GM V6 4.3L fuel injected sterndrive. When I arrive to the lake, boat fires right up. Runs great. I am able to turn off engine. Starts right up again a few more times. Then after an hour or so and engine has warmed up, I turn engine off and then it cranks but won't turn over. I had 2 good batteries. I get towed in, camp overnight, and the next morning it fires right up. Temp and oil pressure seem fine when running.

After the 1st weekend, my mechanic changed out spark plugs and fuel filter. The 2nd weekend it fires right up first thing. Run it off and on for a few hours. Then it won't turn over. Get towed in. Camp overnight. Next morning fires right up. Once it is running it stays running but after engine warms up, if I kill engine, then it won't turn back over. Ran great last summer. Newer engine stored indoors over winter.

Spoke with my mechanic, I asked if it could be vapor lock in fuel line and filter. He is leaning towards weak fuel pump. Any thoughts I can pass along to my mechanic will help us. Thank you.

 

[Fair Weather]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

Pull a plug wire off when its not starting up and check for spark with a screw driver, you just stick the screw driver usually a phillips fits nicely, in next to the contact, hold the screw driver 3/8 inch from the engine and crank the engine over, you should see a nice blue spark, then you know its a fuel issue, if no spark is presient then you have a electric problem!

 

[cooper-c]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

Pull a plug wire off when its not starting up and check for spark with a screw driver, you just stick the screw driver usually a phillips fits nicely, in next to the contact, hold the screw driver 3/8 inch from the engine and crank the engine over, you should see a nice blue spark, then you know its a fuel issue, if no spark is presient then you have a electric problem!

Thanks for the reply. Changed plugs and have spark. I am thinking it is fuel issue. Mechanically boat runs great. Just won't start after running and heating engine up until next morning.

 

[Don S]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

What's the full model number or serial number of your engine. Too many different EFI systems to guess at.

Was it really hot that day? Possibly vapor lock? Could also be a plugged up fuel tank vent, or _________.

HOW TO: Testing your boats fuel system.?/ 283269

 

[cooper-c]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

Don S., Thanks for the reply. Model No. 4.3GIPBYCCE V6-200. It has been hot. Is there a way to test for vapor lock? And is there an easy way to get boat started again if I do get stuck on lake again if it is vapor lock? If I don't turn off engine, it will run all day. Thanks again.

 

[Don S]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

Go for a good run on a hot day, get it warmed up. Then when you stop, open the engine compartment to let the hot air out.
Then see if it will start after sitting for 15 or 20 minutes.

 

[cooper-c]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

I will do that on Saturday. Thanks.

 

[cooper-c]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

Same problem this weekend. Started up ok when engine was cold. I ran it for a couple of hours. Turned off engine. Then let it sit for 2 hours while we ate dinner. Outside temperature cooled. Engine temp ranged from 110F - 160F while running. When I shut it down, I opened engine compartment. Engine temp was around 120F when I shut it down but not hot to touch. Went back to start it up again, cranked but didn't turnover. Next morning after a few minutes of cranking, it started up. I ran it for 3 hours without shutting off. Then back at dock, turned it off and wouldn't restart. I'm now thinking it could be weak starter or weak fuel pump. And if weak fuel pump, do I need to replace both high and low pressure pumps?

 

[Don S]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

cranked but didn't turnover.

To a mechanic, those words mean the same thing. Cranking/engine turning over using the starter motor.
Starting and running means the engine starts and/or runs.

When you crank it, does the engine fire at all on even one cylinder now and then, even act like it's wanting to start

I'm now thinking it could be weak starter or weak fuel pump.

Grabbing at straws here? Does the engine crank over normally? normal speed? does it sound like it's spinning the engine as fast as it does when it's cold?

The only way I would think it was fuel pumps is if they weren't running at all. Do the pumps run for 2 seconds when you turn the key to the run position when it doesn't start?
Does it have spark from the coil when it doesn't start?

 

[cooper-c]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

When it doesn't start, the engine sometimes seems like it fires on a few cylinders then dies. It does act like it wants to start sometimes. Starter motor cranks at normal speed when hot. So maybe it's not starter.

The pumps do run for 2 seconds after I turn key to run position before cranking.

 

[Don S]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

I suppose weak pumps could do it, but before I spent a lot of money on pumps I would sure be doing some pressure tests on the fuel pumps when it won't start. I would also be looking at a diagnosic scan tool to see what everything looks like. Possibly some sensor out of range. Not something that would set a code, but enough to keep it from starting.

One other thing, when it doesn't start, have you tried going to WOT while cranking to see if it starts like that? That would indicate a flooded engine.

 

[cooper-c]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

Thanks Don. Tried WOT to make sure it wasnt flooded. I will let you know what eventually solves the problem.

 

[cooper-c]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

I think I have narrowed it down to fuel pump. Do I need to replace both low and high pressure pumps?

 

[Beaubm01]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

I think I have narrowed it down to fuel pump. Do I need to replace both low and high pressure pumps?

Curious to hear if you've fixed this as I'm having similar problems. I have found that when it does not start and I loosen the gas filter it clears the vapor lock and it starts right up. I just don't know what's causing the vapor lock in first place.

 

[cooper-c]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

I'm replacing both low and high pressure fuel pumps this week. I'll let you know.

 

[Beaubm01]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

I really appreciate the info. I hope this works!

 

[Beaubm01]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

Was wondering how the pump replacement went? Fix the problem? I will hopefull be working on mine this weekend.

 

[es135]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

@ Beaubm01... I had the same problem. Thought it was vapor lock because my pump was running so hot. I replaced the fuel pump ($700) but that wasn't the issue. I had two other problems: 1) the fuel pressure regulator was shot. It allowed the engine to start fine on cold starts but caused problems on warm starts. I replaced it with a 59 psi regulator from BWD (part# 24035) for $69 instead of the volvo $200 one. The only difference is the hose connector sticks out the back of the regulator instead of angled upward. Had to get a 12'' of of vacuum hose at NAPA (69 cents) to replace the existing vacuum hose.

Problem #2) The fuel pump was running very hot and whining. The water cooling line running from the block to the back of the fuel pump was completely clogged with sand/muck. Cleaned it out with a coat hanger and pump runs cool now (no whining). 'Need to check both the incoming and outgoing cooling hoses for blockage.

 

[Beaubm01]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

Thank you! I have a good exit stream of water from my motor so I assumed there was no blockage. I will pull the pump off and locate the pressure regulator. If you learn anything else, please pass it along. I will report back

 

[es135]

Re: Runs Great. Then Won't Start. Next Morning Starts Right Up.

I'm not sure exactly what engine you have but mine is a 4.3GXI and I didn't have to pull the pump off to get to the regulator. The fuel pressure regulator is on the fuel rail (on top, port side of engine). It's just held in with a clip and pops right out. Did you say your fuel pump is running hot?