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Intermittent surging in 454 crusader

K

ken_o

New member
"In my 1985 Trojan - I am gett

"In my 1985 Trojan - I am getting an intermittent surging in the port engine. This happens after I go up on plane (running well), back down @ a no wake and then attempt to go back up again. If I set the rpm's approximately @ 3K for the starboard engine, and attempt to do the same w/ the port engine, it will not go above 2600 then after ~ 30 seconds will shoot up to 3K. As an FYI - this engine has a new long block in 07, w/ a new head as well (went bad in 08 - rpms would not go above 2K - mechanic found cracks that allowed water in ). I've changed the filters and keep fresh gas and C Foam additive to keep the fuel from separating. Additionally, after the engine starts surging, I pull into a cove where you can beach, and this same engine will not go above 1500 rpm when under a serious load (going up on the sand). Has anyone experienced anything like this?"
 
"You need to look at the plugs

"You need to look at the plugs and see what color they are running. That will eliminate bad ignition if they are all nice and light tan. If they are stark white, start looking for gas starvation: dirt in carbs, dirty filters, fine filters placed BEFORE a fuel pump, etc.

These things don't solve themselves. You have to do some detective work to narrow down the possibilities.

Jeff"
 
"jeff - thanks, I'll check

"jeff - thanks, I'll check the plugs and post it tomorrow. Any speculation as to why it's present and then disappears? case in point, the previous weekend it was present, then I took the boat on a 80 mi r/t cruise and did not experience it all."
 
"85? I'd check the fuel li

"85? I'd check the fuel lines for cracks, loose clamps, deteriorated fittings. Also, check the pickup tubes (clogged screens) and malfunctioning anti-syphon valve.

Is the new stuff the old style MarkIV or did they go with a GenV/VI?"
 
"Makomark, I'm assuming I

"Makomark, I'm assuming I'd need to remove the p/u tube from the tank to check, what about the anti siphon valve - where is that located and how do you check it? What about the O ring @ the fuel fill? If that is deteriorated, could that be a factor?"
 
"The oring at the fill plate k

"The oring at the fill plate keeps water and other crud from draining into the tank(s). Its inspection is on my winterize list, every year.

You'll have to unthread the pick up tubes to inspect them. The antisyphon valves are usually incorporated into the fitting on the outlet of the pickup tube.

Do you have a common tank or individual ones? Any cross-over valves? They get an annual inspection, too. (make sure they are fully opened, too.)"
 
MM- I'll check the o ring

MM- I'll check the o ring as well - the p/u tubes I imagine would be removed from the top of the tank (single tank) no crossover valves - it feeds both engines and the gen set
 
"not sure will need to trace i

"not sure will need to trace it - btw - genset not running, so have the valve to it turned off"
 
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