fuel starved merc. 5.7

[Derk138]

I have a 1990 merc. 5.7 w/a 4 barrel carb.<br />The problem is when I power up and the 4 barrel kicks in, the engine wants to stall out but doesn't. The motor runs fine up to about 3500 rpms and ideals just great. It back fired once while trying to power up. I replace the fuel/water seperator. The boat wouldn't start at first but we figurged out the fuel/water filter was on to tight. When loosen the engine fired right up. Could this filter be a problem, its a seria filter not a merc.First time and had to use since that was all the had left at the store. Can some one point me in the right direction so i don't replace everything ($$$$$) before I find the real problem. <br />Thanks for any help.

 

[magster65]

Re: fuel starved merc. 5.7

The filter on too tight? I don't get it. It sounds to me, assuming you have a Rochester carb., like the small filter in the carb. itself is obstructed.

 

[akriverrat]

Re: fuel starved merc. 5.7

is spin on filter gasket same diameter as old one?

 

[Derk138]

Re: fuel starved merc. 5.7

I assume it is the same size gasket, but can't be sure. I'm going to replace the filters, if it stops raining. <br />Thanks for spending your time to respond and I'll let you know how it works out.

 

[2770]

Re: fuel starved merc. 5.7

Make sure they did not sell you an oil filter in stead of fuel/water.Check and replace the small filter at the carb.Get a good marine water absorber for the fuel and check for proper choke operation and also if it acts up after a rain,remove dist. cap and look for condensation inside cap.I had a boat that did the same. CC

 

[Derk138]

Re: fuel starved merc. 5.7

I replaced all the fuel filters. Same problem but it will run a few hundred yards before it boggs down. So that is an improvement. I added dry gas to 40gals of fuel also last week. I'll check the distriburer. It has been raining and cool weather here.

 

[Derk138]

Re: fuel starved merc. 5.7

this might sound strange but I added a new SS prop. 19" that was the only modification that I did. Same pitch and size but changed form alum to SS. Could this cause to much stress on the engine now that I'm getting less slip in the water. I wouldn't think so but who knows.

 

[2770]

Re: fuel starved merc. 5.7

Dont use dry gas.Get a water absorber from a marine store.Dry gas is for a few drops of water in gas.Boats accumulate a lot more than that.Dont be shy to spend 10 bucks on a quality product,it may make the difference.I have been towed in for water in the gas.The tow was a lot more than 10 bucks. CC

 

[akriverrat]

Re: fuel starved merc. 5.7

a restriction in fuel system befor water seperator will allow enough gas through for low speed operation and let you get short runs of high speed befor available reserves in filter/line/carb are used up. just been through this on my starboard tank.

 

[Yepblaze]

Re: fuel starved merc. 5.7

A kinked steel fuel line near the carb can be a common problem. If it looks like it has been twisted replace it with a new part.

 

[Derk138]

Re: fuel starved merc. 5.7

For those who were interested, the salution was found. It was the carburator, the floats were all gumed up and it just need a good cleaning. After 10 years of use it was due and only cost me $50. (Thats about $5 in the boating world). The boat runs like a dream and thanks for all your advice.