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Volvo penta 50 litre rev problem

john_g

New member
"We live in the tropics and ha

"We live in the tropics and have a 3 year old volvo penta EFI gas engine (GXI model), low hours, with sterndrive in a 28 foot sportscruiser. Since purchase 1 year ago there has been an intermittent (now constant) problem of not revving above 3000-3500 RPM when the boat is under load or when engine has been running for more than 10 minutes. Engine runs smoothly, not obviously fuel contamination. Any suggestions?"
 
"John, it could be a plugged u

"John, it could be a plugged up fuel filter or other partial obstruction in the fuel line or possibly a bad anti-siphon valve at the tank. It sounds like you are getting a constant supply of fuel,always getting enough to keep running at partial throttle, just not enough to feed the motor and support higher rev's when you open throttle up all the way. Just my 2 cents...."
 
"Matt, Thanks. We have changed

"Matt, Thanks. We have changed the fuel filters twice with no significant improvement, but you may be right that there is another fuel supply problem. We are also wondering about the engine sensors and electronic control. John"
 
Thank you 'Just in Time&#3

Thank you 'Just in Time'. No alarms have activated. The next test we have planned is a fuel pressure test. Also we are checking the replacement cost of the engine sensors and the electronic management system. John
 
"no plug it into a diagnosis s

"no plug it into a diagnosis system
this will tell you if any codes went off

let us know the results, before you replace anything"
 
"Thank you again 'Just in

"Thank you again 'Just in Time'. I greatly appreciate the excellent advice that I have received. A Volvo diagnostics system was connected and the boat tested in the ocean(Coral Sea)under load - but no abnormality was detected. The testing mechanic had said that a sensor problem had not been excluded, but I learnt today that a sensor problem should have shown up (and also no alarms went off). Apparently the alarm system does not usually fail. So we are awaiting the fuel pressure test (hopefully this week)and we wonder if it is a fuel pump or fuel line problem. John"
 
"Thanks again 'Just in Tim

"Thanks again 'Just in Time'. Interesting, I was told later that his testing unit could not check fuel pressure. I guess we will just have to wait now for the 'next' pressure test. John"
 
"Thanks "Just in Time'

"Thanks "Just in Time'. You are correct as the mechanic only used a hand held device like a PDA (he said today that he was not sure what it was called). The Diacom site is interesting and the PC marine software looks to be what we really need. For the pressure test he is planning to ?screw a gauge into the side of the fuel pump, but he has said that he is not sure what the normal pressure should be. Would you happen to know where I may be able to check on this information. Thanks. John"
 
you need to find a new tech wi

you need to find a new tech with volvo certifaction. This tech is going to blow your motor up

It is in the factory manual for pressure

i think 44psi on the high side and i forget the low side
 
Thanks. You are quite right. I

Thanks. You are quite right. I read about MEFI last night and came to the same conclusion. I will keep you informed. John
 
"Thanks again 'Just in Tim

"Thanks again 'Just in Time'. I saw on the Rinda site last night that our Volvo should have the MEFI-4. I would appreciate the pdf if it's not too much trouble - '[email protected]'. I'm not a mechanic but am certainly learning about EFI. Your help has been invaluable. John"
 
"Hi! John, I have a 2004 Glast

"Hi! John, I have a 2004 Glastron 25 with 5.7 EFI engine. My engine has almost the same problem like yours. On 6-7 Miles/Hour runs smooth, as soon I speed up to only 10-12 miles/hour the engine start braking up! Like wroom-wroom... I'm a retired automechanic, right away I changed the fuel filter. Same problem. Than I did run the engine from a temporary fuel can to eliminate the fuel tank or suction pipe. Got not better. I have installed a new fuel pump, this kit of primary and high pressure pump cost $690 plus labor, because a mobil boat mechanis did it for me. Did not get better, the boat mechanic dissipeard. Dos not answers my call anymore. Now I realised that must be electronic problem...but nobody in my neigborhood has a scanner. THIS MUST BE A COMMON PROBLEM WITH THESE ENGINES.
This repairs going on for 4-5 months, I'm verry dissapointed. I have fixed cars all my life. Now retired, no scanner, no tools, no idea what to do... The ignation system is to complicated to service without a scanner."
 
Do u understand MEFI 4?
read


Do u understand MEFI 4?
read up on it
You will need the scan tool
the VST tanks need to be cleaned
 
"I'm not going to buy a sc

"I'm not going to buy a scanner just for this trouble, meantime can't find a mobile mechanic in my neighborhood, Punta Gorda, SW Florida. Looks like the marine EFI totally diferent from cars.
What is VST stands for?
Thanks for previos prompt answer!"
 
"Joseph,
We are still looking


"Joseph,
We are still looking for a suitable mechanic for our problem here in Australia to diagnose the problem. 'Just in Time' has been very helpful to us.
John"
 
"vst
vapor seperator tank


"vst
vapor seperator tank

the mefi is the same as in the gmc/gm cars
just have a little more sensors

Joseph Hajdu post this ? on thehulltruth.com, a ton of guys are from fl

the scanner is 600, i would loan it to u but a little too far away"
 
I am running twin 5.0 gi volvo

I am running twin 5.0 gi volvo lots of trouble. also live in punta gorda. what is your email address
 
Am slowly sorting through the

Am slowly sorting through the problems with our 5.0 rev problem. With a new mechanic we found that the fuel pump pressure was normal. Testing showed a faulty ignition coil and also one faulty spark plug. The coil and all plugs were replaced two days ago. The hull and prop growth will be cleaned today and we will take the boat for a run next weekend. The engine compression and timing have not been checked yet.
 
"Looks like my problem, after

"Looks like my problem, after a year of agravation has been solved.
Like I wrote earlier, on the beginning the engine (2004 Volvo 5.7i)was braking up. A new fuel pump did not help. ($690+labor) NOW finally did not start at all. This way it's easy. A new fuse box with all new relleys has been intalled and that's it. The fuse box is a sealed unit. Inside probably has some printed circuit and/or condensors.
In Punta Gorda neighborhood I descovered a great Volvo-Penta specialist."
 
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