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Surging at low speed

J

jimp218

New member
"Hello,

I'm having an

"Hello,

I'm having an issue at low speeds (5 miles/hr)- no wake. The engine gains rpms and then slows down like every 5-6 seconds so the boat lunged forward and then slows down. It doesn't happen when going faster then 7- 10 miles/hr, it also doesn't happen when in nuetral or idling. Any ideas.

Thanks,
Jim"
 
"What engine, boat, year, etc?

"What engine, boat, year, etc? Carbed? MPI? What?
Sounds like trouble in the low speed circuit. Float level wrong, flooding, etc.

Rod"
 
"Rod,

Thanks, I bought it

"Rod,

Thanks, I bought it late last year it's a 1987 Four Winns, Mercruiser 165hp, 4cyl (3.7) carbed. It was working fine last year but first time out is when problem started. I was going to tune it up, spark plugs, wires, cap,... Can I get the part from a Auto Parts store if so do you know the coparison make and model?

Thanks,
Jim"
 
"It was also taking on water t

"It was also taking on water through the heat exchanger leaking. But I corrected the problem no more water coming in but it's still surging.

Thanks,
Jim"
 
"Change fuel filter, then Take

"Change fuel filter, then Take off carb and perform a rebuild. I usually disassemble carb and soak in B-12 chem tool, and use shop air to
dry and blow out all internal passages. Be sure to use manual for float level specs and all should be fine.Also check for a sunk float.
as rod stated it sound like debri is fouling up the low speed circuits within carb. Surging
tells me that the debri is moving around within said cicuit, or are just causing lean surge.
kurt"
 
Also consider fuel being old a

Also consider fuel being old and needing replacing. a can of seafoam is also in order.
 
"Kurt,
Thanks for your help,

"Kurt,
Thanks for your help, would you be able to tell me what car engine the 1987 Mercruiser 165hp 3.7 4cyl cross references over when buying at an auto parts dealer for the fuel filter, spark plugs, .....

Thanks,
Jim"
 
There was a big debate on the

There was a big debate on the forum a while ago about whether the 3.7 was used in any vehicle or not. I don't remember the concensus.

At any rate you should probably stick to marine parts. Most on this site would probably suggest the same.

Rod
 
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