Mercury EFI fuel pump

[bobco]

Just learned about a service advisory for Mercury EFI's. There is a vaccum , diaphram , initial fuel pump that has caused trouble. The material that the diaphram was made of deterioated from our modern fuel mixtures. They have a replacement kit to upgrade the fuel pump. Part number 85700a1 for $12 at your local merc parts dealer. I have had some intermittant problem so I'm going to put it in , the service advisory is number 99-5. Once again I have to say how great Mercury customer serivce is , they will talk to the average joe and give out technical information, I still have a bad taste in my mouth from dealing with Honda, not only won't they talk to you they are down right RUDE!

[HarryE]

Bob,

Does this apply to all Merc EFI's? I did notice my 175 "stalled" at almost WOT once or twice last year but then it never did it again. Does this sound like the reason for the service advisory?

[bobco]

They said 87 and up on the EFI models with a square fuel pump. The problem is getting fuel to the electric fuel pump so any lose of fuel problems could be related....the mercury rep said that they can do a vaccum check to see if you have a problem, since it is only $12 for the kit and there is a known problem with the diaphram material I plan to change it if nothing more than preventive maintence....hope this helps.

[todd176]

I have also heard of people talking about this problem on some other sites and this is the first time I have heard about the advisory by Mercury. The problems that I have heard about are that the motor will quit at WOT and also if it idles for to long. I had my 175 EFI last year quit on me if I would idle it to long, but never thought much about it till know. Has any one tried to replace this diaphram them self's or do you need to take it in for service? What kind of manual would you suggest? does Mercury have any info on there web site about the sevice advisory? any info would be great...Thanks...

[bobco]

I'm going to get the kit and do it myself. Doesn't sound like any big deal, may have to drill out to 1/8" a couple of holes for mounting screws. I'm doing to ask to look at the service adviory 99-5 when I go into get the kit, to see if there is any special instructions. For $12 for the kit is good preventive mantiance in my book. I do have a 175 EFI service manual I will look to see what is involved.

[HarryE]

Bob and Todd,

I appreciate the advice and it might be a good idea that we all keep in touch since we all have 175 Merc EFI's. My e-mail address is southwest4@aol.com

Thanks guys,

Harry

[Cory]

Hey guys, me too. I have a new 175 EFI and 2-3 times last year it shut right off. I do not know if I was WOT but probably 2/3 to 3/4 throttle. I am going to contact my dealer and ask his opinion.

[HarryE]

I called my local Mercury dealer today and they told me that this service advisory was for motors made in the mid to late 80's to early 90's. My EFI 175 is a 1999 and was told this shouldn't be a problem with the newer motors. Now wondering what made mine cough twice like that back in the fall of '00. Maybe just a molecule of moisture somewhere.

[bobco]

Mercury customer service rep said it was effecting 1987 and up motors with the square fuel pump, I looked at my serivce manual and it looks like a realitivly easy job to change out the diaphram and check valves, like I said earlier this is not a fix all and your dealer can check the vaccum your pump is pulling to see if you are having this problem, I figure it will cost me allot more to pay an .5 hr service to check it out than the $12 for the kit, I read somewhere that is a good idea to change the pump every coouple years anyway....