losing power ( mid to hi rpm) on my '88 350 Mag/Alpha. runs great at low rpm but when i give her the throttle, she planes out and then arbitrarily loses rpms and slows (does not stall) already replaced f/w separator ( clean), in line carb filter, dist cap. rotor , plugs, wires. next on my hit list is a anti-siphon valve and a fuel pump. recently tighented loose power steering and alternator belts. any other suggestions?
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'88 350 Mag?ALpha Mid to Hi RPM losing power - Fuel related??
- Thread starter mh
- Start date
happy
Active member
I wouldn't just throw parts at it to see if the problem goes away. Solid diagnositcs is the way to go.
Compression check and spark plug evaluation,
Exhaust manifold condition,
Any water in the oil?
Fuel tank vent, fuel lines, ect.
Battery cables, and all engine grounds.
Carburator??? ..
Overheating?
This is a simple set up, yet many things can cause this issuer
Compression check and spark plug evaluation,
Exhaust manifold condition,
Any water in the oil?
Fuel tank vent, fuel lines, ect.
Battery cables, and all engine grounds.
Carburator??? ..
Overheating?
This is a simple set up, yet many things can cause this issuer
thanks happy, well i should have taken your advice but i purchased and replaced the fuel pump and now she runs worse than ever. got her up in plane and started doing the same thing- engine losing rpm, now i have with difficulty with idling ( will not idle and running very rough) along with the losing power issue at higher rpm. i pulled a few plugs (look ok) . coil looks ok ( no carbon deposits or cracks); checked all electrical connections. would the ignition sensor in the distrbutor cause this isuue as i am at a loss here.
snowmank570
New member
Have you tried taking the fuel pick up tube out of the tank and cleaning the screen. I just had mine apart over the weekend. The screen was inside the pickup tube and it was half plugged. My boat ran just like yours did. I couldnt go over 4000 rpms. Now i am back up to 4800 if i want it. I also got rid of the checkvalve that was in the elbo on the pickup tube and put a elbo that was straight through. runs great now. 
raceinsnow
New member
Another thing to check is the float in the carb.I just had this problem on a 4.3.The float was gas soaked and the motor would run great until the 4 barrel would kick in.I would also check the fuel pick up tube for cracks and debris,also when you have the inspection cover off the tank look for crap in the tank floating around.
Don's89 Senator
Well-known member
GO CHECKMATE!!!!
raceinsnow
New member
If the float was full of fuel it would run like crap going slow and run better wide open.
You are right Big Red I forgot to add that someone was there before me and adjusted the float level so it would run at an idle.I ended up replacing the float and cleaned and rebuilt the carb and that motor ran alot better.Sorry about the confusion.
You are right Big Red I forgot to add that someone was there before me and adjusted the float level so it would run at an idle.I ended up replacing the float and cleaned and rebuilt the carb and that motor ran alot better.Sorry about the confusion.