Annoying beeping help! (mercruiser mag mpi 5.7)

[jamespjackson95]

Hey guys, I want some help diagnosing a boat. The boat is a 2000 with a 5.7 mag mpi 5.7. It came into my shop and it was said to be running fine. The customer wanted the water pump impeller, and the battery cable connections replaced (they were corodded bad). Anyways I changed the impeller and the cable ends and started the boat up on the hose to ensure it was still pumping water fine. It was pumping water great. I let the boat idle for a while and then gave it a little throttle in neutral. At approx 4k rpms, the engine sort of skips. (the tach did not work, this is just a rough guess) It doesnt backfire, or doesn't shut off, just kind of skips... sort of like its missing. So i called the customer and told him and i tried doing a tune up. Replaced the plugs first with no change, replaced the dist cap and rotor with a sierra kit from west marine. Also did plug wires. When i first started the boat up it idled fine... when giving it throttle to see if it skips, the boat beeps 3 times, 1 second beep, 2 seconds off, 1 second beep, 2 seconds off etc.... the boat would only do this at higher rpms (approx 2k), it would not do the beeping while idling, and the boat would still skip at approx 4k rpm, just like before... so i then checked the fuel filter (separator) and it had a lot of what looked like muddy water in it... i dumped it all out and then installed it without filling with gas.... the boat started and immediatly beeped like before at idle, and then shut off after about 10 seconds. I went and bought a new fuel filter and installed full of gas.... now it only beeps at 2k rpm like before... it does not beep at idle.... gear lube reservior is full... when i changed the impeller i pumped gear lube in the bottom untill i saw it come out the top hole, then put the plugs back on.
Any input here guys? Want to check out some simple things before i fork out money for the scan tool.

 

[thumpar]

Does it have a water pressure sensor? 2k RPM is to much while on muffs.

 

[Tail_Gunner]

I really don't what to say here as polite as i can say this im not sure your up to this. You were probably hitting the rev limiter at 4800 rpm why would you rev it that high in the first place. That annoying alarm is the ecm saying you have a problem and yes you need a diag tool.

 

[jamespjackson95]

I highly doubt it was the rev limiter. Didn't seem like I was nearly that high. I'm gonna drop it in the lake and see if anything changes. Keep the comments coming.

 

[Thalasso]

You shouldn't be revving that high, period while on muffs. Your a mechanic? You should know what the beeps represent.
4000rpm's, i doubt there was any water for cooling

 

[Tail_Gunner]

I highly doubt it was the rev limiter. Didn't seem like I was nearly that high. I'm gonna drop it in the lake and see if anything changes. Keep the comments coming.

The mere fact you would take it to the water with ecm reporting a error is....ok have a read before you leap

https://drive.google.com/file/d/0B3w...Z2s/edit?pli=1

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[alldodge]

Hey guys, I want some help diagnosing a boat. The boat is a 2000 with a 5.7 mag mpi 5.7. It came into my shop and it was said to be running fine. The customer wanted the water pump impeller, and the battery cable connections replaced (they were corodded bad). Anyways I changed the impeller and the cable ends and started the boat up on the hose to ensure it was still pumping water fine. It was pumping water great. I let the boat idle for a while and then gave it a little throttle in neutral. At approx 4k rpms, the engine sort of skips. (the tach did not work, this is just a rough guess) It doesnt backfire, or doesn't shut off, just kind of skips... sort of like its missing. So i called the customer and told him and i tried doing a tune up. Replaced the plugs first with no change, replaced the dist cap and rotor with a sierra kit from west marine. Also did plug wires. When i first started the boat up it idled fine... when giving it throttle to see if it skips, the boat beeps 3 times, 1 second beep, 2 seconds off, 1 second beep, 2 seconds off etc.... the boat would only do this at higher rpms (approx 2k), it would not do the beeping while idling, and the boat would still skip at approx 4k rpm, just like before... so i then checked the fuel filter (separator) and it had a lot of what looked like muddy water in it... i dumped it all out and then installed it without filling with gas.... the boat started and immediatly beeped like before at idle, and then shut off after about 10 seconds. I went and bought a new fuel filter and installed full of gas.... now it only beeps at 2k rpm like before... it does not beep at idle.... gear lube reservior is full... when i changed the impeller i pumped gear lube in the bottom untill i saw it come out the top hole, then put the plugs back on.
Any input here guys? Want to check out some simple things before i fork out money for the scan tool.

As others have mentioned you never run a motor that high on muffs. The manual states you should not exceed 1500rpm, over 4000 is way to much. You exceed the rpm so much you should replace the impeller again because it more then likely has been damaged.

If this was your boat then I would look at it as everyone makes mistakes, but you said your "Customer"

 

[jamespjackson95]

Guys when I am running the boat at a high rpm, it is for just a second or two... There is no way that the impeller which constantly is being supplied water through the hose would burn up, or that the water supply hose would collapse in that short of time and lead to an overheated engine. I could understand that if I left it there for an extended period of time... But for a just a second I believe it is fine. The boat temps are great, measured via gauge and infrared gun... So I do not think there is any issue with the cooling system. What I am trying to diagnose is the beeping and skipping/stuttering... Without having to buy the scan tool... The boat runs great other than that.

 

[Fun Times]

Hi there jamespjackson95, I get what you are doing by quickly revving the engine up to near max RPM and immediately bringing it back to idle a few times to try and get an idea of what the engine may sound or act like at higher RPM. Sometimes the problem with free revving like that may not be able to tell you everything you'd like or need to know about a marine engines true condition because it really doesn't take much engine power to rev it up that high.
It's just best to run the engine under load (lake or propshaft dyno) to get an accurate diagnostics starting point. Also free revving an engine up to near max RPM is highly frowned upon due to the possibly of moderate to severe internal engine damage along with a possibility of a weak garden hose collapsing from the impeller sucking it closed and/or low city water pressure.

Since the tachometer was not working and the description of the engine having a miss anywhere near 4000 RPM sure indicates to us that you were hitting the engines rev limiter (< it's very easy to do) which is typically about 150 RPM over the max RPM range and depending on engine model, it could be accompanied by a warning horn. Usually basic engine specs can be found on top of the engine such as the flame arrestor sticker for example. The rev limiter resembles a skip or stuttering affect.

Since you found water in the fuel system, you'll want to run the engine on a separate fuel supply such as an outboard fuel tank and see if the engine runs better "while on the lake".

Also to help know what engine features/sensors this engine model has to offer, we'd need the engine serial number to help try and give you a place to inspect. For example, some engine models around that time offered a fuel pressure sensor that could sound the warning horn should it sense low pressure but this sensor was short lived. There are many other sensors that may sound the warning horn as well but without know what model, it's all a guess.

Is the stern drive an Alpha or Bravo drive? Are you typically an auto repair shop helping out a boat owner or are you getting into boats?

 

[JustJason]

Hey guys, I want some help diagnosing a boat. The boat is a 2000 with a 5.7 mag mpi 5.7. It came into my shop and it was said to be running fine. The customer wanted the water pump impeller, and the battery cable connections replaced (they were corodded bad). Anyways I changed the impeller and the cable ends and started the boat up on the hose to ensure it was still pumping water fine. It was pumping water great. I let the boat idle for a while and then gave it a little throttle in neutral. At approx 4k rpms, the engine sort of skips.

:facepalm::facepalm::facepalm::facepalm::facepalm:

Dude..... If you have customers and you are charging money, you need to buy a scan tool and stop coming to forums looking for "Free" help that you are just going to charge for. You should also know better and that reving any engine no load up to 4k is no good for it. What are you going to say to these customers when you deliver an engine back that now has a spun bearing, some piston slap to it, or it decided to throw a rod? Doing that on the garden hose is only worse.... as others have said, there simply isn't enough cooling water. How hot do you think the insides of those risers get?

This is all boat mechanic 101 type stuff. Please take this constructively.... There is no reason to reving an engine up that high with no load... even if there was enough cooling water. You are damaging your customers engines.

 

[oldjeep]

Out of curiosity, what position is the drive in when you are bumping to 4000(ish)rpm