1998 200 hp EFI Mariner Stall

[Bayou_Boy]

First I have researched and read all threads related to outboard stalling. I just bought a used 1998 200 hp EFI Mariner to replace the exact same one that was on my 21 foot Robalo. The old motor dropped a cylinder due to water in the fuel. Before I had the new (used) replacement put on I cleaned the fuel tank completely out. (pain) Then replaced all the fuel lines and blew out the vent to be sure it was not blocked. After getting the new (used) motor put on minus the oil injection the first day ran great. Second day and everyday after it would periodically stall at 2.5K-5K RPMs. I took it back to the (mechanic ? ) and he changed the fuel pump out and replaced the priming bulb and said it was fixed? NOT, still doing it. Yes I ran a separate tank same thing. It will start and Idle great. Some times it will kill during stalls too. Below is a picture I think could be the problem and thinking of changing it but not sure what it is called. Also I have a link to my youtube video so anyone willing to take a guess can see what it is doing. Thanks in advance for any help or thoughts.

Copy & Paste: 200 hp Mariner (1998) Outboard Stall-out - YouTube

 

[wired247]

Re: 1998 200 hp EFI Mariner Stall

That is the vapor separator. Its just a box really. The injection fuel pump is inside there. There is a schraeder valve next to the pressure regulator on the side of that assy where you can check the fuel pressure. Did your mechanic change the mechanical fuel pump or the injection pump?

 

[Bayou_Boy]

Re: 1998 200 hp EFI Mariner Stall

That is the vapor separator. Its just a box really. The injection fuel pump is inside there. There is a schraeder valve next to the pressure regulator on the side of that assy where you can check the fuel pressure. Did your mechanic change the mechanical fuel pump or the injection pump?

He changed the mechanical fuel pump only.

 

[Bayou_Boy]

Re: 1998 200 hp EFI Mariner Stall

He changed the mechanical fuel pump only.

I have another motor exactly the same and thinking about changing the Vapor Separator. What you think?

 

[wired247]

Re: 1998 200 hp EFI Mariner Stall

You can do that but that may not be the problem. First I'd check the fuel pump pressure and if its OK you arent gaining anything by changing it. All you need is a high range tire guage. Those are set for 36 to 39 psi . The fuel pump drivers can go bad though in the ECU. I'd send the ECU in to Brucato or Simon and have it bench tested. Then I'd have the injectors cleaned ( $12 a piece) . Then if it wasnt the pump and was the ECU relay I'd do what a lot of people do who screw with those things and bypass the ECU relay, sh!tcan the stock vapor separator and fuel pump and install a external fuel pump and return regulator like the 260's use and run a return line back to the tank like Mercury should have done in the first place.

 

[Bayou_Boy]

Re: 1998 200 hp EFI Mariner Stall

Thanks I am out of town now and when I get back this weekend I will swap out the ECU first to see if that will correct the issue and let you know how it went.

 

[Bayou_Boy]

Re: 1998 200 hp EFI Mariner Stall

OK, here is an update. When I got back home I swapped out the ECU and took the boat out, still doing the same thing. Worked on it all week scratching my head. Stopped by a marine shop with boat in water running and the mechanic said that it seemed to be running hot on one side. Took the thermostats out and ran boat all day with no problems. The alarm sensor has been removed and it was running hot and shutting down to keep it from over heating. Hopefully that will be all. Guess I should put the alarm back on from other motor. Thanks for the help.

 

[1nebel0]

Re: 1998 200 hp EFI Mariner Stall

You better put new therms back in or you will be buying a new motor due to cold seizing the motor....I got one in the garage now ....Even my Bridgeport racing motors run a washer to help keep some heat in the motor when cold....look it up on the internet for further explanations...

 

[Dukedog]

Re: 1998 200 hp EFI Mariner Stall

Took the thermostats out and ran boat all day with no problems. The alarm sensor has been removed and it was running hot and shutting down to keep it from over heating. Hopefully that will be all. Guess I should put the alarm back on from other motor. Thanks for the help.

Keep looking. There is nothing that will shut that motor down for protection for ANY reason. It will self destruct first. If it won't run right with stats its still broke....Sounds fuel related but not limited to just that. Hard ta tell on a computer

 

[quicktach]

Re: 1998 200 hp EFI Mariner Stall

You initially said "minus the injection" ...are you running premix ? The t-sats should be put back in. Is the motor running hot because it's not getting enough oil or enough of the correct oil ?

 

[reliablemarine]

Re: 1998 200 hp EFI Mariner Stall

sounds like your in need of fuel pump inside vst. you can look up part number on **********. go to ebay there is efi pump like the one you need for 180 dollars

 

[jerryjerry05]

Re: 1998 200 hp EFI Mariner Stall

What's the pressure on the fuel pump(schrader valve)?
I had a 98/225 kept running like crap and would basically do the same thing.
I tested the pressure.It was off by a couple of pounds.
I started asking the local Mercury experts and they said that isin't your problem.
So I checked everything else and 350$ at the dealer he says.
I don't know.The Mercury EXPERT even looked at it and couldn't figure it out.
I changed the regulator and the problem went away.

 

[Bayou_Boy]

Re: 1998 200 hp EFI Mariner Stall

Thank you so much for all the replies. I will put some new stats in before running again. I also have been checking the electronic fuel pump in the VST, I can't remember exactly but I think the pressure was around 32 on the shrader and it was turning on and priming up, I also put a glass filter on fuel line to see if it was pumping when running and it was. I put pic of stats and you can see that one was bad. Also I am not sure (jerryjerry05) what regulator you are implying? (Fuel or Electric)
I still plan on replacing the VST because like you guys say it could be going in and out. Also yes it is pre mix fuel with 50/1 and I always add a touch more. Please keep the suggestions coming. They are very helpful and thanks again.