Volvo 5.0gfi High RPM Problem

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greendoc

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Sep 12, 2007
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Hey Guys,

I've got a 1999 292 Commodore w/twin VP 5.0gxi 220hps that is running slow and hoped maybe some of you could help me and my mechanic trouble shoot it. Bought the boat back in April. I have run it up to 42mph at 4880rpm with no trouble as little as 4 months ago. More recently, when I push the throttle past 3800 rpm the engines start to slow and loose power instead of the other way around. Currently i'm able to do 35-37mph at around 4000rpm max.

We've checked electrical. Batteries run low, but we think it's normal at 12.2-12.5v. Alternators are good. We've cleaned the fuel filter and checked the strainers. Hooked a computer up to the engines and everything seems to show healthy.

One big thing; ever since I bought it the engine gives off significant gas/smoke at low rpm to the point that even the blower doesn't always help. (well, it's probably their at high RPM but the wind kicks it away)

The dealer i bought her from did a full tune-up which appears to be decent, although spark plugs may be spaced slightly off.

Anyways, we've looked a good bit and don't see a smoking gun and wanted to ask the 'Regal experts' what they might think of and if you all have any ideas for me.

Thanks a ton for the responses!
 
Sounds like a fuel issue.

Some things to check.

Fuel filter
kinked fuel line
anti siphon valve
Carb gummed up due to ethanol issues
dirty spark arrestor

What color is the smoke at low RPM?
 
What Rommer said.

Could also be water in the fuel depending on how fast you burn the fuel.
 
greendoc

when you run the engine up until it starts cutting out, if it is a fuel issue you should see some change in the temp as it leans out. you can check the temp with a hand held laser at the riser. have you done anything to the engine compartment that might restrict the air flow? easy to check open the hatch while underway. does your boat have two fuel tanks? if so is the problem identical on both motors fuel sources? the smoke you mention i assume is coming into the engine compartment from the motor. if this is blowby that is not being consumed by the air intake, your motors may be tired and ready for an overhaul. have you done a compression check on the engines? was the tune up before or after the change in speed? has anyone checked the timing on them?
 
If the fuel is good and the compression (or leak down) test checks out good, I would also check the oil filter to make sure the engine isn't eating itself up... Pull the filter off and pour it out looking at the oil coming out of the filter. If you see glitter - you have a problem.

just my $0.02
 
Hi Guys I had a similar problem on our 290 Commodore this summer , The coil wire was bad !!! Drove me nuts for a week ,Then one night I was checking for a cause and I saw the coil to distributor wire arcing . $4.95 later that port engine never ran better . This winter it gets all new wires. Hope this helps, Ed
 
Ummm, not to open a can of worms but $4.95 for a coil? Sounds like you are using an automotive coil. Better hope you never have a fire or worse because your insurance may be void. You really MUST use marine rated/certified parts in a boat, for your protection and those around you as well. Ignition protected parts can be the difference between life and death if you ever develop a fuel leak.

What area do you boat? I'd like to avoid the bang if possible!
 
quote:
Originally posted by vic33004

greendoc

when you run the engine up until it starts cutting out, if it is a fuel issue you should see some change in the temp as it leans out. you can check the temp with a hand held laser at the riser. have you done anything to the engine compartment that might restrict the air flow? easy to check open the hatch while underway. does your boat have two fuel tanks? if so is the problem identical on both motors fuel sources? the smoke you mention i assume is coming into the engine compartment from the motor. if this is blowby that is not being consumed by the air intake, your motors may be tired and ready for an overhaul. have you done a compression check on the engines? was the tune up before or after the change in speed? has anyone checked the timing on them?

Click to expand...


The boat does have two fuel tanks. We have confirmed the problem with both motors. The temp gauges don't show any difference at speed, but i may utilize a thermostat/laser to test if neded.

The smoke doesn't seem to be in the engine compartment but instead tends to be blowing out of the exhaust. I could be wrong on that and will check tomorrow at the boat.

The motors have confirmed 104 hours on each of them, so even though they're 8 years old, very low hours. The boat was salt-water kept the first 4-5 years of its life and the original owner brought it up to Lake Norman where I eventually bought it (freshwater lake).

The tune-up was a good 3-4 months BEFORE the change in RPM and speed.

I need to confirm the timing and compression check. Does anyone know if a computer diagnostic hook-up would show compression or timing info?
 
quote:
Originally posted by folieadeux

What Rommer said.

Could also be water in the fuel depending on how fast you burn the fuel.

Click to expand...


I haven't drained the fuel tanks below 1/3-1/2 tank since purchasing the boat with a full tank of gas back in April. Every 2-4 trips out, I drop $120-$150 or so in the gas tank to keep her fresh. Could the older fuel cause anything like this?
 
quote:
Originally posted by rommer

Sounds like a fuel issue.

Some things to check.

Fuel filter
kinked fuel line
anti siphon valve
Carb gummed up due to ethanol issues
dirty spark arrestor

What color is the smoke at low RPM?

Click to expand...


smoke at low RPM is clear to light gray ??
 
Sorry, but I'm very confused.

You said the following 2 things.

"One big thing; ever since I bought it the engine gives off significant gas/smoke at low rpm to the point that even the blower doesn't always help."

and

"The smoke doesn't seem to be in the engine compartment but instead tends to be blowing out of the exhaust."

I guess it is the blower thing that confuses me. Why do you think the blower would help with exhaust smoke? The exhaust is not leaking in the engine compartment is it? If so you are choking the engines and potentially killing yourself! Hope I'm wrong and misunderstanding what you are saying.
 
I agree with Rommer, if smoke is coming in the engine compartment it can choke the engines and the volume of exhaust at higher rpm might be just enough to overwhelm the blower. Try running with the engine compartment slightly open to vent it and check for improvement and leaks. You have to focus on things that can affect both motors at same time... fuel and air are about the only two things that both engines share. Also, a lot of marine growth on the hull can limit speed enough to hold the rpm back too.
 
Rommer , The 4.95 was for the coil wire ! Here we go with the engineers again!!!, Oh yea I boat In N.J.
 
My bad, but would you rather I just ignored a potential problem or speak my mind and hopefully keep someone safe? I'd much rather err on the side of caution.
 
This time I will side with Rommer.

My friend recently bought a used boat and I sugested he remove the out drive as part of his inspection.
Low and behold an automotive U joint of questionable quality.
Now he is checking for other substandard parts.

Boats are not cars that can be pulled over to the side of the road and those of us who operate single screw boats need 100% reliability.
Safety and reliability must always come first.
 
Update:

My mechanic and myself have now done just about everything 'normal' to the boat, including all the items aforementioned on this forum. In addition, timing adjusted from 12 degrees down to 8 degrees, etc. The starboard engine's spark plugs were fouled and replaced but the biggest thing still seems to be that it runs too rich at idle, causing the aforementioned smoke problem, but the ignition system all seems fine...

ie their is no smoking gun so to speak :)

My mechanic wants to take it for a drive with me Tuesday or Thursday and hook the computer up to the engines while running it to get a fuel pressure check, but otherwise we are at a loss.

Any other ideas guys?

Thanks!
 
Doc;

if you are fouling the plugs at low speed, it could be an ignition related issue. if all the plugs are fouled, my guess is you may be getting a weak spark upstream of the distributor, or you are right on that it is simply running too rich at low speed. since the problem is on both engines neither of these scenarios seems likely. it would be more likely that what ever is causing the trouble is common to both. my first step would be to change the fuel filters. when you pull them off, pour the contents into a glass so you can see if any water or debris separates out. your engines may also have a very small last chance fuel filter at the carb in addition to the larger primary filters. the plug fouling and high speed drop off may be unrelated if the filters are fouled you are starving for fuel at the top end. do you run the boat for extended periods at dead idle getting in and out of your marina? if so, you may want to change up to a hotter spark plug in the range of temps reccomended for that motor. it might be worth confirming that the plugs you have installed are in fact the correct ones with the correct gap.
 
It may be well to get fresh fuel in at least one of you tanks, from what you say, it sounds like the fuel that was in it when you bought the boat has never been allowed to run down very far. You might try drawing fuel from just one tank to get it empty then run both engines on fresh fuel. Old fuel can cause an engine to really run rotten if at all.
 
As always, thanks for the comments. I'll be out at the boat later today or tomorrow and will have my mechanic up their with me this week...Will let everyone know what I find out!
 
Update:

My mechanic went for a drive and the fuel flow meter showed absolutely NO problems.

An interesting problem with the Regal 292's 12v battery system was the voltage. The readings we were getting were around 11.5-12.3v always on my boat, which seemed kinda odd. If you checked voltage at the alternator and BEFORE the battery isolator, you would get 13+ volts as you should.

Anyways, we re-wired the batteries around the battery isolator and were able to get the system up to 4600rpm and 40.4mph; not bad but STILL seems kinda sluggish for twin 5.0gxi volvo pentas on the 29 foot 292 commodore.

QUESTIONS for everyone though:

#1) What experience do you have with TOP performance on 29-30 foot regals in regards to speed and RPM - please list model # and year when answering unless you happen to have stats for my 1999 Regal 292.

#2) Anyone else had any problems with the factory battery isolators?

#3) Does anyone know how to 'LEAN' out the fuel mixture at idle; it just runs too rich and I don't know if their is a way to change that.

Thanks for the continued responses!!
 
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