2001 5.0L EFI - start-surge-die problem

[Barefootr]

Looking for a little help - hopefully one of you experienced guys know what's happening with my Merc.

I have a 2001 Merc 5.0L EFI that suddenly doesn't want to stay running. It started and ran fine out to a nice cove where I anchored off and enjoyed some swim time with friends. When I tried to restart the engine to head back it started after a few seconds, ran up to about 1300 RPM (idle is normally around 800 RPM) and then died. I waited a minute and tried again with the same results. After several repeats with the same result I gave up and took a tow back to the dock.

Does this sound familiar to anyone? I'm thinking maybe a fuel flow problem, but not sure how that would come on so suddenly. Sensor failure? Hopefully not the $1900 ECM. Looking for some good advice on where to start checking. Have lot's of experience with automotive engines and understand tech talk. Looking forward to hearing from a more experienced boat mechanic.

 

[Reel Poor]

Re: 2001 5.0L EFI - start-surge-die problem

Have you done a full tune up on it? Have you checked or changed the fuel filter? The fuel filter would be my first stop.

 

[flabum]

Re: 2001 5.0L EFI - start-surge-die problem

First check the fuel water seperator for water. Refill with fuel and re-install or replace. Always fill the fuel water seperator with fuel before installing it, this keeps from burning up the fuel pump by it running dry. Next, check the fuel pressure. Fuel pumps are a common failure on those. Assuming that is an MPI (Not a TBI), the pressure should be 43 PSI. Fuel pressure loss can be caused by delivery problems such as restrictions or leaks, bad fuel pump or a bad fuel regulator. A common problem on those can also be a clogged regulator screen that will give you a high pressure reading, but this usually won't cause a stall, just makes it run rich.

This problem sounds to me to be fuel related and not electrical or computer related. Your description of it revving then dying indicates a fuel starvation.

 

[Barefootr]

Re: 2001 5.0L EFI - start-surge-die problem

Thanks for the help. Here's my result so far-

Replaced fuel filter and seemed to be OK. Ran for 25 minutes on trailer with muffs so I took it out on the water for a shakedown. No problems starting/restarting during 45 minutes of testing after various speed runs, idling, etc. Then I shut off the engine for about 20 minutes and my problems began again when I attempted to restart it. The engine started and then surged up and down twice before dying. Second try was similar, but it actually ran normal for a few seconds before dying again. Now it won't start.

Seems like maybe an intermittent sensor failure to me. Will have to check out the electrical side next. Let me know if you have any specific suggestions. I may have to give it to the shop soon - family is (understandably) getting impatient.

FYI - it's a TBI (not MPI) fuel injection system.

 

[Don S]

Re: 2001 5.0L EFI - start-surge-die problem

Did you inspect your filters the first time you changed them to see if there was any water in them? It's very possible that you have a lot of water in your tank, and while sitting bow down on the trailer you actully get good gas to the engine and everything works. THen when you put it in the water and the bow is high you pick up water again till the filter is full then you have water in the EFI again.
Check the filters that are now on the boat and see if there is water in them.

 

[Bondo]

Re: 2001 5.0L EFI - start-surge-die problem

Looking forward to hearing from a more experienced boat mechanic.

Ayuh,.... Welcome Aboard,....

You're talking to a couple of the Best here at iboats,......

RP,+ Flabum like these newfangled Electronic stuff,.....
I'm still doin' Carbs...

If you look Here,.... You should be able to find a copy of the Mercruiser Factory Manual for your motor,+ drive....

 

[Barefootr]

Re: 2001 5.0L EFI - start-surge-die problem

Don S. -

I inspected the old filter, but not for water content specifically. What's the best way to evaluate the current filter for water content?

Bond-o - thanks for the service manual link.

Thx,
Barefootr

 

[Don S]

Re: 2001 5.0L EFI - start-surge-die problem

Dump the contents into a clear container. The water will seperate and be on the bottom. I have also found filters that were about 99% water, so be sure of what you are seeing.

 

[JustJason]

Re: 2001 5.0L EFI - start-surge-die problem

high idle speed on an efi (basic throttle body) is usually unmetered air entering the engine..... spray some soapy water or a foaming 6 in 1 oil around the tbi base gasket, the throttle shaft area, and all over the intake edges and see if its getting sucked it.

 

[newport dave]

Re: 2001 5.0L EFI - start-surge-die problem

high idle speed on an efi (basic throttle body) is usually unmetered air entering the engine..... spray some soapy water or a foaming 6 in 1 oil around the tbi base gasket, the throttle shaft area, and all over the intake edges and see if its getting sucked it.

What does this have to do with the posters issue?

When beginning to stall, a computer controlled engine will advance the timing and IAC position in an attempt to stay running, resulting in a surge before the engine dies. This does not mean you have a vacuum leak. It usually means the fuel supply has been cut off for whatever reason. Check the fuel pressure.

 

[JustJason]

Re: 2001 5.0L EFI - start-surge-die problem

I was under the assumption this was a TBI motor.... is it not?

 

[shdw2001h]

Re: 2001 5.0L EFI - start-surge-die problem

I had the same problem with my volvo penta. it ened up being a bad battery, it would not hold up under load and would let the it run at idle, if I gave it any gas it would run for a while then start to surge and die, after that it would be hard to start, if it starts. After it sits for a while it would start back up with no problem. you might want to have the battery tested.