fuel pump

[hwy39]

1995 Mercruiser 4.3lx I have had to replace the fuel pump 3 times over the last two years. One time a bad load of gas(full of water) stopped the pump. Both other times the pump worked intermittingly-not good in the ocean. Is this a weak link in the system?

 

[The Marine Doctor]

Re: fuel pump

Is it an electric fuel pump?<br /><br />IF so<br /><br />2 things<br /><br /> <br /><br />I am not sure what year the conversion took place but.<br /><br />For the first years the electric fuel pump got its power from the alternator. You might want to get the alternator checked for output.<br /><br />After this Mercury opted to run the fuel pump with the oil sending unit in line. IF there was and oil problem the pump would quit.<br /><br />2 places to look <br /><br />TMD

 

[hwy39]

Re: fuel pump

Yes the pump is electric. When I take the pump off and hook it directly to a battery, after about 10 minutes of teasing it I can get it to run. It will then work for about two weeks and then freeze again. Same situation on my previous pump. This is why I am curious to see if the fuel pump freezing up is a common problem.<br /><br />Thanks for your previous reply. This pump is in line with the oil pump. No problem with oil system.<br /><br />Thanks,<br /><br />Ken

 

[karayj]

Re: fuel pump

I got a mechnical fuel pump from 89 4.3 merc you can have for 15.00 that includes shipping its worth a shot it will fit jayvete@yahoo.com

 

[Bud Man]

Re: fuel pump

Do you have an in-line water separator before the fuel pump?

 

[boat doc]

Re: fuel pump

welcome to the electric fuel pump world and boats.....lol. How often do you run your boat, or change your fuel. Usually what I see are people that run there boat 2 to 3 times a year and fill up maybe 2 times, meaning bad gas. Fuel has a shelf life of like 10 days. What I am getting at is old fuel leaves deposits in your fuel system, these deposits are usually dry and flakey when there is not any fuel present, add fuel, and the deposits get gummy, causing fuel system nightmares, ie fuel pumps, carbs, injectors sticking. Does the fuel pump get so hot that you cannot touch it? I have this problem with brand new boats still in the shrink wrap. merc was the worst, i don't know, mybe the pump they use.<br /><br />One cure that I like is using a fuel shut off at the fuel tank outlet, and run your fuel system dry when you are finished with your boat. Always use fuel stabilizer when you are not going to use your boat for a few weeks

 

[hwy39]

Re: fuel pump

Yes, there is an in line fuel filter(water separator) before the fuel pump. I use the boat weekly for wake boarding in the harbor. Tank is full of fresh fuel weekly. <br /><br />I guess the good news is that not many owners are experiencing premature fuel pump failure. The fuel pump I am currently using I teased back to life and hope it will continue.<br /><br />Thank you for all of the responses. <br /><br />Ken

 

[Bopper1]

Re: fuel pump

I have a 93 4.3L LX and have the same trouble. Yesterday I checked the voltage at the pump (part # 861155A 6) and had voltage there while cranking and also after stopping cranking but leaving the key on until the oil pressure got down to zero.The pump never ran and therefore the engine would not start once the fuel in the carb from advancing the throttle a couple of times was gone. I cranked maybe 10 times and then finally upon stopping cranking but not turning the key off I heard the pump running. Next time I cranked it over it started right up. Runs great then. Does this every time the engine is cold. I first listened for the pump last week and it did the same thing so that's why I checked for voltage yesterday. I don't think that fuel would cause that. Once it starts running it is fine. I have never had it quit. I bought the boat a year ago, so I'm not sure if the pump is original or not. Is this an ongoing problem with Mercruiser fuel pumps? Anybody got any good ideas?

 

[MIKE1155]

Re: fuel pump

I have the same problem with the same motor. But I was told to replace the anti syphon valve as it was faulty and allowing the fuel to drain back to the tank. This causes the fuel pump to lose it's prime, after cranking for a while the fuel returns. Does this make sense?

 

[hwy39]

Re: fuel pump

My problem is not the antisiphon valve. My pump justs stops spinning and I have to tease it with direct hook up to the battery to get it spinning again. It will click about 10 time and then finally( if I am lucky) start spinning again and is good for the day.<br /><br />hwy39

 

[dick]

Re: fuel pump

One ting I have to say is running those inline pumps dry(without fuel running through them )is bad.The two main things the kill those pumps are water and running them dry.You may have the voltage problem that The Marine Doctor said.The bad news is if you have been running the pump dry on a bench you may have fried that pump.

 

[Bopper1]

Re: fuel pump

I used my boat 2 days ago and it is still the same senario as I wrote about before. I'm going to try putting an amp meter in line with the pump to see if when it gets voltage there is any amps. This should tell me if there is a bad connection internally in the pump (no amps) or if the pump is sticking (higher than normal amps) and then finally frees up and starts spinning (normal amps). I'm betting on the second one as once it starts running it runs great and only does this when it has sat for a while like overnight.I'm assuming that if it is sticking there is no cure but a new pump. What Boat Doc says about the fuel and gumming up the pump makes sense. Would something like Gumout or Seafoam work to free it up or am I headed down that new high $$ pump road? I also replaced the anti-syphon valve about a month ago. It was bad and so there was no fuel in the line. Maybe this was a contributing factor to this whole mess.