5.7 VP running rough for first 10 mins

[winbasic]

Hi,

I've just returned from a day trip and for 99% of the day, the engine performed without any problems at all. We ended up doing about 3 hours total running time averaging 22 knots at around 3,400 rpm and averaging 40 litres per hour fuel burn. Temp was fine, oil was fine and no signs of anything being wrong.

When we started the boat, we idled for about 5 minutes then took about another 5 minutes to get out of the Marina at about 4 knots. When I put the throttle down to get up to the above figures, the engine appeared to be missing and generally running rough. We had to slow down to 6 knots for a speed restricted zone and after that, it was still missing and rough running probably for another 10 minutes before coming good.

Plugs are only 10 hours old and its got new oil and oil/fuel filters - no loose connections and as the first paragraph says, most of the day it ran fine. What sort of things should I be looking for to try and work out what's going on?

Thanks in advance!!

David.

 

[chiefalen]

Re: 5.7 VP running rough for first 10 mins

Fuel filters dirty ??

 

[Bondo]

Re: 5.7 VP running rough for first 10 mins

What sort of things should I be looking for to try and work out what's going on?

Ayuh,...

The Choke,+ it's adjustments....

Sounds like it might not be coming Off soon enough...

 

[winbasic]

Re: 5.7 VP running rough for first 10 mins

With regards to the fuel filters, if they were clogged wouldn't it run rough for the entire run rather than just the start of the trip? It had no problems at WOT either - I'm just basing this assumption on when I've had problems with fuel filters in cars and it seemed to cause starvation at revs.

Reg Choke - being EFI, is there anything I can do to verify the choke is coming off correctly? This sounds like it could be part of the problem as it does seem to have a bit of a 'running rich' feel to it which disappeared allowing it to run fine for the rest of the day.

One other thing is that I noticed I could start it fine first up but when I started it again a few times later in the day, I had to give it some throttle. Usually I can leave the throttle in its usual neutral position and start but later in the day it was just turning over so I had to advance the throttle a little to start it.

 

[Don S]

Re: 5.7 VP running rough for first 10 mins

You have MPI, no choke, chokes are on carbs.
You really need to do some testing to find out what the problem is.
Here is links to the EFI Diagnostic manual and the Manual corrections. Download both and have a read.

http://www.4shared.com/account/file/83596359/cdacddfb/7742218_EFI_Diagnostics.html

http://www.4shared.com/account/file/83596358/baabed6d/7742218_Manual_Corrections.html

 

[chiefalen]

Re: 5.7 VP running rough for first 10 mins

You have a fuel water separator, dump it in a clear container and leave it alone for a half hour to see if you have water in the fuel.

 

[winbasic]

Re: 5.7 VP running rough for first 10 mins

Thanks to everyone for the tips and information - looks like a diagnostics session is in order before the next outing!! I shall report back on what I find.

Thanks again!!

 

[winbasic]

Re: 5.7 VP running rough for first 10 mins

If I'm reading the manual correctly, then it sounds like having a scantool will make things a lot easier/clearer - if thats' the case, whats the general consensus as to the best scan tool to buy? Is it best to have a dedicated scan tool or one that plugs into a laptop?

 

[luv2b0at]

Re: 5.7 VP running rough for first 10 mins

I had a similar problem a few years ago and it ended up being a cooling system problem. As long as it was running, it would run. When you turned it off, it would have to sit for a while and start it at half throttle before it would run correctly.

Just a thought.

 

[winbasic]

Re: 5.7 VP running rough for first 10 mins

I had a similar problem a few years ago and it ended up being a cooling system problem. As long as it was running, it would run. When you turned it off, it would have to sit for a while and start it at half throttle before it would run correctly.

Just a thought.

Well you could be on to something there - I've just had to replace the seapump but the temperature isn't out of usual range. The other thought is that it might be fuel related as I think the fuel pump is noiser than it should be and that seems to be since I changed the fuel filter (filled the new filter with fuel before installing).

Don put a manual up for me but it refers to using a scan tool so hoping to get some info on what model and which type to use.

 

[Don S]

Re: 5.7 VP running rough for first 10 mins

Rinda Techmate scan tool will do the job nicely. You can get the software for a laptop but it's a big waste of money if you are only using it for your boat. I work on these things for a living and really haven't needed a laptop yet. Besides, you can't hardly read a laptop in the sun, and they are not as expensive to drop in the water or too the floor when sh** happens.
The downside, they don't look near as impressive as a laptop or the Volvo 2000 scantool

http://www.4shared.com/account/file/52421696/eb4489e5/Volvo_Drive_Chart.html?sId=qfPO3wd6vvS59Uww